Burner control units BCU 480

Technical Information · GB
6 Edition 11.19

• For pilot and main burners in intermittent or continuous operation

• Flame control by UV, ionization or a further option of using the
furnace chamber temperature
• Simple system integration using the PC programming and
diagnostic software BCSoft
• With optional valve proving system
• Fieldbus connection (PROFIBUS, PROFINET, EtherNet/IP) using
optional bus module


Contents
Burner control units BCU 480 . . . . . . . . . . . . . . . . . . . . . . . . 1 5.1.2 Program sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.1.3 Test period tP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
5.1.4 Opening time tL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1.5 Measurement time tM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.1 Application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2 Proof of closure function . . . . . . . . . . . . . . . . . . . . . . . . . 39
1.1.1 Stage-controlled main burner with alternating 5.2.1 Program sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
pilot burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1.2 Stage-controlled main burner with permanent
6 BCSoft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
pilot burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7 Fieldbus communication . . . . . . . . . . . . . . . . . . . . . . . . . 41
1.1.3 Two-stage-controlled main burner with 7.1 BCU and bus module BCM . . . . . . . . . . . . . . . . . . . . . . . 42
permanent pilot burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.2 Configuration, planning . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.1.4 Staged control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.2.1 Device master data file (GSD), electronic data
1.1.5 Modulating control with defined ignition position . . 11 sheet (EDS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.1.6 Flame control using the temperature . . . . . . . . . . . . . . . . 12
1.1.7 ON/OFF rotary impulse control . . . . . . . . . . . . . . . . . . . . . . 13 7.3 PROFINET, EtherNet/IP . . . . . . . . . . . . . . . . . . . . . . . . . . 44
1.1.8 Modulating burner control . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7.3.1 Modules for process data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
1.1.9 PROFINET connection using bus module BCM . . . . . 16 7.3.2 Device parameters and statistics . . . . . . . . . . . . . . . . . . . . 49
2 Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7.4 PROFIBUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8 Program step/status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1 Part designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 9 Fault signalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.2 Connection diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 10 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.2.1 BCU 480..E1/LM 400..F3..E1 10.1 Application parameters . . . . . . . . . . . . . . . . . . . . . . . . . 56
with ionization control in double-electrode operation . . . . 19 10.2 Interface parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
3.2.2 BCU 480..P3..E1/LM 400..F3..E1
with industrial plug for ionization control in double-
10.3 Scanning the parameters . . . . . . . . . . . . . . . . . . . . . . . 63
electrode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 10.4 Flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3.2.3 Flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 10.4.1 Burner 1 flame signal FS1 switch-off threshold . . . 63
3.2.4 Assignment of connection terminals . . . . . . . . . . . . . . . . 23 10.4.2 Burner 2 flame signal FS2 switch-off threshold . . . 64
10.4.3 Flame simulation check in standby position . . . . . . . 65
3.3 BCU 480 program sequence . . . . . . . . . . . . . . . . . . . . . 25
10.4.4 High temperature operation . . . . . . . . . . . . . . . . . . . . . . . . 67
4 Air control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 10.5 Behaviour during start-up . . . . . . . . . . . . . . . . . . . . . . 70
4.1 Capacity control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 10.5.1 Burner 1 start-up attempts . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.1.1 BCU..F1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 10.5.2 Burner 2 start-up attempts . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.1.2 BCU..F3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 10.5.3 Burner application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5 Valve proving system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 10.5.4 Pilot burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
10.5.5 Safety time 1 tSA1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.1 Tightness control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10.5.6 Flame proving period 1 tFS1 . . . . . . . . . . . . . . . . . . . . . . . . 77
5.1.1 Test instant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
10.5.7 Safety time 2 tSA2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

BCU 480 · Edition 11.19 ▼ = To be continued 2


10.5.8 Flame proving period 2 tFS2 . . . . . . . . . . . . . . . . . . . . . . . . 78 10.14.3 Function of terminal 64 . . . . . . . . . . . . . . . . . . . . . . . . . 102
10.6 Behaviour during operation . . . . . . . . . . . . . . . . . . . . . 79 10.15 Functions of contacts 80 to 97 . . . . . . . . . . . . . . . 103
10.6.1 Restart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 10.15.1 Contact 80, 81/82 function . . . . . . . . . . . . . . . . . . . . 103
10.6.2 Minimum operating time tB . . . . . . . . . . . . . . . . . . . . . . . . 81 10.15.2 Function of contact 90, 91/92 . . . . . . . . . . . . . . . . . 103
10.7 Safety limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 10.15.3 Function of contact 95/96 . . . . . . . . . . . . . . . . . . . . . 103
10.7.1 Safety time during operation . . . . . . . . . . . . . . . . . . . . . . . 82 10.15.4 Function of contact 95/97 . . . . . . . . . . . . . . . . . . . . . . 103
10.15.5 Function of contact 85/86, 87 . . . . . . . . . . . . . . . . . . 103
10.8 Air control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
10.8.1 Running time selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 10.16 Functions of inputs at terminals 1 to 7 and
10.8.2 Running time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 35 to 41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
10.8.3 Over-run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 10.16.1 Function of input 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
10.8.4 Air actuator control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 10.16.2 Function of input 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
10.8.5 Air actuator can be activated externally on start- 10.16.3 Function of input 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 10.16.4 Function of input 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
10.8.6 Air actuator in the event of fault . . . . . . . . . . . . . . . . . . . . 88 10.16.5 Function of input 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
10.8.7 Combustion mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 10.16.6 Function of input 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
10.9 Valve check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 10.16.7 Function of input 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
10.9.1 Valve proving system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 10.16.8 Function of input 35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
10.9.2 Relief valve (VPS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 10.16.9 Function of input 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
10.9.3 Measurement time for Vp1 . . . . . . . . . . . . . . . . . . . . . . . . . 91 10.16.10 Function of input 37 . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
10.9.4 Valve opening time tL1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 10.16.11 Function of input 38 . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
10.16.12 Function of input 39 . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
10.10 Behaviour during start-up . . . . . . . . . . . . . . . . . . . . . 92 10.16.13 Function of input 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
10.10.1 Minimum pause time tMP . . . . . . . . . . . . . . . . . . . . . . . . . 92 10.16.14 Function of input 41 . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
10.11 Manual mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
10.11.1 Operating time in Manual mode . . . . . . . . . . . . . . . . . . 92
11 Replacement possibilities . . . . . . . . . . . . . . . . . . . . . . 107
10.12 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 12 Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
10.12.1 Function of sensor 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 12.1 Burner control unit BCU . . . . . . . . . . . . . . . . . . . . . . . 109
10.12.2 Function of sensor 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 12.1.1 Type code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
10.12.3 Function of sensor 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 12.2 Power module LM 400 . . . . . . . . . . . . . . . . . . . . . . . . 110
10.12.4 Proof of closure function test period . . . . . . . . . . . . . 94 12.2.1 Type code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
10.13 Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 13 Project planning information . . . . . . . . . . . . . . . . . . 111
10.13.1 Fieldbus communication . . . . . . . . . . . . . . . . . . . . . . . . . 95
10.13.2 K-SafetyLink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
13.1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
10.13.3 Safety interlocks (bus) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 13.2 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
10.13.4 Purge (bus) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 13.3 Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . 112
10.13.5 High temperature operation (bus) . . . . . . . . . . . . . . . . 96 13.3.1 Safety current inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
10.13.6 LDS (bus) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 13.4 Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
10.14 Interface parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 97 13.5 Parameter chip card . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
10.14.1 Flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
13.6 K-SafetyLink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
10.14.2 Air actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

BCU 480 · Edition 11.19 ▼ = To be continued 3


13.7 Overload protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 19.4 SIL and PL for BCU 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
13.8 Calculating the safety time tSA . . . . . . . . . . . . . . . . . . . . . . 115 20 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
14 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 21 Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
14.1 High-voltage cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 22 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
14.2 Industrial plug connector, 16-pin . . . . . . . . . . . . . . 116 22.1 Waiting time tW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
14.3 BCSoft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 22.2 Safety time on start-up tSA1 . . . . . . . . . . . . . . . . . . 130
14.3.1 Opto-adapter PCO 200 . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
22.3 Safety time on start-up tSA2 . . . . . . . . . . . . . . . . . . 130
14.4 Connection plug set . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
22.4 Ignition time t Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
14.5 Set of language stickers . . . . . . . . . . . . . . . . . . . . . . . . 117
22.5 Safety time during operation tSB . . . . . . . . . . . . . . . . . . . 130
14.6 Fastening set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
22.6 Safety interlocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
14.7 External securing bars . . . . . . . . . . . . . . . . . . . . . . . . . 117
22.7 Safety shut-down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
14.8 Bus module BCM 400 . . . . . . . . . . . . . . . . . . . . . . . . . 117
22.8 Safety shut-down with subsequent lock-out
14.9 Flange plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 (fault lock-out) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
15 BCM 400 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 22.9 Warning signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
15.1 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 22.10 Timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
15.2 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 22.11 Air actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
15.3 Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . 119 22.12 Safe failure fraction SFF . . . . . . . . . . . . . . . . . . . . . . 132
15.4 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 22.13 Diagnostic coverage DC . . . . . . . . . . . . . . . . . . . . . . 132
15.5 Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 22.14 Mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
15.6 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 22.15 Probability of dangerous failure PFHD . . . . . . . 133
16 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 22.16 Mean time to dangerous failure MTTFd . . . . . 133
16.1 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
16.2 Mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
16.3 Ambient conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
16.4 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
17 Converting units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
18 Safety-specific characteristic values for SIL
and PL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
19 Safety information in accordance with
EN 61508-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
19.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
19.2 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
19.3 Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

BCU 480 · Edition 11.19 ▼ = To be continued 4

Application

1 Application in the immediate vicinity of the burner being monitored

simplifies system integration.
On industrial furnaces, it reduces the load on the cen-
tral furnace control by taking over tasks that relate to
the burner, for example it ensures that the burner ig-
nites in a safe condition when it is restarted.
The air control on the BCU..F1 or F3 assists the furnace
control for cooling, purging and capacity control tasks.
The burner control unit has an interface via which an air
valve or actuator can be controlled for staged or modu-
lating burner capacity control.
The program status, device parameters, error codes,
statistics and level of the flame signal can be read eas-
ily and conveniently on the four-digit device display.
The burner can be controlled manually for commission-
ing, maintenance and diagnostic purposes.
The next-generation burner control unit BCU 480
unites the components of automatic burner control Energy management using phase reduces the instal-
unit, ignition transformer, Manual/Automatic mode, lation and cabling costs. The valves and ignition trans-
display of operating and fault statuses and a user inter- former are powered by phase L1/the voltage supply for
face (HMI) in a compact metal housing. It replaces the the BCU instead of the safety interlocks.
previous product line with the same name. It is suitable The monitored outputs for the actuator and valve are
for almost every conceivable multiple burner applica- housed in the plug-in power module LM 400. This can
tion in the metal, ceramics, food and automotive indus- easily be replaced if necessary.
tries.
It can be used for gas burners of unlimited capacity
which are ignited by pilot burners. The burners may be
modulating-controlled or stage-controlled. Installation

BCU 480 · Edition 11.19 5

Application
or EtherNet/IP) using the BCM. Networking in a field-
bus system enables the burner control unit BCU to be
controlled and monitored by an automation system
(e.g. PLC). This also opens up a wide range of process
visualization possibilities.

Power module LM 400 with connections for valves, actuator

and parameterizable signalling contacts
Thanks to the optionally integrated valve proving sys-
tem, the valves can be checked for leaks by querying
an external gas pressure switch or it can be checked
whether gas valves are closed. Bus module BCM 400 for internal connection to the BCU
As an option, the BCU can be configured with high tem-
perature operation. In High temperature mode, the BCU
can monitor the flame indirectly using the temperature.
Using the BCSoft program, the parameters, analysis
and diagnostic information can be read from a BCU via
the optionally available opto-adapter. If necessary, the
device parameters can be adjusted easily using BCSoft.
All valid parameters are saved on an integrated param-
eter chip card. The parameter chip card can be removed
from the old unit and inserted into a new BCU to trans-
fer the parameters, for example when replacing the unit.
The burner control unit is IIoT-compatible using the bus
module BCM 400. The BCU can be networked with a
standardized fieldbus system (PROFIBUS, PROFINET

BCU 480 · Edition 11.19 6

Application

1.1 Application examples

V1 V2 1.1.1 Stage-controlled main
burner with alternating pilot
VAS VAG
VAS 1 burner
Control:
V4 Main burner ON/OFF or High/Low
Process control (PCC) The main burner can be started with
FCU 500 PLC reduced capacity after the operat-
ing signal from the pilot burner has
been detected. The pilot burner is
switched off automatically after the
1 2 ϑ1 A ϑ2 main burner has started up. When
1 4 2
the main burner is switched off, the
95 96 95 97 5
41 pilot burner automatically switches
BCU 480/LM..F3
35 42 1 on again. This reduces the main

S
UV
µC 43 2
HT 6 60 burner start-up time.
61
P 3 63 The UV sensor monitors the flame
65 23 signal from pilot and main burners.
VR..L
The BCU provides the cooling and
purging processes.

02–04 06–08 02–04 06–08

ϑ1
1
ϑ2
2

BCU 480 · Edition 11.19 7

Application
1.1.2 Stage-controlled main
burner with permanent pilot
burner
V1 V2
Control:
Main burner ON/OFF or High/Low
VAS VAG
VAS 1
The main burner can be started with
V4 reduced capacity after the operat-
ing signal from the pilot burner has
Process control (PCC)
FCU 500 PLC been detected. Pilot and main burn-
ers can be operated simultaneously.
This reduces the time required by
the main burner for starting up.
The BCU provides the cooling and
1 2 ϑ1 A ϑ2
purging processes.
1 4 2
95 96 95 97 5
BCU 480/LM..F3 41

35 42 1

µC 43 2
HT 6 60
61
P 3 63

65 23

VR..L

02–04 06–08 04 06–08 04

ϑ1
1
ϑ2
2

BCU 480 · Edition 11.19 8

Application
1.1.3 Two-stage-controlled main
V3 burner with permanent pilot burner
Control:
V1
V2 Main burner ON/OFF with ignition
via bypass
VAS VAG
VAS 1 The main burner can be started
with minimum capacity after the
V4
operating signal from the pilot
Process control (PCC)
burner has been detected. When
FCU 500 PLC
the operating state is reached, the
BCU issues the enable signal for
the maximum burner capacity. Pilot
and main burners can be operated
1 2 ϑ1 A ϑ2 simultaneously. This reduces the
95 96 95 97
1 4 2 time required by the main burner for
5
BCU 480/LM..F1 starting up.
60
35 61
62 The BCU provides the cooling and
µC
HT 6 63
purging processes.
P 3 23

66 65 40 41

10 16
4 µC
14
7 M 12

02–04 06–08 04 06–08 04 IC 40 + BVA

ϑ1
1
ϑ2
2

BCU 480 · Edition 11.19 9

Application
1.1.4 Staged control BCU and the butterfly valve BVA is set to the pre-purge
position.
Process control (PCC)
FCU 500 PLC
In the event of a temperature demand, the burner con-
trol unit BCU activates input DI 1 via the output at ter-
minal 65 and moves the butterfly valve to the ignition
position (condition: the IC 40 must have reached the
P HT Start 1 A Start 2
ignition position on the instant of ignition). The burner
3 6 35 1 2 4 5
starts.
81
BCU 480..F1 82
µC The burner application “Burner 1 with pilot gas” (pa-
95
96
rameter A078 = 1) is selected so that the burner can be
23 started with a limited start fuel flow rate.
60 61 62 63 65 66 40 41
To activate the high-fire rate, DI 2 is actuated via the air
V3
valve output at terminal 66 of the BCU.
V1 The butterfly valve moves cyclically between the high-
V2
fire and low-fire rate position, see page 100 (Operat-
VAS VAG
ing mode 11).
DI 1/ DI 2/ IC 40 position Valve position
Trm. 65 Trm. 66
V4 Off Off closed Closed
Ignition position/Low-fire
S
UV

On Off low rate

14
7 µC
16
On On middle High-fire rate
10
4 M 12
Off On high Pre-purge

IC 40 + BVA

The central control system starts the pre-purge. Input

DI 2 is activated via the output at terminal 66 of the

BCU 480 · Edition 11.19 10

Application
1.1.5 Modulating control with defined ignition In the event of a temperature demand, the burner con-
position trol unit BCU activates input DI 1 via the output at ter-
minal 65 and moves the butterfly valve to the ignition
Process control (PCC)
position (condition: the IC 40 must have reached the
FCU 500 PLC
mA ignition position on the instant of ignition). The burner
starts.
The burner application “Burner 1 with pilot gas” (pa-
P HT Start 1 A Start 2
3 6 35 1 2 4 5
rameter A078 = 1) is selected so that the burner can be
81
started with a limited start fuel flow rate.
BCU 480/LM..F1 82
µC During operation, the BCU activates DI 1 and DI 2 using
95 outputs 65 and 66. This enables the analogue input IN
96

60 61 62 63 65 66 40 41
23 on the actuator IC 40. Depending on the capacity de-
mand of the temperature controller, the butterfly valve
V3
BVA moves steplessly between the low-fire rate and the
high-fire rate to the position specified by the analogue
V1
V2
input IN, see page 100 (Operating mode 27).
DI 1/V1 DI 2/Air valve IC 40 position Valve position
VAS VAG
Off Off closed Closed
Ignition position/Low-
On Off low
V4
fire rate
On On analogue chart 1 In acc. with chart 1
S
UV

Off On high Pre-purge/High-fire rate

14 16
7 µC
10
4 M 12
IN 18

IC 40 + BVA

The central control system starts the pre-purge. Input

DI 2 is activated via the air valve output of the BCU and
the butterfly valve BVA is set to the pre-purge position.

BCU 480 · Edition 11.19 11

Application
1.1.6 Flame control using the temperature ing the flame signal and their internal flame control is
non-functional.
FCU 500..H1
M
If the furnace temperature falls below the spontaneous
5-8 BCU 480..D1 ignition temperature (< 750°C), the FCU disconnects
STM µC
HT
18
the HT output from the electrical power supply. There is
HT
no longer an active signal at the HT inputs of the burner
6
22 23 control units. The flame signals are monitored once
BCU 480..D1 again by the UV sensor or flame rod.
µC
In the event of a fault in a temperature monitoring com-
HT ponent (e.g. sensor discontinuity, sensor short-circuit)
6
22 23 or in the event of a mains failure, the flame control task
is transferred to the burner control units.

In high temperature systems (temperature > 750°C),

the flame may be controlled indirectly via the tempera-
ture. As long as the temperature in the furnace chamber
is below 750°C, the flame must be controlled by con-
ventional methods.
If the temperature in the furnace chamber rises above
the spontaneous ignition temperature of the gas/air
mixture (> 750°C), the FCU signals to the burner con-
trol units via the fail-safe HT output that the furnace
system is in High temperature mode (HT). When the
HT input is activated, the burner control units switch to
High temperature mode. They operate without evaluat-

BCU 480 · Edition 11.19 12

Application
1.1.7 ON/OFF rotary impulse
control
For processes which require a turn-
down of more than 10:1 and/or
VAS M those which require heavy circula-
BCU 480/ tion of the furnace atmosphere to
LM..F3 ensure a uniform temperature, e.g.
PZL PZH PZ
heat treatment furnaces operating
VAS at low and medium temperatures in
DG DG VAS DG VAS the metallurgical industry.
VAS VAG
DG min DG max
With ON/OFF cyclic control, the
46
49 50 15 14 13 capacity supplied to the process is
ϑ 1 45 controlled by means of a variable
pu/2 VR..L
2 ratio of the operating time to the
µC
3 P BCU 480/ pause time. In this type of control,
>750° LM..F3
the burner output pulse frequency
FCU 500..F0
58 STM 47 48 always maintains full momentum
VAS
DL min DL Purge and results in maximum convection
in the furnace chamber, even with
M VAS VAG
regulated heating.
PZL PDZ
▼
DG DG VR..L

TE

BCU 480 · Edition 11.19 13

Application
The pneumatic ratio control sys-
tem controls the gas pressure on
the burner proportionally to the air
pressure and thus maintains a con-
VAS M stant air/gas ratio. At the same time,
BCU 480/ it acts as a low air pressure protec-
LM..F3 tion device.
PZL PZH PZ The ignition and monitoring of the
VAS
individual burners is ensured by
DG DG VAS DG VAS burner control unit BCU 480 with
VAS VAG
DG min DG max
power module LM..F3.
46
49 50 15 14 13
The centrally checked safety func-
ϑ 1 45
pu/2 VR..L
tions such as pre-purge, tightness
2
µC
test, flow detector and pressure
3 P BCU 480/
>750° switch check (gasmin., gasmax.,
LM..F3
FCU 500..F0 airmin.) are provided by the FCU 500.
58 STM 47 48
DL min DL Purge VAS

M VAS VAG
PZL PDZ

DG DG VR..L

TE

BCU 480 · Edition 11.19 14

Application
1.1.8 Modulating burner control
The centrally checked safety func-
tions such as pre-purge, setting the
valve to ignition position via a but-
terfly valve control system, tight-
VAS M ness test, flow detector and pres-
BCU 480/LM..F3 sure switch check (gasmin., gasmax.,
airmin.) are provided by the FCU 500.
66
The capacity can be adjusted con-
PZL PZH PZ
VAS tinuously by activating the control
DG DG VAS DG VAS element (analogue or 3-point step
VAS VAG signal).
DG min DG max
49 50 15 14 13 To ensure that the correct air vol-
46 45
ϑ 1 P pu/2 ume is available for ignition (start
57
2 fuel flow rate) when starting the
µC 16
3
>750° BCU 480/LM..F3 burners, the FCU sends the burner
TC start enable signal to the BCUs via
FCU 500..F0 0°➔90° 53 66
90°➔0° 54
58 STM 47 48 55 the “LDS (limits during start-up)”
VAS
DL min DL Purge output.
The circuit design of the safety
M VAS VAG
PZL PDZ
interlock and LDS outputs on the
M
FCU and the corresponding in-
DG DG
puts on the BCUs ensures that the
burners can only start if the safety
TE
interlocks and the LDS output have
enabled burner start-up.

BCU 480 · Edition 11.19 15

Application
1.1.9 PROFINET connection using bus module BCM

L1 FCU HT P

PLC BUS

PROFINET
BCU 4xx

BCU 4xx

BCU 4xx
BCM BCM BCM

1 1 1
2 2 2

The bus system transfers the control signals from the

automation system (PLC) to the BCU/BCM for starting,
resetting, controlling the air valve, purging the furnace
or for cooling and heating during operation. In the op-
posite direction, it sends operating status, the level of
the flame signal and the current program status.
Control signals that are relevant for safety, such as the
safety interlocks, purge and HT input, are wired inde-
pendently of the bus communication using separate
cables.

BCU 480 · Edition 11.19 16

Certification

2 Certification Eurasian Customs Union

Certificates – see Docuthek.
Certified to SIL and PL

The product BCU 480 meets the technical specifica-

tions of the Eurasian Customs Union.
For systems up to SIL 3 pursuant to EN 61508 and PL
e pursuant to ISO 13849
EU certified*

– 2014/35/EU (LVD), Low Voltage Directive

– 2014/30/EU (EMC), Electromagnetic Compatibility
Directive
– (EU) 2016/426 (GAR), Gas Appliances Regulation
– EN 13611:2015+AC:2016
– EN 1854:2010, class S
FM approved

Factory Mutual (FM) Research Class: 7610 “Combus-

tion Safeguards and Flame Sensing Systems”. Suitable
for applications pursuant to NFPA 86.
www.approvalguide.com

BCU 480 · Edition 11.19 17

Function

3 Function There are two control keys for the control unit:

3.1 Part designations ON/OFF

OK
Use the ON/OFF key to switch the control unit on or off.
8 9 Reset/Information
7
6 The control unit is reset to its starting position in the event of a fault
using the Reset/Information button.
1 During operation, the LED display shows the program
2 status. The flame signal intensity, the fault history and
the parameters can be called up on the display by re-
3
peatedly pressing the Reset/Information button (for
4
1 s). The parameter display is ended 60 seconds after
5
the last time the button is pressed or by switching off
10 the BCU. When the BCU is switched off, – – is displayed.
The parameters cannot be scanned when the BCU is
LED display for program status and fault messages switched off or when a fault/warning is displayed.
1 To display the program status or fault message and, in conjunction
with the Reset/Information button, to display the flame signal and the Display Information
fault history or to view and set device parameters. Flame signal intensity:
On/Off button F1 Burner 1
2 To switch the control unit on or off
F2 Burner 2
Reset/Information button
H0 Last event message
3 To reset the control unit to its starting position in the event of a fault.
System faults (internal errors) can only be acknowledged using this to to
button. H9 tenth to last event message
4 Connection for opto-adapter 001 Parameter 001
5 BCU type label to to
6 Power module, replaceable 999 parameter 999
7 Power module type label
8 Parameter chip card (PCC), replaceable
9 Bus module, replaceable
10 M5 screw terminal for burner ground

BCU 480 · Edition 11.19 18

Function

3.2 Connection diagram Explanation of symbols, see page 129 (Legend)

3.2.1 BCU 480..E1/LM 400..F3..E1

with ionization control in double-electrode
operation
Alternative flame control, see page 21 (Flame con-
trol)
Electrical connection, see page 111 (Project planning
information)

L1
P
Start 1 Start 2
A
HT LDS

L 1 2 3 4 5 6 7 35 39 40 41 BCU 480 82 81 80 85 86 87 92 91 90 95 96 97
F2
F1 (BCU..E0)
(BCU..E1)
F 3,15 A
LM 400..F3
N1
N1 F3 3,15 A UA-Sk VLuft
O
230 V
UVS

I 1 2
51 21 BM N1 N1 N1 N1 V1
N1 N1 N1 V2 N1 V3 N1 V4 N1 N1

PE L N L N L N
N PE 22 23 52 53 BM 54 24 55 25 56 26 57 27 36 58 28 37 59 29 38 60 30 61 31 62 32 63 33 65 34 66 67

V1 V2 V3 V4
pU Luft
2 PE PE PE PE PE

TC

N
PE

BCU 480 · Edition 11.19 19

Function
3.2.2 BCU 480..P3..E1/LM 400..F3..E1
with industrial plug for ionization control in double-
electrode operation
Alternative flame control, see page 21 (Flame con-
trol)
Electrical connection, see page 111 (Project planning
information)

1 HT 2 P A
2

8 7 6 5 4 3 2

16 15 14 12 11 10 9

1
PE
L1
N

16 8 14 4
6 3
6 6 7 LDS 9 10 11 12 2

L 1 2 3 4 5 6 7 35 39 40 41 BCU 480 82 81 80 85 86 87 92 91 90 95 96 97
F2
F1 (BCU..E0)
(BCU..E1)
F 3,15 A
LM 400..F3
N1
N1 F3 3,15 A UA-Sk VLuft
O
230 V
UVS

I 1 2
51 21 BM N1 N1 N1 N1 V1
N1 N1 N1 V2 N1 V3 N1 V4 N1 N1

PE L N L N L N
N PE 22 23 52 53 BM 54 24 55 25 56 26 57 27 36 58 28 37 59 29 38 60 30 61 31 62 32 63 33 65 34 66 67

15 pU V1 V2 V3 V4
2 Luft
PE PE PE PE PE
TC

BCU 480 · Edition 11.19 20

 Function
3.2.3 Flame control Pilot burner = single-electrode operation/main
In the case of UV control, use Elster UV sensors for in- burner = UVC 1:
termittent operation (UVS 5, 10) or flame detectors for Parameter I004 = 4.
continuous operation (UVC 1). BCU 480
230 V

N1 N1 N1
UVS

2 2
Pilot burner = single-electrode operation/main
1 2 1

51 21 BM PE 51 21 BM PE 51 21 BM PE
burner = ionization:
N1 PE
N1 N1 LM 400..F3
N1 PE

23 Parameter I004
52 BM= 0.
PE 22 23 BM 54 24 PE 22 23 BM 54 24 PE

230 V
N1

UVS
1
UVS 2 1 2 4 4
3 3 3
UVC 1 2 UVC 1 2
51 21 BM PE 1 1

22 23 52 BM PE
Pilot burner = UVS/main burner = ionization:
Parameter A002 ≥ 5 �A.
Parameter I004 = 5.

230 V
N1

UVS
Pilot burner = single-electrode operation/main 1 2

burner = UVS: 51 21 BM PE

Parameter A001 ≥ 5 �A. 22 23 52 BM PE

Parameter I004 = 3.

1
UVS 2
3
230 V
230 V

N1 N1 N1
UVS
UVS

1 2 1 2 1 2

E 51 21 BM PE 51 21 BM PE N1 PE
N1 51 21 BM PE

52 BM PE 22 23 52 BM PE 22 23 BM 54 24 PE 22 23 BM 5

1 1
2 UVS 2 4 4
3 3 3 3
UVC 1 2 UVC 1 2
1 1

BCU 480 · Edition 11.19 21

Function
Pilot burner = UVC/main burner = UVC:
Parameter I004 = 2.
N1
1 2

51 21 BM PE N1 PE
N1

22 23 BM 54 24 PE
UVC 1 2
1
4
3

4
3
UVC 1 2
1

Pilot burner = UVC/main burner = ionization:

Parameter I004 = 7.

N1
1 2

51 21 BM PE N1 PE
N1

22 23 BM 54 24 PE
UVC 1 2
1
4
3

BCU 480 · Edition 11.19 22

Function
3.2.4 Assignment of connection terminals
Terminal Type Designation Function
1 Start-up signal 1 Signal applied: heating (pilot burner) start; no signal: heating stop
Input for external signal (button) to reset the unit after a fault lock-out. System faults
2 Remote reset (internal errors) can only be acknowledged using this button.
If there is an active signal, the BCU opens the air actuator regardless of the status of the
3 External purge air other inputs.
External air valve control with an active signal, e.g. to supply air to the combustion chamber
for cooling. Controlled air flow is only possible in standby with deactivated start-up signal.
4 External air valve control As soon as heating operation is started (start-up signal at terminal 1), the function is
Control input interrupted.
(AC mains voltage)
5 Start-up signal 2 Signal applied: heating (main burner) start; no signal: heating stop
Feedback High temperature operation feedback input. When the input is activated, the BCU operates
6 without evaluating the flame signal. The safety function of the device’s internal flame
High temperature operation control system is deactivated.
Controller enable/Emergency
35 Connection for higher-level safety devices and interlocks (e.g. emergency stop)
stop
Feedback signal of the control element position for ignition capacity. As soon as a signal is
39 LDS query present, the BCU completes a burner start, restart or start-up attempt.
40 Safety circuit input Feedback from actuator Feedback input for ignition position
41 (AC mains voltage) Feedback from actuator Feedback input for maximum capacity
22 Flame signal 1 (pilot burner) Connection for flame rod/UV sensor
Input (�A)
23 Flame signal 2 (main burner) Connection for flame rod/UV sensor
Power supply
51, 21 (AC mains voltage) Ignition Connection for an ignition transformer
52 Voltage supply for UV sensor UVS for burner 1 (pilot burner)
Output
(AC mains voltage) UV sensor
53 Voltage supply Voltage supply for UV sensor UVS for burner 2 (main burner)

UV sensor for continuous

54, 24 operation Voltage supply for UV sensor UVC 1
55, 25 Voltage supply
56, 26 Active mains voltage Voltage supply for actuators and sensors
57, 27
58, 28

BCU 480 · Edition 11.19 23

Function

Terminal Type Designation Function

Voltage supply +
safety circuit input Connection for the sensor of the valve proving system (pressure switch for tightness test or
59, 29 Valve proving system POC switch for checking the closed position)
(AC mains voltage)
60, 30 Gas valve V1 Connection for gas valve V1
61, 31 Valve outputs Gas valve V2 Connection for gas valve V2
62, 32 (AC mains voltage) Gas valve V3 Connection for gas valve V3
63, 33 Gas valve V4 Connection for gas valve V4
LM..F1:
64, 65, Capacity control Connection for capacity control using an actuator
66, 67 Outputs
LM..F3: (AC mains voltage)
65, 66, Air valve control Connections for air valves
67
80, 81 Fault signal Contact between terminals 80/81 and 82 closes in the event of a BCU fault lock-out.
82 (parameter-dependent function)
95 Contact between terminals 95 and 96 closes once the operating signal has been received
Ready for operation (parameter- from burner 1.
96, 97 dependent function) Contact between terminals 95 and 97 closes once the operating signal has been received
Floating contact from burner 2.
85
Parameter-dependent function Contact can be adjusted depending on parameter I054
86, 87
90, 91
Parameter-dependent function Contact can be adjusted depending on parameter I051
92

BCU 480 · Edition 11.19 24

Function

3.3 BCU 480 program sequence ▼

Switch on BCU 480 03 Flame proving period 1 tFS1 running (A095)

▼ ▼
In the event of flame failure:
In the event of fault signal: reset Fault lock-out
▼ ▼
00 Safety interlocks 04 Pilot burner operation signalling contact closes,
Start-up position/Standby valve for 2nd gas stage opens and
min. operating time tB starts to elapse (A061)
▼ ▼
Flame simulation check In the event of flame failure:
(if parameter A003 = 0) restart or fault lock-out
▼ ▼
P0 External actuation of the air valve for purging A4 External actuation of the air valve for capacity control
▼ ▼
A0 External actuation of the air valve for cooling
05 Main burner start-up with start-up signal (start 2)
▼ ▼
01 Pilot burner start-up with start-up signal (start 1) Wait until the min. pause has elapsed (parameter A062)
▼ ▼
Wait until the min. pause has elapsed (parameter A062) Flame simulation check
(if parameter A003 = 1)
▼
Flame simulation check ▼
(if parameter A003 = 1) Safety time 2 tSA2 (A096) running,
06
▼ ignition in process,
valves for 2nd gas stage open and
02 Safety time 1 tSA1 (A094) running, min. operating time starts to elapse (A061)
ignition in process,
valves for 1st gas stage open and ▼
min. operating time starts to elapse (A061) If no flame detected:
max. 3 start-up attempts (A008)
▼ or fault lock-out
If no flame detected:
max. 3 start-up attempts (A007) ▼
or fault lock-out

BCU 480 · Edition 11.19 25

Function

07 Flame proving period 2 tFS2 running (A097)

▼
In the event of flame failure:
Fault lock-out
▼
08 Main burner operation signalling contact closes
▼
In the event of flame failure:
restart or fault lock-out
▼
A8 External actuation of the air valve for capacity control

08 Controlled shut-down via start-up signal

▼
00 If min. operating time tB has elapsed:
operation signalling contact opens,
gas valves close and
min. operating time starts to elapse (A061)

BCU 480 · Edition 11.19 26

Air control

4 Air control
A central protective system such as the FCU 500 takes
over air control. It monitors the static air pressure as
well as the air volume required for pre-purge, start-up
and after the furnace has been shut down. The air ac-
tuators (BCU with LM..F1 = actuator IC 40, BCU with
LM..F3 = air valve) are actuated for this purpose by the
capacity control system of the BCU.
After being enabled by the protective system, the BCU
can start the burners. The capacity is controlled during
operation by an external temperature control system.

VAS M

BCU 480..F3
BCU/LM..F3

PZL PZH PZ
VAS

DG DG VAS DG VAS
VAS VAG
DG min DG max
49 50 15 14 13
46
45
ϑ 1
pu/2 VR..L
2
µC
3 P BCU 480..F3
BCU/LM..F3
>750°
FCU
FCU 500..F0
500..F0
58 STM 47 48
DL min DL Purge VAS

M VAS VAG
PZL PDZ

DG DG VR..L

TE

BCU 480 · Edition 11.19 27

Air control

4.1 Capacity control The protective system (e.g. FCU 500) starts the pre-
purge time if there is adequate air flow. After the elapse
4.1.1 BCU..F1
of the pre-purge time, the control element moves to the
Process control (PCC) ignition position. Once the protective system (termi-
FCU 500 PLC
mA nal 35, safety interlocks) has issued the enable signal,
the pilot and main burners can be started by the start-
P HT LDS Start 1 A Start 2 up signals at terminals 1 and 5. The control element
BCU 480/ 3 6 35 39 1 2 4 5
81
can be activated to control the burner’s capacity de-
LM..F1 82
pendent on parameters A048 and A049.
µC 95
96
23 ▼
40 41 65 66 60 61 62 64 22

V3

V1
V2

VAS VAG S
UV

4 7 VAS 1
16 DI 1 DI 2
12
µC V4
18
M IC 40

BVA

The BCU with LM..F1 activates a control element via

the outputs for capacity control (terminals 64 to 67)
for purging, cooling or starting the burner. This control
element moves to the required position for the relevant
operating situation.
As soon as there is a purge signal at terminal 3 of BCU,
the control element is activated by the outputs for ca-
pacity control to approach the position for pre-purge.

BCU 480 · Edition 11.19 28

Air control
Modulating control
Parameter I020 = 2, A048 = 2
After the operating signal has been received from the
burner, the BCU issues the controller enable signal via
the output at terminals 65 and 66. Access to the con-
trol element is thus transferred to an external tempera-
ture controller. The temperature controller controls the
burner capacity (air volume) on the basis of the required
temperature.
Detailed information about parameter I020, see from
page 99 (Air actuator).
Staged control
Parameter A048 = 0, 1 or 2
Depending on parameters A048 and A049, the con-
trol element may be activated either by the program
or externally via the input at terminal 4, see also from
page 86 (Air actuator control).

BCU 480 · Edition 11.19 29

Air control
4.1.2 BCU..F3 interlocks) has issued the enable signal, the burner can
V1 V2
be started by the start-up signal at terminal 1. The gas
valves for the 1st stage are opened and the burner is
VAS VAG
VAS 1
ignited (on the BCU..C1 after a successful valve check).
V4 After the operating signal has been received from the
Process control (PCC) burner, the gas valve for the 2nd stage opens.
FCU 500 PLC
Staged control
Parameter A048 = 0, 1 or 2
Depending on parameters A048 and A049, the con-
ϑ1 A ϑ2
trol element may be activated either by the program
1 4 2
5 or externally via the input at terminal 4, see also from
BCU 480/LM..F3
35 60 page 86 (Air actuator control).

S
UV
61
µC 63
HT 6
23
P 3 22

10
VR..L

The BCU with LM..F3 activates an air valve for purging,

cooling or starting the burner. The required air capacity
is released by the air valve.
As soon as there is a purge signal at terminal 3 of the
BCU with LM..F3, the air valve is activated by the output
at terminal 65. The protective system (FCU 500) starts
the pre-purge time if there is adequate air flow. After the
elapse of the pre-purge time, the air valve closes for ig-
nition. Once the protective system (terminal 35, safety

BCU 480 · Edition 11.19 30

Valve proving system

5 Valve proving system 5.1 Tightness control

The BCU 500..C1 is fitted with an integrated valve prov- The aim of the tightness control is to identify an inad-
ing system. This allows either the tightness of the gas missible leak on one of the gas solenoid valves and to
solenoid valves and the pipework between them to be prevent burner start. Gas solenoid valves V1 and V2 are
checked (tightness test) or the closed position of a so- tested as is the pipework between the valves.
lenoid valve (proof of closure function) to be checked. pu
Once the test has been carried out successfully, the V1 2 V2
PZ
burner enable signal is issued.
For details, see following chapter Tightness control and
page 39 (Proof of closure function). pu Vp1

European standards EN 746-2 and EN 676 stipulate

tightness controls for capacities over 1200 kW (NF-
PA 86: from 117 kW or 400,000 Btu/h).
The tightness control function satisfies the require-
ments of EN 1643, EN 746-2, ISO 13577-2 and NF-
PA 86 for valve proving systems.

BCU 480 · Edition 11.19 31

Valve proving system
5.1.1 Test instant V3
VAS 1
Depending on the parameter setting, the tightness
control checks the tightness of the pipework and the V1
V2
PZH
gas solenoid valves before each start-up and/or after
each shut-down of the burner, see page 90 (Valve
VAS VAG
Vp1
proving system). V4

The gas line is always safeguarded by a gas solenoid VAS 1

valve during this check. pu/2
38 60 61 62 63
Before burner start-up
BCU 480..C0F3
The valve check is started when the start-up signal is
present at terminal 1. The BCU checks the tightness µC

of the gas solenoid valves and the pipework between

the valves. The gas line is always safeguarded by a gas
solenoid valve during this check. The pilot burner is ig-
nited when pre-purge is ended and the tightness has
been checked successfully.
After burner shut-down
After the burner has been shut down, the BCU checks
the tightness of the gas solenoid valves and the pipe-
work between them. Once the test has been carried out
successfully, the next burner start is enabled.
The BCU always conducts a tightness test if mains volt-
age is available or if it is reset after a fault lock-out.
An additional bypass/relief valve must be installed in
gas sections with an air/gas ratio control. This ensures
that the test volume Vp1 can be vented during the tight-
ness test with the air/gas ratio control closed.

BCU 480 · Edition 11.19 32

Valve proving system
5.1.2 Program sequence
The tightness test starts by checking the external pres-
START sure switch. If pressure pZ > pu/2, program A starts.
If pressure pZ < pu/2, program B starts, see page 34
+ p –
pZ > u (Program B).
Programm A 2 Programm B
V1 V2
Program A
Valve V1 opens for the opening time tL set in parame-
tL = A059 V1 V2 tL = A059
PZ ter A059. V1 closes again. During the measurement time
pu/2
V1 V2 tM, the tightness control checks the pressure pZ between
pz the valves.
tM = A056 tM = A056 If pressure pZ is less than half the inlet pressure pu/2,
valve V2 is leaking.
p – + p
pZ > u pZ > u If pressure pZ is greater than half the inlet pressure pu/2,
2 2
+ – valve V2 is tight. Valve V2 is opened for the set opening
V2 OK V2 V1 V1 OK time tL . V2 closes again.
During the measurement time tM, the tightness control
V2 V1
checks the pressure pZ between the valves.
tL = A059 tL = A059 If pressure pZ is greater than half the inlet pressure pu/2,
valve V1 is leaking.
V2 V1 If pressure pZ is less than half the inlet pressure pu/2,
valve V1 is tight.
tM = A056 tM = A056
The tightness test can only be performed if pressure pd
p + – p downstream of V2 is around atmospheric pressure and
pZ > u pZ > u
2 2 the volume downstream of V2 is at least 5 × higher than
– +
the volume between the valves.
V1 OK V1 V2 V2 OK
▼

BCU 480 · Edition 11.19 33

Valve proving system
Program B
Valve V2 opens for the set opening time tL . V2 closes
START again. During the measurement time tM, the tightness
control checks the pressure pZ between the valves.
+ p –
pZ > u If pressure pZ > pu/2, valve V1 is leaking.
Programm A 2 Programm B
V1 V2 If pressure pZ < pu/2, valve V1 is tight. Valve V1 is
opened for the set opening time tL . V1 closes again.
tL = A059 V1 V2 tL = A059
PZ During the measurement time tM, the tightness control
pu/2
V1 V2 checks the pressure pZ between the valves.
pz If pressure pZ < pu/2, valve V2 is leaking.
tM = A056 tM = A056
If pressure pZ > pu/2, valve V2 is tight.
p – + p The tightness test can only be performed if pressure pd
pZ > u pZ > u
2 2 downstream of V2 is around atmospheric pressure and
+ – the volume downstream of V2 is at least 5 × higher than
V2 OK V2 V1 V1 OK the volume between the valves.

V2 V1

tL = A059 tL = A059

V2 V1

tM = A056 tM = A056

p + – p
pZ > u pZ > u
2 2
– +
V1 OK V1 V2 V2 OK

BCU 480 · Edition 11.19 34

Valve proving system
5.1.3 Test period tP
Depending on the burner capacity, the tightness of the
gas solenoid valves must be checked in accordance
with the relevant application standard, e.g. EN 676,
EN 746, NFPA 85 and NFPA 86.

V1 V2
PZ
pd

pu pz Vp1

61 60
38
pu/2
ϑ 1
P
3
µC
The test period
2 tP is calculated
>750° from:
TC
– Opening BCU
times tL for V1 and V2,
560..C1
– Measurement times36tM 37 for V1 and V2.

tP [s] = 2 x tL + 2 x tM

PZL PDZ
5.1.4 Opening time tL
Standard EN 1643:2000 allows a maximum opening
time of 3 s for the tightness test if the main gas valves
are actuated directly. If gas can flow into the combus-
tion chamber when a valve is opened, the gas volume
must not exceed 0.083% of the maximum flow rate.

BCU 480 · Edition 11.19 35

Valve proving system
5.1.5 Measurement time tM The BCU tightness control makes it possible to check
The sensitivity of the tightness control in the BCU can a specific leakage rate QL . Within the European Union,
be adjusted for each individual system by adapting the the maximum leakage rate QL is 0.1% of the maximum
measurement time tM. The longer the measurement flow rate Q(N)max. [m3/h].
time tM, the greater the sensitivity of the tightness
control. The measurement time is set using parameter Q(N) max. [m3/h] x 1000 [l/h]
Leakage rate QL [l/h] =
A056 to a value between 3 and 3600 s, see page 91 1000 x 1 [m3/h]
(Measurement time for Vp1).
▼
The required measurement time tM is calculated from:
Inlet pressure pu [mbar]
Leakage rate QL [l/h]
Test volume Vp1 [l]
Calculation of the test volume, see page 37 (Test volume Vp1)

For one test volume Vp1 between 2 gas solenoid

valves
Adjustable using parameter A056

tM [s] = ( 2 x pu x Vp1
DN  )
For a large test volume Vp1 with reduced testing
time
Adjustable using parameter A056

tM [s] = ( 0.9 x pu x Vp1

QL  )
Conversion into US units, see page 125 (Converting
units)
Leakage rate

BCU 480 · Edition 11.19 36

Valve proving system
Test volume Vp1 The measurement time required for the test volume Vp1
Test volume Vp1 is calculated from the valve volume V V, must be set on the basis of the calculation using pa-
added to the volume of the pipe VR for each additional rameter A056.
metre in length L. For the calculation, see page 38 (Calculation exam-
ples).

L Vp1 = VV + L x VR
Valves Pipe
Volume per metre
Type Volume V V [l] DN VR [l/m]
VAS 1 0.08 10 0.1
VAS 2 0.32 15 0.2
VAS 3 0.68 20 0.3
VAS 6 1.37 25 0.5
VAS 7 2.04 40 1.3
VAS 8 3.34 50 2
VAS 9 5.41 65 3.3
VG 10 0.01 80 5
VG 15 0.07 100 7.9
VG 20 0.12 125 12.3
VG 25 0.2 150 17.7
VG 40/VK 40 0.7 200 31.4
VG 50/VK 50 1.2 250 49
VG 65/VK 65 2
VG 80/VK 80 4
VK 100 8.3
VK 125 13.6
VK 150 20
VK 200 42
VK 250 66

BCU 480 · Edition 11.19 37

 Valve proving system
Calculation examples Measurement time for one test volume Vp1
2 valves VAS 665,
2 x 50 mbar x 32.45 l
distance L = 9.5 m, tM [s] =  = 16.23 s
200 l/h
inlet pressure pu = 50 mbar,
Set the next highest value (20 s) using parameter 56, see page 91
max. flow rate Q(N)max. = 200 m3/h. (Measurement time for Vp1).

Q(N) max. =
VAS 665 VAS 665
200 m3/h

pu Vp1
= 50 mbar
62 61 60 9,5 m
DN65
1
3
µC
2 >750°
TC
BCULeakage
570..C1rate 200 m3/h x 1000 l/h
Q47 = = 200 l/h
L 48 1000 x 1 m3/h
Test volume Vp1 = 1.1 l + 9.5 m x 3.3 l/m = 32.45 l,
see page 37 (Test volume Vp1)
PZL PDZ

BCU 480 · Edition 11.19 38

Valve proving system

5.2 Proof of closure function As soon as the BCU has opened valve V1, it queries the
The proof of closure function monitors the function of open position of the valve via the POC switch. If a sig-
the gas solenoid valve V1. The proof of closure function nal is still being received at terminal 38 from the POC
can be activated by setting parameter A051 to 4, see switch after a timeout time of 10 s, the BCU performs a
page 90 (Valve proving system). fault lock-out with fault message “E c8”.

A limit switch on gas solenoid valve V1 signals the

closed position of the valve to the BCU (terminal 38) for
this purpose.

V1 V2
PZL PZH GZL

36 37 61 60
38
ϑ 1
P
2
µC
By checking the closed position
>750° using the proof of clo-
sure function, the BCU complies with the requirements
TC
BCU 46x..C1
of NFPA 85 58(Boiler and Combustion Systems Hazards
47 48
Code) and NFPA 86 (Standard for Ovens and Furnaces).
M
5.2.1 Program sequencePZL PDZ
When the start-up signal is received at terminal 1, the
BCU checks that valve V1 is in its closed position using
the POC switch. If a signal is not received at terminal 38
from the POC switch after a timeout time of 10 s (valve
V1 is closed), the BCU performs a fault lock-out with
fault message “E c1”.

BCU 480 · Edition 11.19 39

BCSoft

6 BCSoft The current version of the engineering tool BCSoft is

available at www.docuthek.com.
BCSoft is an engineering tool for PCs with a Windows
operating system. BCSoft (from V4xx) makes it possible In addition to the engineering tool BCSoft, an opto-
to set device parameters in order to adjust them to the adapter with USB connection or a Bluetooth adapter is
specific application. BCSoft logs and archives the device required for data transfer between the PC and BCU. If
parameters. In addition, BCSoft offers further functions. the burner control unit BCU is operated in conjunction
In conjunction with Manual mode, the process values with the bus module BCM 400, communication via
overview provides commissioning support in order to fa- Ethernet is possible, see also page 116 (Accessories).
cilitate the commissioning process. In the event of faults
or service interventions, details on troubleshooting can
be derived from the device statistics and the fault history.

BCU 480 · Edition 11.19 40

Fieldbus communication

7 Fieldbus communication The signals from the devices are read into the controller
PROFIBUS DP, PROFINET and EtherNet/IP are man- cyclically. There, they are processed and then output to
ufacturer-independent, open standards for industrial the devices again.
network communication. They cover the requirements
for automation technology (manufacturing automa-
tion, process automation, drive applications without
functional safety). They are bus variants for fieldbus
communication optimized for speed and low connec-
tion costs.

L1 FCU HT P

SPS BUS

PROFINET
BCU 4xx

BCU 4xx

BCU 4xx

BCM BCM BCM

1 1 1
2 2 2

The basic function of fieldbus communication is the

exchange of process and required data between a con-
troller (e.g. a PLC) and several distributed devices (e.g.
BCM with BCU).

BCU 480 · Edition 11.19 41

Fieldbus communication

7.1 BCU and bus module BCM munication direct between the BCU and the protective
The optional bus module BCM 400 is required to in- system (e.g. FCU).
tegrate the BCU in a standardized fieldbus system
FCU HT P
(PROFIBUS, PROFINET or EtherNet/IP).
PLC BUS PROFINET,
Control signals (for start and reset, for example), signal
PROFIBUS,
states from the device inputs and outputs and informa- ETHERNET/IP
tion about the device status (operating states, flame
BCU L1,

BCM
signal and current program step), warnings and faults Temperature
controller
can be transferred simultaneously via the bus module
ϑ
between the BCU and PLC.

0 ➔ 90°
90° ➔ 0
The bus module BCM 400..B1 has a 9-pin D-Sub con- 3PS 66 67 65
nection socket on the front, while the bus modules
BCM 400..B2 and B3 have two RJ45 connection sock-
ets on the front for connection to the fieldbus. The
RJ45 connection sockets are combined with an internal M

2-port switch. This allows the BCM 400 together with

the BCU to be integrated in various network topologies
(star, tree or line topology). Requirements such as Auto
All network components which connect the automation
Negotiation and Auto Crossover are satisfied.
system and the field devices must be certified for the
relevant fieldbus use.
For information on planning and the structure of a net-
work and the components to be used (e.g. cables, lines
and switches)
for PROFINET and PROFIBUS, see www.profibus.com,
for EtherNet/IP, see www.odva.org.

Safety-related signals and interlocks (e.g. safety inter-

lock) must be wired independently of the fieldbus com-

BCU 480 · Edition 11.19 42

Fieldbus communication

7.2 Configuration, planning

Before commissioning, the bus module must be config-
ured for data exchange with the fieldbus system using
an engineering tool or BCSoft.
To do so, fieldbus communication must be enabled on
the control unit with connected bus module BCM and
the code switches on the BCM set, see also page 95
(Fieldbus communication).
7.2.1 Device master data file (GSD), electronic data
sheet (EDS)
The technical properties of a device are described by
the manufacturer for PROFIBUS and PROFINET in a
device master data file (GSD file) or for EtherNet/IP
in an electronic data sheet (EDS). The GSD/EDS file
is required to integrate the device (BCU) in the con-
figuration of the PLC. The GSD/EDS file contains the
device image, the communications properties and all
fault messages from the device in text form which are
important for configuring the PROFINET network and
the data exchange. Modules defined in the GSD/EDS
file may be selected for configuration to integrate the
device. The GSD/EDS file for the bus module can be
obtained from www.docuthek.com. The steps required
to integrate the file are described in the instructions for
the engineering tool for your automation system.

BCU 480 · Edition 11.19 43

Fieldbus communication

7.3 PROFINET, EtherNet/IP

In addition to cyclic data exchange, the PROFINET and
EtherNet/IP fieldbus systems also provide acyclic data
exchange for events which are not constantly repeated
such as sending device statistics. In the event that the
bus communication is faulty or interrupted and during
initialization of the bus communication after switching
on, the digital signals are interpreted as “0”.
7.3.1 Modules for process data
All modules required for data exchange between the
PLC and the burner control unit BCU are shown in the
following table.
Module (PROFINET) Slot
Inputs (BCU ➔ PLC)
1
Outputs (PLC ➔ BCU)
Burner 1 flame signal 2
Burner 2 flame signal 3
Status signal 4
Fault and warning signals 5
Remaining times 6
Temperature 7
Input information (via terminal and bus) 9
Output information (via terminal and bus) 10

BCU 480 · Edition 11.19 44

Fieldbus communication
Inputs/Outputs Bit Byte n Byte n+1 Format
The digital input and output signals from the burner 0 Reset1) Auxiliary gas BOOL
control unit BCU are included in this module. 1 Burner 1 start1) Optional output BOOL
2 External air ON1) Cooling air valve BOOL
Input bytes (BCU ➔ PLC) 3 Pre-purge ON Free BOOL
The input bytes describe the digital signals which are 4 Burner 2 start1) Free BOOL
transferred from the BCU to the digital inputs of the 5 Free Free BOOL
PLC. The digital signals take up 3 bytes (24 bits). 6 Free Free BOOL
7 Free Free BOOL
Bit Byte n Byte n+1 Byte n+2 Format 1) Terminals 1 to 41 (dependent on parameters I061 to I074) can
0 Burner 1 operating be wired parallel to the bus communication.
Free Free BOOL
signal
1 Burner 2 operating ▼
Free Free BOOL
signal
2 BCU system fault Air ON Free BOOL
3 Fault lock-out Pre-purge ON Free BOOL
4 Safety shut-down HT ON Free BOOL
Ready for
5 Warning Free BOOL
operation
Burner 1 flame
6 ON Free BOOL
signal
Burner 2 flame
7 Manual mode Free BOOL
signal

Output bytes (PLC ➔ BCU)

The output bytes describe the digital signals which
are output by the PLC to the BCU. The digital signals
to control the burner control unit BCU occupy 2 bytes
(16 bits).
Terminals 1 to 41 (dependent on parameters I061 to
I074) can be wired parallel to the bus communication.
This allows the BCU to be controlled using the digital
signals of the bus communication or the inputs at the
terminals.

BCU 480 · Edition 11.19 45

Fieldbus communication

Burner 1 flame signal (BCU ➔ PLC) Status signal (BCU ➔ PLC)

The flame signal for burner 1 is transferred from the This module transfers the status signals from the
BCU to the PLC as an analogue value using this module. BCU to the PLC. The status signals occupy one byte
The flame signal occupies one byte with values from 0 (0 to 255). Every status signal is allocated a code. The
to 255 (= flame signal from 0 to 25.5 µA). allocation is described in the code table “BusCommuni-
Bit Byte n Data type Format Value cation_BCU4_R2.xlsx”.
0 Bit Byte n Data type Format Value
1 0
2 1
3 0 – 2551) 2
Burner 1 flame signal Byte DEC
4 (0 – 25.5 μA)
3
5 Status messages Byte DEC 0 – 2551)
4
6 5
7 6
1) See code tables “BusCommunication_BCU4_R2.xlsx” at www. 7
docuthek.com. 1) See code tables “BusCommunication_BCU4_R2.xlsx” at www.
docuthek.com.
Burner 2 flame signal (BCU ➔ PLC)
The flame signal for burner 2 is transferred from the ▼
BCU to the PLC as an analogue value using this module.
The flame signal occupies one byte with values from 0
to 255 (= flame signal from 0 to 25.5 µA).
Bit Byte n Data type Format Value
0
1
2
3 0 – 2551)
Burner 2 flame signal Byte DEC
4 (0 – 25.5 μA)
5
6
7
1) See code tables “BusCommunication_BCU4_R2.xlsx” at www.
docuthek.com.

BCU 480 · Edition 11.19 46

Fieldbus communication

Fault and warning signals (BCU ➔ PLC) Remaining times (BCU ➔ PLC)
The fault and warning signals are transferred from the This module transfers the remaining times of various
BCU to the PLC using this module. The fault and warn- processes from the BCU to the PLC. The remaining
ing signals each occupy one word. time occupies one word.
The same allocation table applies to the fault signals Bit Byte n Byte n+1 Data type Format Value
and the warning signals. 0
1
Bit Byte n Byte n+1 Data type Format Value 2
0 3 0 – 6554
Remaining times Word DEC
1 4 (0 – 6554 s)
2 5
3 6
Fault signals Word DEC 0 – 6555351) 7
4
5
6
7
Temperature (BCU ➔ PLC)
Bit Byte n+2 Byte n+3 Data type Format Value
This module transfers the internal device temperature.
0
1 The temperature occupies one word.
2
Bit Byte n Byte n+1 Data type Format Value
3
Warning signals Word DEC 0 – 6555351) 0
4
5 1
6 2
7 3 0 – 6554
Temperature Word DEC
1) 4 (0 – 6554 K)
See code tables “BusCommunication_BCU4_R2.xlsx” at www.
docuthek.com. 5
6
7

BCU 480 · Edition 11.19 47

Fieldbus communication

BCU input information (BCU ➔ PLC)

This module transfers the signal states of the digital inputs on the BCU to the PLC.
Transfer via
Input terminals K-SafetyLink NFS bus
Bit Byte n Byte n+1 Byte n+2 Byte n+3 Byte n+4 Format
0 Terminal 1 Terminal 36 Safety interlocks (limits) Reset Auxiliary gas BOOL
1 Terminal 2 Terminal 37 LDS Burner 1 start Optional output BOOL
2 Terminal 3 Terminal 38 High temperature Air Cooling air valve BOOL
3 Terminal 4 Terminal 39 Purge Purge Free BOOL
4 Terminal 5 Terminal 40 Free Burner 2 start Free BOOL
5 Terminal 6 Terminal 41 Free Flameless operation Free BOOL
6 Terminal 7 Free Free Open control element Free BOOL
7 Terminal 35 Free Free Close control element Free BOOL

BCU output information (BCU ➔ PLC)

This module transfers the signal states of the digital outputs on the BCU (via output terminals and bus) to the PLC.
Bit Byte n Byte n+1 Byte n+2 Byte n+3 Byte n+4 Byte n+5 Format
Burner 1 operating Control element to
0 Terminal 60 Terminals 80/81, 82 Ready Free BOOL
signal max. position
Burner 2 operating Control element to
1 Terminal 61 Terminals 85/86, 87 Purge ON Free BOOL
signal closed position
2 Terminal 62 Terminals 90, 91/92 Operating signal BCU system fault Air ON Free BOOL
3 Terminal 63 Terminals 95/96 Free Fault lock-out Purge ON Free BOOL
4 Terminal 64 Terminals 95/97 Free Safety shut-down HT ON Free BOOL
5 Terminal 65 Terminal 51 Free Warning Ready Free BOOL
6 Terminal 66 Free Free BCU ON Burner 1 flame Free BOOL
7 Terminal 67 Free Free Manual mode Burner 2 flame Free BOOL

BCU 480 · Edition 11.19 48

Fieldbus communication
7.3.2 Device parameters and statistics
With the help of acyclic communication between the
PLC and BCU, it is possible to read information on pa-
rameters, statistics and fault history on an event basis.
PROFINET EtherNet/IP
Description
Index Instance Attribute
Parameters 1001 1
Counter statistics 1002 2
1 (faults)
Fault/warning statistics 1003 3
2 (warnings)
Operator statistics, counters 1004 4
1 (faults)
Operator statistics, faults/warnings 1005 5
2 (warnings)
Event history 1006 6
Power module statistics 1007 7
Extreme values statistics 1008 8
Time counter statistics 1009 9
Operator statistics, extreme values 1010 10
Operator statistics, time counters 1011 11
The available data records differ in terms of their in-
dexes (PROFINET) or instances (EtherNet/IP). The
contents and description of the indexes/instances
are described in the code table “BusCommunication_
BCU4_R2.xlsx” (download from www.docuthek.com).

BCU 480 · Edition 11.19 49

Fieldbus communication

7.4 PROFIBUS I/O bytes: the programmer can choose the data to be
transferred.
Input bytes (BCU ➔ master)
Inputs Outputs
Bit Byte 0 Byte 1 Byte 2 Byte 3 Byte 4
480 basic I/O 1 byte 1 byte
0 Reset
480 standard I/O 5 bytes 1 byte

See table on page 51 (Program

1 Start 1
Baud rate: up to 1500 kbit/s.

Burner 1 flame signal

Burner 2 flame signal

2 Air ON

step/status)
The max. range per segment depends on the baud rate:

0 – 25.5 µA

0 – 25.5 µA
3 Purge ON

255 steps

255 steps
Free

Auxiliary gas/ Baud rate [kbit/s] Range [m]

4 Start 2 93.75 1200
5 Free 187.5 1000
6 Free 500 400
7 Free 1500 200
The specified ranges can be increased by using repeat-
BCU 480 basic I/O ers. No more than three repeaters should be connected
in series.
BCU 480 standard I/O
The specified ranges relate to bus cable type A (2-core,
Output bytes (master ➔ BCU)
shielded and twisted), e.g.
Bit Byte 0 Siemens, Order No. 6XV1830-0EH10, or
0 Reset Lapp cable unitronic, Order No. 2170-220T.
1 Start 1
2 Cooling
3 Purge
4 Start 2
5 Free
6 Free
7 Free

BCU 480 · Edition 11.19 50

Program step/status

8 Program step/status
DISPLAY1) Program step/status
00 Start-up position/Standby
A0 Cooling2)
P0 Pre-purge
H0 Delay
01 Minimum pause time tMP
A1 Pre-ventilation2)
0 “No flow” state check of low air pressure protection device
1 Low air pressure protection check
A Approaching minimum capacity/closed position2)
A Approaching maximum capacity2)
P0 Pre-purge
P1 Pre-purge
A   Approaching ignition capacity2)
HX Delay (in program step X)
H2 Delay
Valve check
02 Safety time 1
A2 Safety time 1 (with air)
03 Flame proving period 1 tFS1
A3 Flame proving period 1 tFS1 (with air)
04 Burner 1 operation/controller enable
A4 Burner 1 operation/controller enable (with air)
H4 Delay
05 Burner 2 waiting time
A5 Delay

BCU 480 · Edition 11.19 51

Program step/status

DISPLAY1) Program step/status

H5 Delay time during burner 2 waiting time
06 Safety time 2
A6 Safety time 2 (with air)
07 Flame proving period 2
A7 Flame proving period 2 (with air)
08 Burner 2 operation
A8 Burner 2 operation (with air)
H8 Delay
P9 Post-purge
Data transfer (programming mode)
 – – Device Off
1) In Manual mode, four dots flash on the display.
2) Air actuator (control element/valve) is open.

BCU 480 · Edition 11.19 52

Fault signalling

9 Fault signalling
Fault message (blinking) DISPLAY Description
Burner 1 flame simulation E 01 Flame simulation/Flame signal before ignition
No flame after safety time 1 E  02 No flame formation to end of 1st safety time
Flame failure during flame proving period 1 tFS1 E  03
Flame failure during burner 1 operation E  04 Flame failure during operation
Burner 2 flame simulation E  05 Flame simulation/Flame signal before ignition
No flame after safety time 2 E  06 No flame formation to end of 2nd safety time
Flame failure during flame proving period 2 tFS2 E  07
Flame failure during burner 2 operation E  08 Flame failure during operation
Too many remote resets E  10 Remote reset activated > 5 × in 15 min.
Too many restarts for burner 1 E 11 > 5 restarts in 15 minutes
Too many restarts for burner 2 E  12 > 5 restarts in 15 minutes
“Maximum capacity” and “Ignition capacity” position feedback
Simultaneous activation (terminals 40 and 41) E 21 from butterfly valve set simultaneously
Actuator wiring (terminals 65 – 67) E  22 Faulty wiring of terminals 65 – 67
Maximum or ignition capacity is not constantly signalled back to
Actuator feedback (terminals 40, 41) E  23 terminal 40 or 41
“Open actuator” and “Close actuator” bus signals set
Simultaneous Min./Max. bus command E  24 simultaneously
Non-fail-safe parameters (NFS) inconsistent E  30 NFS parameter range is inconsistent
Fail-safe parameters (FS) inconsistent E 31 FS parameter range is inconsistent
Mains voltage E  32 Operating voltage too high/low
Faulty parameterization E  33 Parameter set contains illegal settings
Faulty actuation of the air valve. Voltage is applied to the outputs
Air valve control defective E  34 at terminals 65 – 67 for the air valve.
Incompatible bus module E  35 Bus module does not support the selected function.
Relay contact fault caused by defective relay contacts, EMC
Power module defective E  36 influence, by applying voltage to outputs or by an incorrect load
module
▼
BCU 480 · Edition 11.19 53
Fault signalling

Fault message (blinking) DISPLAY Description

Fuse defective E  39 Device fuse F1 is defective
Inlet valve(s) leaking E  40 Leak found on inlet valve
Outlet valve(s) leaking E 41 Leak found on outlet valve
Pressure switch/gas valve wiring E  44
Gas valve wiring E  45 Reversed valve connection
Safety interlock failure  51
Permanent remote reset  52 Remote reset input activated > 10 s
Timing cycle too short  53 Minimum timing cycle not observed
Faulty feedback signal of the control element position for ignition
Waiting for ignition position (LDS)  54 capacity
Incorrect voltage supply to terminal 6 E  57 Flameless mode without HT signal
Internal error E  80 Flame amplifier error/Device error
Internal error E  89 Error in processing internal data
Flame amplifier or fuses defective E 91 Check the wiring and fuses
Direct voltage is connected or signal inputs and L are connected
Irregularities in the power supply E  92 to different phases
Internal error E  94 Error at digital inputs
Internal error E  95 Error at digital outputs
Internal error E  96 Error when checking the SFR
No PCC, power module error E  97 Insert compatible PCC, rectify power module contact error
Internal error E  98 Error when writing to the EEProm
emBoss E  99 Shut-down without application error
Minimum capacity not reached E  A Position for minimum capacity has not been reached after 255 s
Maximum capacity not reached E  A Position for maximum capacity has not been reached after 255 s
Ignition capacity not reached E  A   Position for ignition capacity has not been reached after 255 s
Communication with bus module E  E Bus module fault
Parameter chip card (PCC)  E  C C Incorrect or defective PCC
▼
BCU 480 · Edition 11.19 54
Fault signalling

Fault message (blinking) DISPLAY Description

POC valve open E   1 No input signal for closed valve
POC valve closed E  8 Valve not open
Fault Air monitor “no flow” state check. The signal from the
Air monitor “no flow” state E 0 pressure switches is received at terminal 36 or 37 before the air
actuator is opened.
Low air pressure E  1 Fault Air monitor operating check

Low air pressure

E  2 No input signal from pressure switch or failure in air supply
to
(display E d2, E d3, E d4, E d5, E d6, E d7 or E d8) during program step 2, 3, 4, 5, 6, 7 or 8
E  8
Air flow during pre-purge E  P Air flow failure during pre-purge
Waiting for connection  0 BCU waiting for connection to controller
Invalid address  1 Invalid or incorrect address set on bus module
The bus module has received an incorrect configuration from the
Invalid configuration  2 controller
Invalid network name or no address allocated in the network
Invalid network name  3 name
Controller in STOP position  4 Controller in STOP position
Burner 1 flame simulation E A1 Burner 1 flame simulation while air valve open
No flame after safety time 1 E  A2 No flame during safety time 1 while air valve open
Flame failure during flame proving period 1 E  A3 Flame failure during flame proving period 1 while air valve open
Flame failure during burner 1 operation E  A4 Flame failure during burner 1 operation while air valve open
Burner 2 flame simulation E  A5 Burner 2 flame simulation while air valve open
No flame after safety time 2 E  A6 No flame during safety time 2 while air valve open
Flame failure during flame proving period 2 E  A7 Flame failure during flame proving period 2 while air valve open
Flame failure during burner 2 operation E  A8 Flame failure during burner 2 operation while air valve open

BCU 480 · Edition 11.19 55

Parameters

10 Parameters
Any changes to parameters will be saved to the parameter chip card.

10.1 Application parameters

Factory default
Name Parameter Value range Description settings
2 – 20 µA where
I004 = 0, 3 or 4,
Burner 1 flame signal FS1 switch-off Burner 1 flame signal switch-off threshold in µA 5 – 20 µA where
A001 2 – 20
threshold (depending on I004) I004 = 1, 5 or 6,
5 µA where
I004 = 2, 7 or 8
2 – 20 µA where
I004 = 0, 5 or 7,
Burner 2 flame signal FS2 switch-off Burner 2 flame signal switch-off threshold in µA 5 – 20 µA where
A002 2 – 20
threshold (depending on I004) I004 = 1, 3 or 8,
5 µA where
I004 = 2, 4 or 6
0 Off
Flame simulation check in standby position A003 0
1 On
0 Off
2 Burner 1 with UVS and burner 2 with UVS
High temperature operation A006 0
3 Continuous operation with ionization/UVC 1
6 Burner 1 with UVS and burner 2 with ionization
1 1 start-up attempt
Burner 1 start-up attempts A007 2 2 start-up attempts 1
3 3 start-up attempts
1 1 start-up attempt
Burner 2 start-up attempts A008 2 2 start-up attempts 1
3 3 start-up attempts

BCU 480 · Edition 11.19 56

Parameters

Factory default
Name Parameter Value range Description settings
0 Off
1 Burner 1
2 Burner 2
Restart A009 3 Burner 1 and burner 2 (pilot and main burners) 0
4 Max. 5 × in 15 min. for burner 1
5 Max. 5 × in 15 min. for burner 2
6 Max. 5 × in 15 min. for burner 1 and burner 2
Safety time during operation A019 0; 1; 2; 3, 4 Time in seconds 1
Over-run time tN A039 0 – 60 Time in seconds 0
0 Off; checking the positions for minimum/maximum
capacity
1 On; for approaching the positions for minimum/maximum
Running time selection A041 0
capacity
2 On; for approaching the position for maximum capacity
3 On; for approaching the position for minimum capacity
Running time in seconds (can only be selected if
Running time A042 0 – 250 250
I020 = 2 or 3)
0 Off
Over-run A043 2 Low fire; actuator feedback 0
3 Low fire; time-bound
0 Opens on external activation
1 Opens with gas stage 1
Air actuator control A048 0
2 Opens with gas stage 2
4 Opens with V4 burner 1
Air actuator can be activated externally on 0 Cannot be activated
A049 0
start-up 1 Can be activated externally
0 Cannot be activated
Air actuator in the event of fault A050 1
1 Can be activated externally
0 Off
1 Tightness test before start-up
Valve proving system A051 0
2 Tightness test after shut-down
3 Tightness test before start-up and after shut-down
0 V0
1 V1
2 V2
Relief valve (VPS) A052 2
3 V3
4 V4
5 V5

BCU 480 · Edition 11.19 57

Parameters

Factory default
Name Parameter Value range Description settings
Measurement time for Vp1 A056 3 – 3600 Time in seconds 3600
Valve opening time tL1 A059 2 – 25 Time in seconds 2
Proof of closure function test period A060 0 – 6000 Time in seconds 10
Minimum operating time tB A061 0 – 250 Time in seconds 0
Minimum pause time tMP A062 0 – 3600 Time in seconds 0
0 Unlimited
Operating time in Manual mode A067 1
1 5 minutes
0 Flame mode
Combustion mode A074 2 High temperature operation without ignition 0
3 High temperature operation without burner 1 start
0 Burner 1
1 Burner 1 with pilot gas
Burner application 2 Burner 1 and burner 2
A078 0
3 Burner 1 and burner 2 with pilot gas
4 Two-stage burner 1
5 Burner 1 and two-stage burner 2
0 With shut-down
Pilot burner A079 1 Controlled externally 1
2 To start
0 Off
Fieldbus communication A080 1 With address check 0
2 No address check
0 Off
K-SafetyLink A081 0
1 On
1 Via fail-safe bus (K-SafetyLink)
Safety interlocks (bus) A085 2 Via terminal 2
5 Via fail-safe bus (K-SafetyLink) and terminal
0 Off
1 Via fail-safe bus (K-SafetyLink)
Purge (bus) A087 2 Via terminal 2
3 Via non-fail-safe bus
4 Via fail-safe bus (K-SafetyLink) or terminal
0 Off
1 Via fail-safe bus (K-SafetyLink)
High temperature operation (bus) A088 2
2 Via terminal
5 Via fail-safe bus (K-SafetyLink) and terminal

BCU 480 · Edition 11.19 58

Parameters

Factory default
Name Parameter Value range Description settings
0 Off
1 Via fail-safe bus (K-SafetyLink)
LDS (bus) A089 2
2 Via terminal
5 Via fail-safe bus (K-SafetyLink) and terminal
Safety time 1 tSA1 A094 2 – 15 s Time in seconds 3
Flame proving period 1 tFS1 A095 0 – 25 s Time in seconds 2
Safety time 2 tSA2 A096 2 – 10 s Time in seconds 3
Flame proving period 2 tFS2 A097 0 – 25 s Time in seconds 2
0 No function
48 POC V1
49 POC V2
Function of sensor 1 A101 50 POC V3 0
51 POC V4
52 POC V5
53 TC
Function of sensor 2 A102 See A101 See A101 0
Function of sensor 3 A103 See A101 See A101 0

BCU 480 · Edition 11.19 59

Parameters

10.2 Interface parameters

Factory default
Name Parameter Value range Description settings
0
1 Ionization
2 UVS
3 UVC
Ionization control for burner 1 and UVS control for
4 burner 2
Ionization control for burner 1 and UVC control for
Flame control I004 5 burner 2 0
UVS control for burner 1 and ionization control for
6 burner 2
UVS control for burner 1 and UVC control for burner 2
7 UVC control for burner 1 and ionization control for
burner 2
8 UVC control for burner 1 and UVS control for burner 2

0 Off
Air actuator I020 2 IC 40 0
5 Air valve
0 Off
Function of terminal 64 I040* 2 V5 0
3 Bus output 1
0 Off
1 Ready signal
2 Air signal
4 Cooling air valve
Contact 80, 81/82 function I050* 6
5 Flue gas valve
6 Fault signal
7 Burner 1 operating signal
8 Burner 2 operating signal
0 Off
1 Ready signal
2 Air signal
4 Cooling air valve
Function of contact 90, 91/92 I051* 1
5 Flue gas valve
6 Fault signal
7 Burner 1 operating signal
8 Burner 2 operating signal

BCU 480 · Edition 11.19 60

Parameters

Factory default
Name Parameter Value range Description settings
0 Off
1 Ready signal
2 Air signal
4 Cooling air valve
Function of contact 95/96 I052* 7
5 Flue gas valve
6 Fault signal
7 Burner 1 operating signal
8 Burner 2 operating signal
0 Off
1 Ready signal
2 Air signal
4 Cooling air valve
Function of contact 95/97 I053* 8
5 Flue gas valve
6 Fault signal
7 Burner 1 operating signal
8 Burner 2 operating signal
0 Off
1 Ready signal
2 Air signal
4 Cooling air valve
Function of contact 85/86, 87 I054* 2
5 Flue gas valve
6 Fault signal
7 Burner 1 operating signal
8 Burner 2 operating signal
0 Off
4 Safety interlocks
5 Air
6 Cooling air
7 Air actuator R1
8 Air actuator R2
Function of input 1 I061* 9
9 Start 1
10 Start 2
11 Reset
12 Purge
13 LDS start-up conditions
14 High temperature operation
Function of input 2 I062* See I061 See I061 11

BCU 480 · Edition 11.19 61

Parameters

Factory default
Name Parameter Value range Description settings
Function of input 3 I063* See I061 See I061 12
Function of input 4 I064* See I061 See I061 5
Function of input 5 I065* See I061 See I061 10
Function of input 6 I066* See I061 See I061 14
Function of input 7 I067* See I061 See I061 0
Function of input 35 I068* See I061 See I061 4
0 Off
1 Sensor 1
2 Sensor 2
3 Sensor 3
4 Safety interlocks
5 Air
6 Cooling air
Function of input 36 I069* 0
7 Air actuator R1
8 Air actuator R2
9 Start 1
11 Reset
12 Purge
13 LDS start-up conditions
14 High temperature operation
Function of input 37 I070* See I069 See I069 0
Function of input 38 I071* See I069 See I069 0
Function of input 39 I072* See I061 See I061 13
Function of input 40 I073* See I061 See I061 7
Function of input 41 I074* See I061 See I061 8
* Interface parameters I040 to I099 are set at the factory and normally do not need to be adjusted.

BCU 480 · Edition 11.19 62

Parameters

10.3 Scanning the parameters (parameter A094) or during operation after the elapse
During operation, the four-digit 7-segment display of the safety time during operation (parameter A019).
shows the program step/status. In the case of UV control, this value can be increased,
In addition to the flame signal and the fault history, all should the burner to be monitored be influenced by
the parameters of the BCU can be scanned in numeri- other burners, for example.
cal order by repeatedly pressing the Reset/Information The adjustable range for the flame signal switch-off
button (for 1 s). threshold for burner 1 is dependent on the setting of
The parameter display is ended 60 seconds after the interface parameter I004 (Flame control):
last time the button is pressed or by switching off I004 = 0, 3 or 4
the BCU. (ionization control of burner 1): 2 – 20 µA,
I004 = 1, 5 or 6
The BCU indicates  when the mains switch has been
(control of burner 1 using UVS sensor): 5 – 20 µA,
switched off. The parameters cannot be scanned when
I004 = 2
the BCU is switched off or when a fault or warning is
(control of burner 1 using UVC sensor): 5 µA
displayed.

10.4 Flame control

The BCU is fitted with flame amplifiers which evaluate
whether an adequate flame signal is supplied by the
burner using a flame rod or UV sensor.
10.4.1 Burner 1 flame signal FS1 switch-off threshold
Parameter A001
The sensitivity at which the burner control unit still
detects a flame at burner 1 can be set using param-
eter A001.
As soon as the measured flame signal falls below the
set value (2 to 20 �A), the BCU performs a fault lock-
out during start-up after the elapse of safety time 1

BCU 480 · Edition 11.19 63

Parameters
10.4.2 Burner 2 flame signal FS2 switch-off threshold
Parameter A002
The sensitivity at which the burner control unit still
detects a flame at burner 2 can be set using param-
eter A002.
As soon as the measured flame signal falls below the
set value (2 to 20 �A), the BCU performs a fault lock-
out during start-up after the elapse of safety time 2
(parameter A096) or during operation after the elapse
of the safety time during operation (parameter A019).
In the case of UV control, this value can be increased,
should the burner to be monitored be influenced by
other burners, for example.
The adjustable range for the flame signal switch-off
threshold for burner 2 is dependent on the setting of
interface parameter I004 (Flame control):
I004 = 0, 5 or 7
(ionization control of burner 2): 2 – 20 µA,
I004 = 1, 3 or 8
(control of burner 2 using UVS sensor): 5 – 20 µA,
I004 = 2, 4 or 6
(control of burner 2 using UVC sensor): 5 µA

BCU 480 · Edition 11.19 64

Parameters
00 01 02 . . . 88
10.4.3 Flame simulation check in standby
Start 1 position lation check, it starts the flame simulation delay time tLV1
V1
Parameter A003 t (pilot burner) or tLV2 (main burner) for 25 s each. If the
tW
This defines the instant for the flame simulation check. extraneous signal disappears during this time, the pilot or
main burner can start. Otherwise, a fault lock-out occurs.
00 02 . . . 88 Flame simulation during tLV1:
Start 1
V1 E 01 flashes on the display.
t
Flame simulation check in standby position (parameter
Parameter A003 = 0: flame simulation check in standby A003 = 0):
position. The flame simulation check is conducted pro-
00 E 01 88
vided no start-up signal (start 1) is applied (during the L
so-called start-up position/standby). This allows fast 35
1 ϑ
start-up of the burner since there is no waiting time tW. 51
22
60 V1
The burner must have been switched off for at least 4 s 61 V2
before start-up in order for the flame simulation check 82 1
96
to be conducted correctly. tLV1 t

00 01 02 . . . 88 Flame simulation check on start-up (parameter A003 = 1):

Start 1
V1

tW t 00 01 E 01 88
L
1 ϑ
Parameter A003 = 1: flame simulation check on start- 51
22
00 simulation check is conducted
up. The flame 02 . . . 88 after ap- 60 V1
Start 1 61 V2
plying the start-up signal (start 1 or start 2)V1during the 96
waiting time tW. t t
tLV1
What is flame simulation?
Flame simulation means that an extraneous signal is The flame simulation check of the pilot burner is always
detected as a flame signal out of sequence. If the BCU active until valve V3 is enabled.
detects such an extraneous signal during the flame simu-
▼

BCU 480 · Edition 11.19 65

Parameters
Flame simulation during tLV2 (with permanent pilot
burner only):
E 05 flashes on the display.
Flame simulation check in standby position (parameter
A003 = 0):

00 E 05 88
L
35
1 ϑ1
1 ϑ2
51
22
23
60 V1
61 V2
62 V3
63 V4
96 1
97 2
82
tLV1 t

Flame simulation check on start-up (parameter

A003 = 1):

00 01 02 03 04 05 E 05 88
L
1 ϑ1
5 ϑ2
51
22 1
23 2
60 V1
61 V2
62 V3
63 V4
96
tLV1 tLV2 t

The flame simulation check of the main burner is always

active until valve V2 is enabled.

BCU 480 · Edition 11.19 66

Parameters
10.4.4 High temperature operation
FCU 500..H1
Parameter A006
M
BCU 480..D1
Operation of firing systems above 750°C. The BCU.. 5-8
HT STM µC
D1 and BCU..D2 have a fail-safe input with the func- 18
HT
tion “High temperature operation”. If firing systems are 6
operated above 750°C, the system is considered to be 22 23

an item of high temperature equipment (see EN 746-2). BCU 480..D1

Here, flame control must be in operation until the fur- µC

nace wall temperature has exceeded 750°C. HT

6
Below 750°C, the flame is monitored by conventional 22 23

means (UV sensor or flame rod). In High temperature

mode (> 750°C), the flame may be controlled via the
temperature using a safety temperature monitor (STM)
in order to increase the system’s availability. This means
that no incorrect flame signals, e.g. signals from a UV
sensor which interprets reflected UV radiation as extra- When the HT input is activated (terminal 6), the burner
neous signals, may lead to faults. control unit reverts to High temperature mode, i.e.: the
BCU operates without evaluation of the flame signal.
The safety function of the device’s internal flame con-
trol system is deactivated.
In High temperature mode, the gas valves are opened
and the burners are started as usual without monitor-
ing the presence of a flame.
▼

BCU 480 · Edition 11.19 67

Parameters
The precondition for this operating mode is that an Parameter A006 = 0
external flame supervision device ensures the pres- The High temperature mode function is switched off.
ence of the flame in a fail-safe manner indirectly via Flame control takes place dependent on the setting in
the temperature. For this purpose, we recommend a parameter I004 using a flame rod, a UVS sensor or a
safety temperature monitor with double thermocouple UVC sensor.
(DIN 3440). The flame must be monitored again by Parameter A006 = 2 (BCU..D1)
conventional means (UV sensor or flame rod) in the
08 01 02 03 04 06 07 08 88
event of sensor discontinuity or short-circuit, failure of L L1
the safety temperature monitor or power failure. 35
1 ϑ1
51
Only if the temperature at the furnace wall has ex- 6 HT
60 V1
ceeded 750°C may voltage be applied to the HT input 63 V4
22 1
(terminal 6) so as to activate High temperature mode. 5 ϑ2
61 V2
00 02 03 04 06 07 08 88 23 2
L L1 82
35 95 1
1 ϑ1 96 2
6 HT tSA2 tFS2 t
51 tZ tFS1
60 V1
63 V4 tW tSA1
22 1
5 ϑ2
61 V2 The BCU switches off burner 1 and burner 2 and re-
23 2
82 starts with flame simulation check (recommended in
95 1
96 2 the case of UV control with UVS).
tZ tFS1 tSA2 tFS2 t
▼
tSA1

If the temperature in the furnace chamber drops below

750°C, the HT input must be disconnected from the
electrical power supply and the furnace must then be
operated with flame control.
The BCU then responds, depending on setting:

BCU 480 · Edition 11.19 68

Parameters
Parameter A006 = 3 (BCU..D1) The BCU switches off burner 1 and restarts it with
flame simulation check. Burner 2 continues to operate
08 08 88
L L1 as long as no flame failure occurs.
35
1 ϑ1 If no flame signal is present when High temperature
51
6 HT mode is deactivated, the burner control unit performs a
60 V1
63 V4 fault lock-out, regardless of parameter A006.
22 1
5 ϑ2 Fault, pilot burner
61 V2
23 2
82 04 E 04 88
96 L L1
t 35
1 ϑ1
51
The burners remain in operation and the BCU performs 6 HT
60 V1
flame control again on both burners (recommended for 63 V4
22 1
ionization control or UV control with UVC). 5 ϑ2
61 V2
23 2
41
Parameter A006 = 6 (BCU..D2) 42
t
08 01 02 03 04 06 07 08 88
L L1 Fault, main burner
35
1 ϑ1
51 08 E 08 88
6 HT L L1
60 V1 35
63 V4 1 ϑ1
22 1 51
5 ϑ2 6 HT
61 V2 60 V1
23 2 63 V4
82 22 1
95 1 5 ϑ2
96 2 61 V2
t 23 2
tZ tFS1 tSA2 tFS2 82
96
tW tSA1 t

BCU 480 · Edition 11.19 69

Parameters

10.5 Behaviour during start-up If no flame is formed during the start-up, so that at the
end of the safety time tSA1 no flame signal is detected,
10.5.1 Burner 1 start-up attempts
this will result in a BCU safety shut-down with subse-
Parameter A007
quent fault lock-out. The fault message E 04 will flash
This parameter defines the maximum number of pos- in the BCU display depending on the burner operating
sible start-up attempts of burner 1. mode.
Taking into account national standards and require- Parameter A007 = 2, 3:
ments, it must be clarified whether multiple start-up 2 or 3 start-up attempts.
attempts are permitted.
00 02 01 02 E 04 88
In accordance with EN 746-2, a restart may be con- L L1
35
ducted only if the safety of the installation is not im- 1 ϑ
51
paired. 22
60 V1
Multiple start-up attempts are not permitted under 61 V2
62 V3
NFPA 86. If no flame forms during start-up, this must 82
96
result in a fault lock-out. t
tZ tZ
If no flame is detected during start-up, an immediate tSA1 tW tSA1
fault lock-out (A007 = 1) or up to two additional start-
up attempts (A007 = 2, 3) are performed depending on If no flame is formed during the start-up, so that at the
parameter A007. end of the safety time tSA1 no flame signal is detected,
the BCU closes the gas valves and repeats the start-up.
Parameter A007 = 1: 1 start-up attempt.
Each start-up attempt begins with the parameterized
00 02 E 04 8888 start-up behaviour.
L L1
35 If the safety time tSA1 elapses without a flame signal
1 ϑ
51 having been detected, even after the last parameterized
22
60 V1 start-up attempt, this will result in a BCU safety shut-
61 V2
62 V3 down with subsequent fault lock-out. The fault mes-
82
96 sage E 04 will flash in the BCU display depending on the
t
tZ burner operating mode.
t SA1

BCU 480 · Edition 11.19 70

Parameters
10.5.2 Burner 2 start-up attempts If no flame is formed during the start-up, so that at the
Parameter A008 end of the safety time tSA2 no flame signal is detected,
This parameter defines the maximum number of pos- this will result in a BCU safety shut-down with subse-
sible start-up attempts of burner 2. quent fault lock-out. The fault message E 04 will flash
in the BCU display depending on the burner operating
Taking into account national standards and require-
mode.
ments, it must be clarified whether multiple start-up
attempts are permitted. Parameter A007 = 2, 3: 2 or 3 start-up attempts.
In accordance with EN 746-2, a restart may be con- 00 02 03 04 06 05 06 05 06 E 06 88
L L1
ducted only if the safety of the installation is not im- 35
1 ϑ1
paired. 51
60 V1
Multiple start-up attempts are not permitted under 61 V4
22 1
NFPA 86. If no flame forms during start-up, this must 5 ϑ2
61 V2
result in a fault lock-out. 23 2
82
If no flame is detected during start-up, an immediate 96 1
97 2
fault lock-out (A008 = 1) or up to two additional start- tZ tFS1 t
tSA2 tW tSA2 tW tSA2
up attempts (A008 = 2, 3) are performed depending on tSA1
parameter A008.
If no flame is formed during the start-up, so that at the
Parameter A008 = 1: 1 start-up attempt.
end of the safety time tSA2 no flame signal is detected,
00 02 03 04 06 E 06 88 the BCU closes the gas valves and repeats the start-up.
L L1
35 Each start-up attempt begins with the parameterized
1 ϑ1
51 start-up behaviour.
60 V1
63 V4 If the safety time tSA2 elapses without a flame signal
22 1
5 ϑ2 having been detected, even after the last parameterized
61 V2
23 2 start-up attempt, this will result in a BCU safety shut-
82
96 1 down with subsequent fault lock-out. The fault mes-
97 2
t sage E 08 will flash in the BCU display depending on the
tZ tFS1 tSA2
tSA1 burner operating mode.

BCU 480 · Edition 11.19 71

Parameters
10.5.3 Burner application to start the burner. The burner is started with a limited
Parameter A078 ignition capacity using gas valve V3. After the elapse of
This parameter enables the BCU to be adjusted to vari- the safety time tSA1 (program step 02), valve V2 opens.
ous burner applications. In addition, an optional pilot Valve V3 limits the ignition capacity. After the elapse
gas valve (V3) can be parameterized via which the of the flame proving period tFS1 (program step 04), it is
burner is started with a defined ignition capacity. closed again.
Parameter A078 = 0: burner 1. Two valves (V1, V2) are For this application, it must be ensured that the flame
included for the burner. These are connected to the proving period (parameter A095) is set to a value ≥ 2 s.
valve outputs (terminals 60 and 61). Valves V1 and V2 V3
are opened in parallel to start the burner in order to re-
lease the gas supply to the burner.

V1 V2
V1 V2 60 61 62

BCU 46x
60 61 62
01 02 03
µC 04
BCU 46x 52 51
01 02 03 04 55
54 60 1
µC
52
51 53
61 2
55 60 1 58 47 48 56
62 3
54
53 61 2 22
58 47 48 56 62 3 96 1
22
96 1
tBP tSA1 tFS1 t
tBP tSA1 tFS1 t
▼
Parameter A078 = 1: burner 1 with pilot gas. Three
valves (V1, V2 and V3) are included for a burner with a
pilot gas valve. These are connected to the valve out-
puts (terminals 60, 61 and 62). Valves V1 and V3 open

BCU 480 · Edition 11.19 72

Parameters
Parameter A078 = 2: burner 1 and burner 2. Three V2 opens (terminal 61). Pilot gas valve V3 is closed
valves (V1, V2 and V4) are included for a modulating again after the elapse of the flame proving period tFS2
burner with a pilot burner. These are connected to the (program step 07).
valve outputs (terminals 60, 61 and 63). Valves V1 and For this application, it must be ensured that the flame
V4 open to start the pilot burner. Gas valve V2 releases proving period (A097) is set to a value ≥ 2 s.
the gas supply to the main burner.
V3

V1 V2

V1 V2
60 61 63 V4

BCU 480 60 61 62 63 V4
H1 02 03
µC
06 07 H8 08 BCU 480..C1F1
51
55
54
60 1 H1 02 03
µC 06 07 H8 08
53 61 2 52 51
55
56 62 3 54 60 1
53
63 4 61 2
58 47 48 56
22 1 62 3
23 2 63 4
96 2
22 1
23 2
tSA1 tFS1 tSA2 tFS2 tRF t 96 2

Parameter 78 = 3: burner 1 and burner 2 with pilot gas. tSA1 tFS1 tSA2 tFS2 tRF t
In this application, the burner has an additional pilot
gas valve V3. The valves are connected to the valve ▼
outputs (terminals 60, 61, 62 and 63). Valves V1 and V4
open to start the pilot burner. The burner is started with
a limited ignition capacity using gas valve V3. After the
elapse of the safety time tSA2 (program step 06), valve

BCU 480 · Edition 11.19 73

Parameters
Parameter A078 = 4: two-stage burner 1. Three valves Parameter 78 = 5: burner 1 and two-stage burner 2. In
(V1, V2 and V3) are included for a two-stage burner. this application, the burner has an additional pilot gas
These are connected to the valve outputs (terminals 60, valve V3. The valves are connected to the valve outputs
61 and 62). (terminals 60, 61, 62 and 63). Valves V1 and V4 open
to start the pilot burner. The burner is started with a
V3
limited ignition capacity using gas valve V3. Valve V2
(terminal 61) can be opened with the operating signal
(program step 08) in order to operate burner 2 at maxi-
mum capacity.
V1 V2
V3
60 61 62

BCU 46x

µC
01 02 03 0452
55 V1 V2
54 51
53
60 1
58 47 48 56
61 2 60 61 62 63 V4
62 3
22 BCU 480..C1F1
96 1
02 03 04
µC H 04 06 07 08
t
52
55
51
tBP tSA1 tFS1 54 60 1
53
61 2
58 47 48 56
Valves V1 and V3 open to start the burner. The burner 62 3
63 4
is started with a limited ignition capacity using gas 22 1
valve V3. After the flame proving period tFS1 has 23 2
elapsed, valve V2 opens to enable the 2nd gas stage. 96 2

tSA1 tFS1 tSA2 tFS2 t

BCU 480 · Edition 11.19 74

Parameters
10.5.4 Pilot burner Parameter A079 = 1: controlled externally.
Parameter A079 00 01 02 04 05 06 88
1
Burner 1 (pilot burner) is used to ignite burner 2 (main 1
burner). The start-up/operating properties of burner 1 2
2
can be set using parameter A079. t
tW1 tW2

Burner 1 is started and deactivated depending on start-

Parameter A079 = 0: with shut-down.
up signal 1. Burner 1 continues to operate even if the
00 02 04 06 07 08 88 main burner is active.
1
1 Burner 2 can only be started if burner 1 is in operation.
2
2
<1s
▼
t
tSA2

Burner 2 is started if burner 1 is in operation and start-

up signal 2 is active. As soon as safety time tSA2 has just
one second left to run, burner 1 is switched off regard-
less of start-up signal 1.
08 02 04 88
1
1
2
2

If start-up signal 2 is deactivated while burner 2 is in

operation and start-up signal 1 is active, burner 1 is re-
started. Burner 2 is deactivated as soon as burner 1 is
in operation.

BCU 480 · Edition 11.19 75

Parameters
Parameter A079 = 2: to start.
00 01 02 04 05 06 01 02 04 88
1
1
2
2

tW1 tW2 tW1 t

Burner 1 is started with start-up signal 1. Afterwards,

burner 2 is started. As soon as safety time tSA2 has just
one second left to run, burner 1 is deactivated regard-
less of the start-up signal. The start-up signal has no
effect on the burner start.
Burner 2 is deactivated if start-up signal 2 is deactivat-
ed during operation. Burner 1 can be restarted after it
has been shut down and after a successful flame simu-
lation check by activating start-up signal 1.

BCU 480 · Edition 11.19 76

Parameters
10.5.5 Safety time 1 tSA1 If the ϑ signal (terminal 1) drops out during safety
Parameter A094 time 1, the valves will not be switched off until the end
During safety time 1 tSA1, the flame (pilot flame) is ig- of safety time 1.
nited. It can be set to between 2 and 15 s. 10.5.6 Flame proving period 1 tFS1
Parameter A095
00 02 03 04 88
L L1
35 Flame proving period 1 (tFS1) can be parameterized
1 ϑ to enable the flame on burner 1 to stabilize after the
51
22 elapse of safety time 1. Only when the flame proving
60 V1
61 V2 period has elapsed will the next program steps be initi-
62 V3
82 ated by the BCU. The flame proving period can be set to
96
tZ t between 0 and 25 s.
tFS1
tSA1
00 02 03 04 88
L L1
Safety time 1 starts with the application of the ϑ sig- 35
1 ϑ
nal (terminal 1). The valves open at the start of safety 51
22
time 1. The fuel supply to burner 1 is released so that 60 V1
61 V2
a flame can form. If no flame is detected at the end of 62 V3
82
safety time 1, the valves are closed again. Depending 96
on parameter A007 (Burner 1 start-up attempts), the tZ tFS1 t

BCU reacts either with an immediate safety shut-down tSA1

with fault lock-out (A007 = 1) or with one or two ad-

ditional start-up attempts (A007 = 2 or 3). The BCU will
complete a maximum of three start-up attempts.
Safety time 1 must be determined on the basis of cur-
rent national standards and regulations. The burner
application and the burner capacity are the main cri-
teria for this.

BCU 480 · Edition 11.19 77

Parameters
10.5.7 Safety time 2 tSA2 If the ϑ1 signal (terminal 1) drops out during safety
Parameter A096 time 2, valve V4 will not be switched off until the end of
During safety time 2 tSA2, the flame on burner 2 (main safety time 2.
flame) is ignited. It can be set to between 2 and 10 s.
10.5.8 Flame proving period 2 tFS2
00 02 03 04 06 07 08 88 Parameter A097
L L1
35 Flame proving period 2 tFS2 can be parameterized
1 ϑ1
51 to enable the flame on burner 2 to stabilize after the
60 V1
63 V4 elapse of safety time 2. Only when the flame proving
22 1
5 ϑ2 period has elapsed will the next program steps be initi-
61 V2
23 2 ated by the BCU. The flame proving period can be set to
82
96 1 between 0 and 25 s.
97 2
tZ tFS1 tSA2 tFS2 t 00 02 03 04 06 07 08 88
L L1
tSA1 35
1 ϑ1
51
Safety time 2 starts with the application of the ϑ2 start- 60 V1
63 V4
up signal (terminal 5). Valve V2 opens at the start of 22 1
5 ϑ2
safety time 2. The fuel supply to burner 2 is released so 61 V2
23 2
that a flame can form. If no flame is detected at the end 82
96 1
of safety time 2, the valves are closed again. Depending 97 2
on parameter A008 (Burner 2 start-up attempts), the tZ tFS1 tSA2 tFS2 t

BCU reacts either with an immediate safety shut-down tSA1

with fault lock-out (A008 = 1) or with one or two ad-

ditional start-up attempts (A008 = 2 or 3). The BCU will
complete a maximum of three start-up attempts.
Safety time 2 must be determined on the basis of cur-
rent national standards and regulations. The burner
application and the burner capacity are the main cri-
teria for this.

BCU 480 · Edition 11.19 78

Parameters

10.6 Behaviour during operation Parameter A009 = 0: Off.

10.6.1 Restart
08 08 88
Parameter A009 L L1
35
Restart can be programmed for burners which occa- 1 ϑ1
51
sionally display unstable behaviour during operation. 60 V1
22 1
This parameter determines whether the BCU initiates 95 1
5 ϑ2
an immediate fault lock-out or an automatic restart 61 V2
23 2
after a safety shut-down during operation. Excessive 96 2
82
restarts, however, can be detected. t
tSB
Taking into account national standards and require-
ments, it must be clarified whether the restart func- A safety shut-down with subsequent fault lock-out
tion may be used. takes place in the event of flame failure during opera-
In accordance with EN 746-2, a restart may be con- tion.
ducted only if the safety of the installation is not im-
▼
paired.
The precondition for an automatic restart is that the
burner can restart (as intended in all operating phases).
In this case, it must be ensured that the program se-
quence started by the BCU matches the application.

BCU 480 · Edition 11.19 79

Parameters
Parameter A009 = 1: burner 1. The restart function is Parameter A009 = 2: burner 2.
active.
1x
1x 08 05 06 07 08 88
L L1
04 01 02 03 04 88 35
L L1 1 ϑ1
35 51
1 ϑ 60 V1
51 63 V4
22 22 1
60 V1 96 1
63 V4 5 ϑ2
82 61 V2
>2 s 96 1 23 2
>2 s 97 2
tFS t 82
tSB tZ
tSA2 tFS2 t
tW tSA tSB

tW2
If a safety shut-down occurs during operation (mini-
mum operating time of 2 s), the valves are closed and
If a safety shut-down occurs during operation (mini-
the operation signalling contact is opened within the
mum operating time of 2 s), valve V2 is closed and the
safety time during operation tSB. The burner control
operation signalling contact opened within the safety
unit then attempts to restart the burner once. If the
time during operation tSB. The burner control unit then
burner does not function, a safety shut-down with fault
attempts to restart burner 2 once. If burner 2 does not
lock-out occurs. The display blinks and shows the fault
function, a safety shut-down with fault lock-out occurs.
message.
The display blinks and shows the fault message.

Parameter A009 = 3: burner 1 and burner 2.

BCU 480 · Edition 11.19 80

Parameters
Parameter A009 = 4: max. 5 × in 15 min. for burner 1. If the start-up signal drops out before the start of op-
The restart function is active and is also monitored for eration/controller enable, e.g. during pre-purge, the
excessive restarts. burner control unit reverts directly to the start-up posi-
In certain conditions, it is possible that the restart func- tion (standby) and the burner is not ignited.
tion is repeated continuously without a safety shut- The minimum operating time can be cancelled by
down with subsequent fault lock-out being performed. switching off the BCU or if a safety shut-down occurs.
The BCU has a safety shut-down with subsequent fault
lock-out option if more than 5 restarts are performed
within a period of 15 minutes.
Taking into account national standards and require-
ments, it must be clarified whether the option may be
used.
Parameter A009 = 5: max. 5 × in 15 min. for burner 2.
Parameter A009 = 6: max. 5 × in 15 min. for burner 1
and burner 2.

10.6.2 Minimum operating time tB

Parameter A061
A minimum operating time (0 to 250 s) may be defined
to ensure that the heating equipment operates stably.
If the minimum operating time is active, burner opera-
tion will be maintained until the set time has elapsed
even if the start-up signal fails.
The minimum operating time starts as soon as the pro-
gram step for operation/controller enable (display 08)
has been reached.

BCU 480 · Edition 11.19 81

Parameters

10.7 Safety limits

Parameters A016 and A019 can be used to adjust the
safety limits (low air pressure protection and safety
time during operation) to the system requirements.
10.7.1 Safety time during operation
Parameter A019
Parameter A019 = 0; 1; 2; 3; 4: Time in seconds
The safety time during operation is the time that the
BCU needs to stop the fuel supply after a flame failure
during operation or an interruption at the safety current
inputs (terminals 36, 37 and 38). The safety time can
be set to between 0 and 4 s in steps of 1 s. Prolonging
the safety time during operation increases the instal-
lation availability in the case of brief-duration signal
fades (e.g. fades of the flame signal).
The requirements of national standards and regula-
tions must be satisfied.
In accordance with EN 298, the maximum reaction
time to a flame failure must not exceed 1 s. Specific ap-
plication standards may permit other values.
Under EN 746-2, the safety time of the installation dur-
ing operation (total closing time) must not exceed 3 s.
Under NFPA 86, section 8.10.3*, the maximum flame
failure response time shall be ≤ 4 s.

BCU 480 · Edition 11.19 82

Parameters

10.8 Air control the BCU will initiate the next program step. Approach-
ing the position for maximum capacity is signalled and
10.8.1 Running time selection
monitored.
Parameter A041
Parameter A041 = 0: Off; checking the positions for
minimum/maximum capacity. A signal that the posi-
tions for minimum and maximum capacity have been
reached is returned and monitored with a timeout time
of max. 250 s. When the position has been reached, the
BCU will initiate the next program step.
Parameter A041 = 1: On; for approaching the positions
for minimum/maximum capacity. The running time
set using parameter A042 is activated for approaching
these positions, see page 84 (Running time). After
this time has elapsed, the BCU will initiate the next pro-
gram step.
Parameter A041 = 2: On; for approaching the position
for maximum capacity. The running time set using pa-
rameter A042 is activated for approaching the position
for maximum capacity, see page 84 (Running time).
After this time has elapsed, the BCU will initiate the next
program step. Approaching the position for minimum
capacity is signalled and monitored.
Parameter A041 = 3: On; for approaching the position
for minimum capacity. No signal is returned that the
position for minimum capacity has been reached. The
running time set using parameter A042 is activated for
approaching the position for minimum capacity, see
page 84 (Running time). After this time has elapsed,

BCU 480 · Edition 11.19 83

Parameters
10.8.2 Running time 10.8.3 Over-run
Parameter A042 Parameter A043
This parameter can be used to adjust the behaviour in The over-run (tKN) supports applications with a pneu-
the case of slow opening and closing air valves. The matic air/gas ratio control system and On/Off control.
running time starts when the air actuator is switched Using the over-run function reduces the O2 content in
off. A restart of the burner after a controlled shut-down, the furnace atmosphere.
a start-up attempt, restart, cooling or purging is de-
A8 00 88
layed until the end of the running time. After the run- L L1
35
ning time has elapsed, the burner is started if the start- 1 ϑ1
5 ϑ2
ϑ2
up signal (ϑ) is applied. 51
22
The time should be adjusted such that the system can 60 V1
61 V2
be set to ignition position, i.e. that the air actuator is 4 A
65
closed before a start-up is initiated. 82
96 1
97 2
tKN t

Parameter A043 = 0: Off. No over-run is performed.

The gas circuit is closed immediately owing to a quick
closing gas valve in the case of On/Off control. The air
circuit is closed more slowly. The air flowing in during
this time increases the O2 content in the combustion
chamber.
Parameter A043 = 1: post-ventilation (with BCU/LM..F1
only). The gas supply will be closed. Air continues to be
supplied for the programmed duration depending on
parameter A039.

BCU 480 · Edition 11.19 84

Parameters
Parameter A043 = 2: low fire over-run until actuator control is still operational. It must be ensured that no
feedback. The air actuator is closed with a deactivated excess gas occurs.
start-up signal in the event of a controlled shut-down.
The gas valves remain open for the programmed dura-
tion depending on parameter A039 (Over-run time) or
until the air actuator is closed. The gas valves are closed
immediately in the event of a flame failure. A flame fail-
ure during the over-run does not result in a fault lock-
out.
Parameter A043 = 3: low fire over-run, time-bound.
V1 V2

VAS VAG V4
VAS 1

BCU 480..F3

µC 60
61
63

23
65 22

VR..L

The burners are initially powered down to low-fire rate

and remain in operation for the programmed duration
depending on parameter A039 (Over-run time). Flame

BCU 480 · Edition 11.19 85

Parameters
10.8.4 Air actuator control (Two-stage-controlled main burner with permanent
Parameter A048 pilot burner). In this case, activation of the air actuator
In cyclic operation, parameters A048 and A049 on during burner start via the input at terminal 4 must be
BCU..F1 and F3 determine the behaviour of the air ac- prevented.
tuator during burner start and burner operation. External control allows switchover between low fire and
The air actuator can be activated externally via the in- high fire during operation.
put at terminal 4 for cooling the burner in the start-up Parameter A048 = 1: opens with gas stage 1 (start fuel
position (standby). This function is not available during flow rate).
burner start-up and during operation.
00 A0 00 A0 00 02 03 04 A6 A7 A8 88
Parameter A048 = 0: opens on external activation. L1
35
1 ϑ1
00 A0 02 03 04 06 07 A8 88 5 ϑ2
L1 51
35 22 1
1 ϑ1 23 2
5 ϑ2 60 V1
51 62 V2
63 V3
22 1 64 V4
23 2 4 A
60 V1 65 ∨ 66
M

61 V2
62 V3 96 1
63 V4 97 2

4 A M
82
65 ∨ 66 t
22 1 tZ tFS1 tSA2 tFS2
23 2
tSA1
82
tZ tSA2 t
tA042 tFS1 tFS2 The air actuator opens at the same time as safety
tSA1 time tSA2 begins and the main burner starts.

This setting together with parameter A049 = 0, see ▼

page 88 (Air actuator can be activated externally on
start-up), is required for burners on which the air/gas
ratio is controlled by a pneumatic air/gas ratio control
system and which need to be started at low-fire rate,
e.g. on two-stage-controlled burners, see page 9

BCU 480 · Edition 11.19 86

Parameters
Parameter A048 = 2: opens with gas stage 2 (operating Parameter 48 = 1: opens with V4 burner 1.
fuel flow rate). 00 A0 00 A0 00 A2 A3 A4 A6 A7 A8 88
L1
00 A0 00 A0 00 02 03 04 06 07 A8 88 35
L1 1 ϑ1
35 5 ϑ2
1 ϑ1 51
5 ϑ2 22 1
51 23 2
22 1 60 V1
23 2 61 V2
60 V1 62 V3
61 V2 63 V4
62 V3 4 A M

63 V4 65 ∨ 66
4 A 96 1
65 ∨ 66
M
97 2
96 1 82
97 2
tZ tSA2 t
82 tFS1 tFS2
t tSA1
tZ tFS1 tSA2 tFS2
tSA1 The air valve opens with the start fuel flow rate. The air
valve can be activated externally via the input at ter-
This setting is required in the case of two-stage main
minal 4 for cooling the burner in the start-up position/
burners which are switched ON/OFF via the ϑ2 input.
standby.
The air valve opens simultaneously with the operating
signal for the main burner. The air valve can be acti-
vated externally via the input at terminal 4 for cooling
the burner in the start-up position/standby. This func-
tion is not available during burner start-up and during
operation.

BCU 480 · Edition 11.19 87

Parameters
10.8.5 Air actuator can be activated externally on 00 A000 A000 A2 A3 A4 A6 A7 A8 88
start-up L1
35
Parameter A049 1 ϑ1
51
60 V1
Parameter A049 = 0: cannot be activated. 22 1
96 1
00 A000 A000 02 03 04 06 07 A8 88 5 ϑ2
L1 61 V2
35 23 2
1 ϑ1
51 97 2
60 V1 4 A M

22 1 65 ∨ 66
96 1 82
5 ϑ2 tZ tSA2 t
61 V2 tFS1 tFS2
23 2 tSA1
97 2
4 A
65 ∨ 66
M
The air actuator can be activated externally via the input
82
at terminal 4 during start-up. Parameter A048 must be
tZ tFS1 tSA2 t
tFS2 set to 0 for this purpose, see also page 86 (Air actua-
tSA1
tor control).
During start-up, the air actuator remains closed. The air 10.8.6 Air actuator in the event of fault
actuator cannot be activated externally. Parameter A050
Parameter A049 = 1: can be activated externally. This parameter decides whether the air actuator can
be activated externally via the input at terminal 4 in the
event of a fault lock-out.
Parameter A050 = 0: cannot be activated. The air ac-
tuator remains closed in the event of a fault lock-out. It
cannot be activated externally via terminal 4.
Parameter A050 = 1: can be activated externally. The
air actuator can be activated externally via the input at
terminal 4 during a fault, e.g. for cooling.

BCU 480 · Edition 11.19 88

Parameters
10.8.7 Combustion mode Parameter A074 = 3: high temperature operation with-
Parameter A074 out burner 1 start.
The type of combustion in which the ignition takes
06 07 08
place can be set using parameter A074. 6 HT
1 ϑ1
Parameter A074 = 0: Flame mode.
5 ϑ2
88 51
00 02 03 04 06 07 08
L L1 96 1
6 HT 97 2
35
1 ϑ1 60 1
51 61 2
60 V1 63 4
63 V4
22 1 65
5 ϑ2 36 PZL
61 V2
23 2
82
tSA2 tFS2
t
96 1
97 2
tZ tFS1 tSA2 tFS2 t When connected to pilot and main burners, the
tSA1 BCU 480 can be parameterized so that the main burner
is started automatically in HT mode. The pilot burner’s
The burner is always started with ignition in Flame
start-up process is bypassed. The start-up signals for
mode and in High temperature mode. Flame control is
burner 1 and burner 2 must be active.
provided in High temperature mode by the high tem-
perature monitoring system.

BCU 480 · Edition 11.19 89

Parameters

10.9 Valve check V3

10.9.1 Valve proving system

Parameter A051 PZH
Parameter A051 is used to define whether and at what
time in the BCU program sequence the valve check is V1 Vp1 V2
activated. The tightness of the gas solenoid valves and
pu/2
the pipework between the valves are checked (tightness 38 60 61 62 63 V4
test).
Parameter BCU
A052480..C1F1
= 2: V2. The valve on terminal 61 acts
Parameter A051 = 0: Off. No valve check is activated.
as the relief valve.
µC
Parameter A051 = 1: tightness test before start-up.
Parameter A052 = 3: V3. The
52
55
valve on terminal 62 acts
Parameter A051 = 2: tightness test after shut-down. as the relief valve. 54
53
With this setting, a tightness test is also performed af-
Parameter58A052 47 = 4:
48 V4. The
56 valve on terminal 63 acts
ter a fault is reset and after mains on.
as the relief valve.
Parameter A051 = 3: tightness test before start-up and
Parameter A052 = 5: V5. The valve on terminal 64 acts
after shut-down.
as the relief valve.
An additional bypass valve must be installed in gas sec-
tions with an air/gas ratio control. This valve allows the
closed air/gas ratio control to be bypassed during the
tightness test.
10.9.2 Relief valve (VPS)
Parameter A052
One of the valves connected to terminal 61, 62, 63
or 64 can be selected to discharge the test volume dur-
ing a tightness test.

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Parameters
10.9.3 Measurement time for Vp1 maximum flow rate, the opening time of the bypass
Parameter A056 valves may be longer than the 3 s permitted by the
The required measurement time must be determined standard (EN 1643:2000).
according to the requirements of the appropriate appli-
cation standards, e.g. EN 1643.

V1 V2
PZ

Vp1

60 61
38
pu/2
ϑ 1
P
2
The required
3
measurement
µC time for the tightness test
>750°
of Vp1 can be set using parameter A056.
TC It is adjustable
BCU 56x..C1
from 3 to 3600 s.
See also page 36 (Measurement time tM).
10.9.4 Valve opening time tL1
Parameter A059
This parameter is used to define the opening time for
the valves (2 to 25 s) which are opened to fill or dis-
charge the test volume between the gas valves. If the
preset opening time tL = 3 s is inadequate (e.g. if slow
opening valves are used) to fill the test volume or re-
duce the pressure between the valves, bypass valves
can be used instead of the main valves.
On condition that the gas volume which flows into the
combustion chamber is no larger than 0.083% of the

BCU 480 · Edition 11.19 91

Parameters

10.10 Behaviour during start-up 10.11.1 Operating time in Manual mode

Parameter A067
10.10.1 Minimum pause time tMP
Parameter A062 Parameter A067 determines when Manual mode is ter-
minated.
A minimum pause time tMP (0 to 3600 s) can be defined
to achieve stable operation of the burners. If the over- Parameter A067 = 0: Manual mode is not limited in time.
run time set using parameter A039 has elapsed and no If this function has been selected, operation of the
start-up signal is received at terminal 1 and terminal 5 burner may be continued manually in the event of fail-
(burner shut down), a restart and cooling are prevented ure of the control system or the bus activation.
for the duration of the minimum pause time tMP. Parameter A067 = 1: the BCU will terminate Manual
If a signal is applied to terminal 1 (burner start-up) or mode 5 minutes after the last time the button is
terminal 2 (cooling) during the minimum pause time, pressed. It then moves abruptly back to the start-up
status display Delay  H0 will appear. position (standby).
If the unit is switched off or a power failure occurs,
10.11 Manual mode Manual mode on the BCU will be terminated regardless
If the Reset/Information button is pressed for 2 s dur- of parameter A067.
ing switch-on, the BCU reverts to Manual mode. Two
dots blink on the display. The BCU is now operating in
Manual mode independently of the status of the in-
puts for start-up signal (terminals 1 and 5), controlled
air flow (terminal 4) and remote reset (terminal 2). The
functions of the safety-relevant inputs such as control-
ler enable/emergency stop (terminal 35) are retained.
The manual start-up of the BCU can be initiated in
Manual mode by pressing the Reset/Information but-
ton. Each time the button is pressed again, the BCU
moves to the next step of the program sequence and
stops there, for example for adjusting an actuator or the
gas/air mixture.

BCU 480 · Edition 11.19 92

Parameters

10.12 Sensors Terminal 37 is assigned a sensor function using param-

A sensor for the pressure switch signal for the tightness eter A102.
test or a POC switch can be connected to each of the The value ranges and descriptions for the parameter are
inputs at terminals 36, 37 or 38, see also page 106 identical to parameter A101, see page 93 (Function
(Function of input 36). of sensor 1).
Parameter A101, A102 or A103 is used to define the 10.12.3 Function of sensor 3
sensor function (the sensor type and the program sta- Parameter A103
tus at which the sensor signal is evaluated by the BCU). Terminal 38 is assigned a sensor function using param-
Multiple sensors/POC switches may be used in paral- eter A103.
lel for the same function if two or three inputs are as-
The value ranges and descriptions for the parameter are
signed the same sensor function.
identical to parameter A101, see page 93 (Function
10.12.1 Function of sensor 1 of sensor 1).
Parameter A101
This parameter assigns a sensor function to terminal 36.
Parameter A101 = 48: proof of closure function V1. The
closed position of valve V1 Is monitored by the POC.
Parameter A101 = 49: proof of closure function V2. The
closed position of valve V2 Is monitored by the POC.
Parameter A101 = 50: proof of closure function V3. The
closed position of valve V3 Is monitored by the POC.
Parameter A101 = 51: proof of closure function V4. The
closed position of valve V4 Is monitored by the POC.
Parameter A101 = 52: proof of closure function V5. The
closed position of valve V5 Is monitored by the POC.
Parameter A101 = 53: tightness test. The pressure
switch signal for the tightness test is evaluated.
10.12.2 Function of sensor 2
Parameter A102

BCU 480 · Edition 11.19 93

Parameters
10.12.4 Proof of closure function test period
Parameter A060
Parameter A060 = 0 to 6000 s: testing time for the
closed position of one of the gas valves V1, V2, V3, V4
or V5.
When the start-up signal is received at terminal 1, the
BCU checks that one of the gas valves (V1 to V5) is in
its closed position using the POC switch. If a signal is
not received from the POC switch at terminal 36, 37
or 38, depending on parameter A101, A102 or A103,
after the set testing time (gas valve is closed), the BCU
performs a fault lock-out with fault message “E c1”.
As soon as the BCU has opened the gas valve, it que-
ries the open position of the valve via the POC switch.
If a signal is still being received from the POC switch at
terminal 36, 37 or 38 after the set testing time, the BCU
performs a fault lock-out with fault message “E c8”.

BCU 480 · Edition 11.19 94

Parameters

10.13 Communication
10.13.1 Fieldbus communication
Parameter A080
Fieldbus communication can be enabled using param-
eter A080 when bus module BCM 400 is connected.
A device name/network name must be entered in the
automation system/BCSoft for the unique identifica-
tion of the control unit (BCU/FCU) in the fieldbus sys- Code switch setting: upper switch (S1) = 102 (hundreds), cen-
tem. tre switch (S2) = 101 (tens), lower switch (S3 = 10 0 (ones)

Parameter 80 = 0: Off. Fieldbus communication is disa-

Parameter 80 = 2: no address check. The device name/
bled. Parameterization access using BCSoft via Ether-
network name can be selected as specified by the auto-
net is not possible.
mation system.
Parameter 80 = 1: with address check. The device
name/network name on delivery for the BCU 480 10.13.2 K-SafetyLink
is “not-assigned-bcu-480-xxx”. The expression “not- Parameter A081
assigned-” must be deleted or may be replaced with an In furnace control systems, consisting of FCU 50x and
individual name. The sequence xxx must be identical to BCU 480, the SafetyLink communications protocol
the address set on the BCM 400 using the code switch- is used to transfer safety-critical signals between the
es (xxx = address in the range 001 to FEF). FCU and BCU. The data transfer can be enabled using
parameter A081.
Parameter A081 = 0: Off. No data exchange takes place
via K-SafetyLink.
Parameter A082 = 1: On. Data exchange via K-Safe-
tyLink is enabled. The FCU must support this function.

BCU 480 · Edition 11.19 95

Parameters
10.13.3 Safety interlocks (bus) 10.13.6 LDS (bus)
Parameter A085 Parameter A088
This parameter defines the interface through which the This parameter defines the interface through which the
signal from the safety interlocks is received. LDS signal (limits during start-up) is received.
Parameter A085 = 1: via fail-safe bus Parameter A088 = 0: Off
Parameter A085 = 2: via terminal Parameter A088 = 1: via fail-safe bus
Parameter A085 = 5: via fail-safe bus and terminal Parameter A088 = 2: via terminal
10.13.4 Purge (bus) Parameter A088 = 5: via fail-safe bus and terminal
Parameter A087
This parameter defines the interface through which the
signal for purging is received.
Parameter A087 = 0: Off
Parameter A087 = 1: via fail-safe bus
Parameter A087 = 2: via terminal
Parameter A087 = 3: via non-fail-safe bus
Parameter A087 = 4: via fail-safe bus or terminal
10.13.5 High temperature operation (bus)
Parameter A088
This parameter defines the interface through which the
signal for High temperature mode is received.
Parameter A088 = 0: Off
Parameter A088 = 1: via fail-safe bus
Parameter A088 = 2: via terminal
Parameter A088 = 5: via fail-safe bus and terminal

BCU 480 · Edition 11.19 96

Parameters

10.14 Interface parameters er 2 flame control is performed with a UV sensor for
Interface parameters I040 to I099 are set at the fac- continuous operation (UVC).
tory and normally do not need to be adjusted. Chang- Parameter 04 = 7: burner 1 flame control is performed
ing the default settings of the interface parameters with a UV sensor for continuous operation (UVC), burn-
will change the functions of the inputs at terminals 1 er 2 flame control is performed with a flame rod.
to 41 and terminals 85 to 90, see also from page 19 Parameter 04 = 8: burner 1 flame control is performed
(Connection diagram). with a UV sensor for continuous operation (UVC), burn-
10.14.1 Flame control er 2 flame control is performed with a UV sensor for
Parameter I004 intermittent operation (UVS).

Parameter I004 = 0: flame control is performed with a Flame control using UV sensors
flame rod. For intermittent operation, the operating state of the
Parameter I004 = 1: flame control is performed with a complete system is limited to 24 h pursuant to EN 298.
UV sensor for intermittent operation (UVS). To meet the requirement for intermittent operation, the
burner is shut down and restarted automatically after a
Parameter 04 = 2: flame control is performed with a UV
continuous operating time of 24 hours if it is not oper-
sensor for continuous operation (UVC).
ated in compliance with the standard. The restart does
Parameter 04 = 3: burner 1 flame control is performed not meet the requirements of EN 298 for UV sensor
with a flame rod, burner 2 flame control is performed continuous operation because the required self-test (at
with a UV sensor for intermittent operation (UVS). least once per hour) is not performed while the burner
Parameter 04 = 4: burner 1 flame control is performed is operating. This shut-down and subsequent restart
with a flame rod, burner 2 flame control is performed are performed in the same way as a normal controlled
with a UV sensor for continuous operation (UVC). shut-down. Depending on the parameterization, the
Parameter 04 = 5: burner 1 flame control is performed burner is started with or without pre-purge. This pro-
with a UV sensor for intermittent operation (UVS), burn- cess is controlled independently by the BCU and there-
er 2 flame control is performed with a flame rod. fore it must be checked whether the industrial process
Parameter 04 = 6: burner 1 flame control is performed permits the pause in heat supply it creates.
with a UV sensor for intermittent operation (UVS), burn- ▼

BCU 480 · Edition 11.19 97

Parameters
The reaction times of the BCU and UV sensor for con-
tinuous operation are coordinated so that the set safety
time during operation (parameter A019) is not extend-
ed.

BCU 480 · Edition 11.19 98

 Parameters
10.14.2 Air actuator checks whether the position for maximum capacity has
Parameter I020 been reached. Terminal 40 checks the position for igni-
Parameter I020 = 2: IC 40. To ensure that the actua- tion capacity. If the position is not reached within the
tor IC 40 can be operated on the BCU..F1, parameter timeout time of 250 s, a safety shut-down of the BCU
I020 = 2 (capacity control) must be set. The operating will be performed. A fault message (E A , E A or E A  ) will
0 41 82 81 80 85 86 87 92 91 90 95 96 97 be displayed, see page 53 (Fault signalling).
mode of actuator IC 40 may be parameterized to 11
or 27. If a controller enable is active, the control system is
enabled for operation via the outputs at terminals 65
and 66.

0°➔90°
BCU..F1
N1 N1
90°
N1 ▼
L N L N
36 58 28 37 59 29 38 40 41 56 26 64 65 66 67

mA

22 21 20 19 18 16 15 14 12 11 10 8 7 5 4 2 1

A AC
D DC

IC 40

M
R..

PE

The positions for maximum capacity and ignition

capacity can be set using the actuator. Terminal 41

BCU 480 · Edition 11.19 99

Parameters
Operating mode 11 Operating mode 27
Operating mode 11 allows cyclic operation (ON/OFF During the controller enable procedure, the actuator
and OFF/Low/High/OFF). IC 40 can be adjusted infinitely between the positions
The actuator IC moves to the “High fire” position during for maximum and minimum capacity using its ana-
the controller enable procedure. 0There is no timeout logue input (terminals 18 and 19). There is no timeout
active in this case. active in this case.

t1 t2 t3 t4 t5 t6 t1 t2 t3 t4 t5 t6

Purge Purge

High 0–20
fire mA

Ignition Ignition
Closed Closed
t [s] t [s]
DI 1 DI 1
DI 2 DI 2
t [s] t [s]

BCU IC 40 (operating mode 11) BCU IC 40 (operating mode 27)
Signal at Signal at
terminal terminal Position Butterfly valve position
Position Butterfly valve position
65 66
65 66
OFF OFF Closed Closed
OFF OFF Closed Closed
ON OFF Ignition Minimum/Ignition capacity
ON OFF Ignition Minimum/Ignition capacity
Any position between minimum and
ON ON High-fire rate High-fire rate ON ON 0 – 20 mA maximum capacity
OFF ON Purge Maximum capacity OFF ON Purge Maximum capacity

BCU 480 · Edition 11.19 100

Parameters
Fault Parameter I020 = 5: air valve. The positions for maxi-
In the event of a fault, there will be no signal at ter- mum capacity and ignition capacity can be set using
minals 65 and 66 so that the actuator moves to the the air valve. If the air valve is closed, the ignition capac-
closed position. When approaching the closed posi- ity is reached, if it is open, the maximum capacity is
tion, no timeout of 250 s is active since no feedback reached.
input is checked. This may result in a situation where V1 V2
the program is continued in the case of a request for
the closed position, without the butterfly valve being VAS VAG
VAS 1
closed. The outputs at terminals 64 (controller enable)
and 67 (closed position) on the BCU are non-functional V4

and are not activated.

BCU 480/LM..F3
Manual mode 60

S
UV
61
µC 63
In Manual mode, no external controller is enabled. The 22
23
actuator can be moved to the positions for maximum
capacity or ignition capacity by the user. 3-point step 10
VR..L
operation is not possible. No timeout is active when ap-
proaching these positions.

Parameter A042 (Running time) can be used to adjust

the behaviour in the case of slow opening and closing
air valves so that the system can be set to ignition posi-
tion before a start-up is initiated, see page 84 (Run-
ning time). Parameter A041 (Running time selection)
must be set to 1 to adjust this behaviour.

BCU 480 · Edition 11.19 101

Parameters
10.14.3 Function of terminal 64
Parameter I040
Terminal 64 can be assigned a function using param-
eter I040 depending on the power module LM..F1 or
LM..F3. Alternatively, the output can be actuated using
a bus system.
Parameter I040 = 0: Off. The output has no function.
Parameter I040 = 2: valve V5. Terminal 64 can be used
to activate a fifth valve. This option can only be selected
if power module LM..F3 is used.
Parameter I040 = 3: bus output 1. The output at termi-
nal 64 can be actuated using a bus system.

BCU 480 · Edition 11.19 102

Parameters

10.15 Functions of contacts 80 to 97 10.15.2 Function of contact 90, 91/92

Contacts 80 to 97 are floating contacts. They can be Parameter I051
parameterized for various signalling functions. The For a description and the parameter values, see Con-
contacts between the relevant terminals close depend- tact 80, 81/82 function.
ing on the set function. 10.15.3 Function of contact 95/96
10.15.1 Contact 80, 81/82 function Parameter I052
Parameter I050 For a description and the parameter values, see Con-
Parameter I050 = 0: Off. The contact will not be closed. tact 80, 81/82 function.
It has no function 10.15.4 Function of contact 95/97
Parameter I050 = 1: ready signal. The contact is closed Parameter I053
if the BCU is ready (switched on) and there is no fault For a description and the parameter values, see Con-
signal. tact 80, 81/82 function.
Parameter I050 = 2: air signal. The air signal is activated
10.15.5 Function of contact 85/86, 87
as soon as a connected air actuator has reached or ex-
Parameter I054
ceeded its High position (max. position).
For a description and the parameter values, see Con-
Parameter I050 = 3: purge signal. The contact is closed
tact 80, 81/82 function.
while purging is active.
Parameter I050 = 4: cooling air valve. The contact is
closed if the cooling air valve is to be actuated.
Parameter I050 = 6: fault signal. The contact is closed if
a fault lock-out is active.
Parameter I050 = 7: burner 1 operating signal. The con-
tact is closed if burner 1 is in operation.
Parameter I050 = 8: burner 2 operating signal. The con-
tact is closed if burner 2 is in operation.

BCU 480 · Edition 11.19 103

Parameters

10.16 Functions of inputs at terminals 1 to 7 signal to actuate the cooling air actuator through the
and 35 to 41 input.
Parameter I061 = 7: air actuator R1. The BCU receives
The BCU has multiple physical and logical interfaces
the feedback signal for the ignition position from actua-
to receive its input signals and set output signals. Pa-
tor IC 40 through the input.
rameters I061 to I074 are used to define which input
Parameter I061 = 8: air actuator R2. The BCU receives
signals can be received at the various terminals (1 to 7
the feedback signal for the High position from actuator
and 35 to 41).
IC 40 through the input.
Sensors (pressure switches for the tightness test and Parameter I061 = 9: start 1. The BCU receives the start-
POC switches) can be connected to inputs 36, 37 up signal for the pilot burner (start 1) through the input.
and 38 depending on the parameter setting. Parameter I061 = 10: start 2. The BCU receives the start-
BCU..E0 up signal for the main burner (start 2) through the input.
Input 35 is reserved for the safety interlock function. All Parameter I061 = 11: reset. The BCU receives the signal
other inputs can also be parameterized for the safety for a remote reset through the input.
interlock function (I061 = 4). Parameter I061 = 12: purge. The BCU receives the
purge signal through the input.
10.16.1 Function of input 1
Parameter I061 Parameter I061 = 13: LDS. The BCU does not perform
a burner start-up, restart or start-up attempt until the
To define the input signal for terminal 1.
central actuator is in ignition position, see the applica-
Parameter I061 = 0: Off. The input has no function. tion example on page 11 (Modulating control with
Parameter I061 = 4: safety interlocks. The “safety inter- defined ignition position). To ensure that the burn-
locks” signal can be applied via the input and/or Safe- ers only start with the start fuel flow rate, the higher-
tyLink. No start-up is commenced if there is no signal at level control system sends a signal to start the burner
the input. If the signal drops out during operation, the through the terminal to the BCU.
gas valves are closed immediately (< 1 s).
▼
Parameter I061 = 5: air. The BCU receives the signal for
controlled air flow or for external air actuator control
through the input.
Parameter I061 = 6: cooling air. The BCU receives the

BCU 480 · Edition 11.19 104

Parameters
Parameter I061 = 14: high temperature operation. This 10.16.5 Function of input 5
input is used to signal to the burner control unit that the Parameter I065
furnace system is in High temperature mode (HT). The To define the input signal for terminal 5.
burner control unit switches to High temperature mode
For parameter values and descriptions, see page 104
when the HT input is activated. It operates without eval-
(Function of input 1).
uating the flame signal and its internal flame control
system is non-functional. 10.16.6 Function of input 6
Parameter I066
10.16.2 Function of input 2
To define the input signal for terminal 6.
Parameter I062
For parameter values and descriptions, see page 104
To define the input signal for terminal 2.
(Function of input 1).
For parameter values and descriptions, see page 104
(Function of input 1). 10.16.7 Function of input 7
Parameter I067
10.16.3 Function of input 3
To define the input signal for terminal 7.
Parameter I063
For parameter values and descriptions, see page 104
To define the input signal for terminal 3.
(Function of input 1).
For parameter values and descriptions, see page 104
(Function of input 1). 10.16.8 Function of input 35
Parameter I068
10.16.4 Function of input 4
To define the input signal for terminal 35.
Parameter I064
On a BCU..E1 (power supply via L1), this input should
To define the input signal for terminal 4.
be reserved for the safety interlock signal (I068 = 4). On
For parameter values and descriptions, see page 104
a BCU..E0, this input is connected to the power supply
(Function of input 1).
for the safety-relevant outputs and cannot be param-
eterized otherwise.
For all other parameter values and descriptions, see
page 104 (Function of input 1).
▼

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Parameters
10.16.9 Function of input 36 Parameter I071 = 1: sensor 1
Parameter I069 Parameter I071 = 2: sensor 2
To define the input signal for terminal 36. Parameter I071 = 3: sensor 3
A sensor may be connected to this input (I069 = 1, 2 For all other parameter values and descriptions, see
or 3) if necessary. page 104 (Function of input 1).
Parameter I069 = 1: sensor 1
10.16.12 Function of input 39
Parameter I069 = 2: sensor 2 Parameter I072
Parameter I069 = 3: sensor 3 To define the input signal for terminal 39.
For all other parameter values and descriptions, see For parameter values and descriptions, see page 104
page 104 (Function of input 1). (Function of input 1).
10.16.10 Function of input 37 10.16.13 Function of input 40
Parameter I070 Parameter I073
To define the input signal for terminal 37. To define the input signal for terminal 40.
A sensor may be connected to this input (I070 = 1, 2 For parameter values and descriptions, see page 104
or 3) if necessary. (Function of input 1).
Parameter I070 = 1: sensor 1
10.16.14 Function of input 41
Parameter I070 = 2: sensor 2 Parameter I074
Parameter I070 = 3: sensor 3 To define the input signal for terminal 41.
For all other parameter values and descriptions, see For parameter values and descriptions, see page 104
page 104 (Function of input 1). (Function of input 1).
10.16.11 Function of input 38
Parameter I071
To define the input signal for terminal 38.
A sensor may be connected to this input (I071 = 1, 2
or 3) if necessary.

BCU 480 · Edition 11.19 106

Replacement possibilities

11 Replacement possibilities
Burner control units BCU 480 can be replaced by the next-generation devices BCU 480 (2019).
By comparison to the previous generation, the next-generation BCU 4 (2019) units feature new technologies and
functions which can be freely parameterized.
Code Description of BCU (previous generation) Description of BCU (2019) Code2)
BCU Burner control unit
Series 4 burner control unit BCU 4
4 Series 4
80 Version for pilot and main burners Series 480 80
3; 5; 10 1st safety time on start-up tSA [s] Can be adjusted using parameter A094: 2 to 15 s 
/3; /5 2nd safety time on start-up tSA [s] Can be adjusted using parameter A096: 2 to 15 s 
/1; /2 Safety time during operation tSB [s] Can be adjusted using parameter A019: 0, 1, 2, 3, 4 s 
In conjunction with LM..F1 = with interface for IC 40,
L1) Air valve control 
LM 400..F3 = with air valve control
51); 151); Can be adjusted using parameter A039 (Over-run time): 0 to
Low fire over-run time [s] 
251) 60 s
W Mains voltage: 230 V AC, -15/+10%, 50/60 Hz Mains voltage: 230 V AC, -15/+10%, 50/60 Hz W
R 115 V AC, -15/+10%, 50/60 Hz 120 V AC, -15/+10%, 50/60 Hz Q
11) Ignition transformer: TZI 5-15/100 Ignition transformer: 5 kV, 15 mA, 100% duty cycle 1
21) TZI 7-25/20 8 KV, 20 mA, 19% duty cycle 2
31) TZI 7,5-12/100 8 KV, 12 mA, 100% duty cycle 3
81) TZI 7,5-20/33 8 KV, 20 mA, 33% duty cycle 8
GB1) Front film in English with additional stickers in D, F, I, NL, E Set of language stickers in GB, F, NL, I, E, see accessories 
Flange plate: none P0
standard P1
M32 P2
P1) Industrial plug connector industrial plug connector, 16-pin P3
PROFIBUS P6
conduit P7
No valve proving system C0
– With TC and POC valve proving system C1
With POC valve proving system C2
D21) High temperature operation in conjunction with: … UVS No high temperature operation D0
D31) … ionization or UVD For high temperature operation D1
S2 – 31) Number of start-up attempts, pilot burner Can be adjusted using parameter A007: 1, 2 or 3 
/2 – 31) Number of start-up attempts, main burner Can be adjusted using parameter A008: 1, 2 or 3 
▼
BCU 480 · Edition 11.19 107
Replacement possibilities

Code Description of BCU (previous generation) Description of BCU (2019) Code2)

Pressure switches: none 0
A 1) Air flow monitoring air pressure switch 1
O1) POC switch feedback gas pressure switch 2
air and gas pressure switch 3
Flame control can be adjusted separately for pilot and main
U1) Preparation for UV sensor for continuous operation UVD 1 burners using parameter I004:
C1), 3) Additional signal distribution 
ionization, UVS or UVC
With optional bus module:
BCM 400..B1 for PROFIBUS
B11) For PROFIBUS DP BCM 400..B2 for PROFINET 
BCM 400..B3 for EtherNet/IP
With bus module BCM 400..B1: 9-pin D-Sub connector
/11) 9-pin D-Sub bus plug connector With bus module BCM 400..B2/B3: two RJ45 sockets 
Energy supply: via safety interlock input E0
E14) Power management via phase (L1) via phase (L1) E1
 = standard,  = available.
1) If “none”, this specification is omitted.
2) Complete type codes and selection tables for the next-generation BCU 4 and power module BCM 400, see from page 109 (Selection).
3) BCU..C with additional PCB for voltage distribution to the UV sensor for continuous operation. Can be used as a sub-distribution board
due to the low number of outputs. The new BCU 4 (2019) has an adequate number of (parameterizable) inputs and outputs as well as
contacts. When making the replacement, check whether the additional sub-distribution board is still required.
4) If “none”, this specification is omitted. The energy required is supplied via the safety interlocks.

BCU 480 · Edition 11.19 108

Selection

12 Selection
12.1 Burner control unit BCU
Q W 1 2 3 8 P0 P1 P2 P3 P6 P7 C0 C1 C2 D0 D1 0 2 0 K0 K1 K2 E0 E1
BCU 480                         
 = standard,  = available
Order example
BCU 480W2P1C1D00K1E1
12.1.1 Type code
Code Description Code Description
BCU 4 Series 4 burner control unit E0 Energy supply: via safety interlocks
E1 via L1
80 Series 480
Q Mains voltage: 120 V AC, 50/60 Hz
W 230 V AC, 50/60 Hz
1 Ignition transformer: 5 kV, 15 mA, 100% duty cycle
2 8 kV, 20 mA, 19% duty cycle
3 8 kV, 12 mA, 100% duty cycle
8 8 kV, 20 mA, 33% duty cycle
P0 Flange plate: none
P1 standard
P2 M32
P3 industrial plug connector, 16-pin
P6 PROFIBUS
P7 conduit
C0 No valve proving system
C1 With TC and POC valve proving system
C2 With POC valve proving system
D0 No high temperature operation
D1 For high temperature operation
0 Input functions: none
2 LDS
0 Pressure switches: none
K0 No connection plugs
K1 Connection plugs with screw terminals
K2 Connection plugs with spring force terminals

BCU 480 · Edition 11.19 109

Selection

12.2 Power module LM 400

Q W F0 F1 F3 O0 O1 O2 E0 E1 K0 K1 K2
LM 400             
 = standard,  = available

Order example
LM 400WF100E1K1
12.2.1 Type code
Code Description
LM Power module
400 For series 400
Q Mains voltage: 120 V AC, 50/60 Hz
W 230 V AC, 50/60 Hz
F0 Air actuator: none
F1 with IC 40 interface
F3 with air valve control
O0 Optional outputs: none
O1 not fail-safe
O2 fail-safe
E0 Energy supply: via safety interlocks
E1 via L1
K0 No connection plugs*
* Connection plugs for the power module are supplied with the
BCU..K1 and BCU..K2.

BCU 480 · Edition 11.19 110

Project planning information

13 Project planning information Securing the device from outside

The unit remains closed.
13.1 Installation Attach the BCU using four self-tapping screws
Installation position: vertical (cable glands pointing (M6 x 20 mm, supplied with the unit).
downwards) or down flat.
mm
185 "
7.28

8888

163 mm
6.42"
Distance between BCU and burner: recommended
< 1 m (3.3 ft), max. 5 m (16.4 ft). For other mounting options using a fastening set or ex-
When installing, ensure that there is sufficient space to ternal securing bars, see page 116 (Accessories).
open the BCU.
13.2 Commissioning
Securing the device from inside Do not start the BCU until the parameter settings and
wiring are correct and the faultless processing of all
input and output signals complies with the local stand-
ards.

Screw on the BCU with four screws, Ø 4 mm, min.

length 15 mm.

BCU 480 · Edition 11.19 111

Project planning information

13.3 Electrical connection

The BCU is designed for connection to a 1-phase sys-
tem. All inputs and outputs have a one-phase mains
supply. Other connected burner control units must use
the same phase of the mains supply.
The national standards and safety requirements must
be satisfied. If the BCU is operated in ungrounded/IT
systems, an insulation monitoring device must be pro-
vided to isolate it from the mains in the event of a fault.
The cabling of the safety circuits (e.g. pressure switches,
gas valves) outside enclosed installation spaces must
be protected from mechanical damage and stress (e.g.
vibration or bending) as well as short-circuits, short-
circuits to ground and cross-circuits.
Signal and control line for screw terminals max.
2.5 mm2 (AWG 12), for spring force terminals max.
1.5 mm2 (AWG 16).
Do not route BCU cables in the same cable duct as
frequency converter cables or cables emitting strong
fields.
External electrical interference must be avoided.

BCU 480 · Edition 11.19 112

Project planning information
13.3.1 Safety current inputs IN = current of the sensor/contactor with the lowest
Actuation of the safety current inputs only with switch- switching capacity
gear featuring mechanical contacts. If switchgear with Suitable fuse = 0.6 × IN
semi-conductor contacts is used, the safety current
inputs must be connected using relay contacts.
To safeguard the safety current inputs, the fuse must be
designed so that the sensor with the lowest switching
capacity is protected.
The cabling outside enclosed installation spaces must
be protected from mechanical damage and stress (e.g.
vibration or bending) as well as short-circuits, short-
circuits to ground and cross-circuits.

L1
0,6 × IN

P
Start 2
A
HT LDS
Start 1

L 1 2 3 4 5 6 7 35 39 40 41 BCU 465 82 81 80 85 86 87 92 91 90 95 9
F2
(BCU..E0)
F1
(BCU..E1) LM 400..F3
F 3,15 A
N1
N1 F3 3,15 A UA-Sk vLuft
O
230 V
UVS

I 1
51 21 BM N1 N1 N1 N1 N1 N1 V1 V2 N1 V3 N1 N1
N1

PE L N L N L N
N PE 22 23 52 53 BM 54 24 55 25 56 26 57 27 36 58 28 37 59 29 38 60 30 61 31 62 32 65 34 66

V1 V2 V3
pU
Calculation 2 PE PE PE PE
I Z

BCU 480 · Edition 11.19 PE PE 113

DW 1 DW 2 TC
Project planning information

13.4 Actuators 13.7 Overload protection

If actuators are used, the start gas rate of the burners To protect the unit against overload by frequent cycling,
must be limited for SIL 3 applications in compliance only a specific number of start-up attempts can be car-
with the standard. ried out by the BCU. The maximum number of start-up
attempts per minute depends on the safety time tSA
13.5 Parameter chip card and the ignition time t Z .
The parameter chip card must be installed in the unit for
tSA Device type Max. number
the BCU to operate. The parameter chip card contains [s] Ignition transformer ID number [n/min.]
the valid parameter settings for the BCU. If a BCU is 3 6
BCU..1
replaced, the parameter chip card can be removed from 5 6
5 kV, 15 mA, 100% duty cycle
10 3
the old unit and inserted into the new BCU. The BCU
3 3
must be disconnected from the electrical power supply 5 BCU..2 2
8 kV, 20 mA, 19% duty cycle
for this purpose. The valid parameters are then adopted 10 1
by the new BCU. The old device and the new BCU must 3 6
BCU..3
have an identical type code. 5 4
8 kV, 12 mA, 100% duty cycle
10 2
13.6 K-SafetyLink 3
BCU..8
4
5 3
In furnace control systems, consisting of FCU and 8 kV, 20 mA, 33% duty cycle
10 2
BCU 4, the SafetyLink communications protocol is
used to transfer safety-critical signals between the If too many start-up attempts are made, 53 flashes
FCU and BCU. The data transfer can be enabled using on the display to indicate a fault.
parameter A081. The FCU must support the function
for communicating via K-SafetyLink.

BCU 480 · Edition 11.19 114

Project planning information

13.8 Calculating the safety time tSA

See www.adlatus.org

BCU 480 · Edition 11.19 115

Accessories

14 Accessories 14.3 BCSoft

The current software can be downloaded from our In-
14.1 High-voltage cable
ternet site at www.docuthek.com. To do so, you need to
FZLSi 1/7 up to 180°C, register in the DOCUTHEK.
Order No.: 04250410.
14.3.1 Opto-adapter PCO 200
FZLK 1/7 up to 80°C,
Order No.: 04250409.

14.2 Industrial plug connector, 16-pin

Including BCSoft CD-ROM,

Order No.: 74960625.
For further information, see 40 (BCSoft).

Order No.: 74919469 14.4 Connection plug set

For wiring the BCU.

Connection plugs with screw terminals,

Order No.: 74924876.
Connection plugs with spring force terminals, 2 con-
nection options per terminal,
Order No.: 74924877.

BCU 480 · Edition 11.19 116

Accessories

14.5 Set of language stickers

mm
225
To affix to the cover, with program step/fault message mm
212
descriptions in English, French, Dutch, Spanish and
Italian,
Order No. 34336970.

185 mm
200 mm
14.6 Fastening set
To ensure a gap between the BCU and the mounting
surface with higher temperatures.
74960414 Ø 4mm

mm
174 14.8 Bus module BCM 400
Communication interface for connecting the BCU to an
automation system.

263 mm
22 mm 45
230 mm

mm
12 mm
7 mm
16.5 mm

m
222 m
20 mm

BCM 400..B1 BCM 400..B2, BCM 400..B3

74960422
Bus module Bus system Order No.
BCM 400S0B1/1-0 PROFIBUS 74960690
14.7 External securing bars BCM 400S0B2/3-0 PROFINET 74960691
The external securing bars are screwed on from inside BCM 400S0B3/3-0 EtherNet/IP 74960692
the unit.

BCU 480 · Edition 11.19 117

Accessories

14.9 Flange plates Order No. Version Description

For improved cable routing to ensure simple installa- Standard
74960706 8 x M20, 2 x M16 cable glands
(BCU..P1)
tion/removal of the BCU. Depending on the version, M32 1 x M32, 6 x M20, 2 x M16 cable
749607071) (BCU..P2) glands
also with pre-wired connection plugs for PROFIBUS or
16-pin industrial plug connector. 16-pin plug, 1 x 16-pin industrial plug, 2 x M25, 6
74960709 wired x M16 cable glands
(BCU..P3)
PROFIBUS plug, 1 x PROFIBUS plug, 6 x M20, 2 x
749607112) wired M16 cable glands
(BCU..P6)
Conduit With boreholes for conduit
74960712
(BCU..P7) connections
1) Recommended for PROFINET oder Ethernet.
2) Recommended for replacement of a previous version of
74960706 the BCU for PROFIBUS. The PROFIBUS plug is identical.

74960712

74960707

74960709
74960711

BCU 480 · Edition 11.19 118

BCM 400

15 BCM 400 15.3 Electrical connection

Use only cable and plug components which comply
15.1 Application
with the relevant PROFIBUS, PROFINET or EtherNet/IP
specifications.
Cable length between 2 fieldbus subscribers: max.
100 m (328 ft).
Installation of the communications network pursuant
to IEC 61918.
Protect the communications network against unau-
thorized access.
BCM..B1
Wire control signals that are relevant for safety, such as
The bus module BCM 400 is used as a communication
the safety interlocks and digital input, separately.
interface for devices of the BCU 4 (2019) product fam-
ily for connection to a fieldbus communications system The purge signals can be transferred via the bus com-
(PROFIBUS, PROFINET or EtherNet/IP). Networking munication or by a separate cable via terminal.
via the fieldbus enables the BCU to be controlled and ▼
monitored by an automation system (e.g. PLC).

15.2 Function
The bus system transfers the control signals for start-
ing, resetting and for controlling the air valve to purge
the furnace or kiln or for cooling in start-up position
and heating during operation from the automation
system (PLC) to the BCM. In the opposite direction, it
sends operating status, the level of the flame signal and
the current program step.

BCU 480 · Edition 11.19 119

BCM 400
Data cables A and B must not be reversed.
BCU..B1/1
2A 2B 1A 1B
ON ON
OFF OFF

PROFIBUS DP
BCM..B2/B3
Connect the shield on both sides and over a wide area
Use shielded RJ45 plugs.
with shield clips in the plug.
Switch on the terminal resistors on the first and last Installation guidelines
subscriber in the segment. For PROFIBUS, PROFINET, see www.profibus.com,
for Ethernet installation guidelines, see www.odva.org.
The power supply for the bus terminator is provided by
the BCU. The bus terminator can be activated in the
PROFIBUS plug connector.
Ensure there is an equipotential bond between the de-
vices.
To connect the BCM..B1 to the PROFIBUS fieldbus
communications system, use an RS 485 9-pin PROFI-
BUS plug connector with a deactivatable bus termi-
nator and axial cable routing, e.g. 6GK1500-0FC00
or 6GK1500-0EA02 from Siemens. If other connec-
tors are used, ensure that metal parts are adequately
grounded.
BCU..P6: for connection to the BCU mounting plate,
use only a 9-pin Variosub PROFIBUS plug connector
with a deactivatable bus terminator,
Order No. 74960431

BCU 480 · Edition 11.19 120

BCM 400

15.4 Installation 15.6 Technical data

Insert the bus module in the slot provided. Electrical data
Power consumption: 1.2 VA.
Power loss: 0.7 W.
Mechanical data
Dimensions (W × H × D):
96 × 63 × 23 mm (3.78 × 2.48 × 0.91 inch).
Weight: 0.3 kg.
Ambient conditions
Avoid direct sunlight or radiation from red-hot surfaces
on the unit.
Avoid corrosive influences, e.g. salty ambient air or SO2.
15.5 Selection The unit may only be stored/installed in enclosed
Code Description rooms/buildings.
BCM Bus module This unit is not suitable for cleaning with a high-pres-
400 Series 400
sure cleaner and/or cleaning products.
S0 Standard communication
S1 SafetyLink Ambient temperature:
B1 PROFIBUS DP1) -20 to +70°C (-4 to +158°F),
B2 PROFINET2)
B3 EtherNet/IP3) no condensation permitted.
/1 9-pin D-Sub Enclosure: IP 20 pursuant to IEC 529.
/3 Two RJ45 sockets
-0 – Installation location: min. IP 65 (for installation in
-3 Three-point step control via bus
1) Order No.: 74960690
BCU 4xx).
2) Order No.: 74960691 Permitted operating altitude: < 2000 m AMSL.
3) Order No.: 74960692

BCU 480 · Edition 11.19 121

Technical data

16 Technical data Total current for the simultaneous activation of the

outputs for air valve and actuator (terminals 65, 66
16.1 Electrical data and 67): max. 2 A.
Mains voltage: Signalling contact for operating and fault signals:
BCU..Q: 120 V AC, -15/+10%, 50/60 Hz, ± 5%,
max. 1A, cos φ = 1 (external fuse required).
BCU..W: 230 V AC, -15/+10%, 50/60 Hz, ± 5%.
Number of operating cycles:
Power consumption: 10 VA,
The fail-safe outputs (valve outputs V1, V2, V3 and V4)
for grounded and ungrounded mains.
and the air valve output are monitored for correct func-
Flame control: tioning and are thus not subject to a max. number of
with UV sensor or flame rod. operating cycles.
For intermittent or continuous operation. Control actuator (terminals 60, 61, 62, 63 and 64):
Flame signal current: 1,000,000,
Ionization control: 1 – 25 �A, signalling contact for operating signals (terminals 95,
UV control: 1 – 35 �A. 96 and 97):
Ionization cable, UV cable: 1,000,000,
max. 50 m (164 ft). signalling contact for fault signals (terminals 80, 81
and 82):
Contact rating:
max. 25,000,
Valve outputs V1, V2, V3, V4 and V5 (terminals 60, 61,
On/Off button:
62, 63 and 64): max. 1 A each, cos φ = 1.
max. 10,000,
Actuator outputs (terminals 65, 66 and 67): max. 1 A Reset/Information button:
each, cos φ = 1. max. 10,000.
Air valve output (terminal 65): max. 1 A, cos φ = 1.
▼
Ignition transformer (terminal 51): max. 2 A.
Total current for the simultaneous activation of the
valve outputs (terminals 60, 61, 62, 63 and 64) and of
the ignition transformer (terminal 51), protected by F1/
F2: max. 2.5 A.

BCU 480 · Edition 11.19 122

Technical data
Input voltage of signal inputs: 16.2 Mechanical data
Rated value 120 V AC 230 V AC Weight: 5 kg.
Signal “1” 80 – 132 V 160 – 253 V
Signal “0” 0 – 20 V 0 – 40 V Dimensions (W × H × D): 200 × 230 × 135 mm.
Connections:
Signal input current:
Screw terminals:
Signal “1” max. 5 mA
nominal cross-section 0.2 mm²,
Fuses, replaceable, F1/F2/F3: T 3.15A H, wire cross-section (rigid) min. 0.2 mm²,
pursuant to IEC 60127-2/5. wire cross-section (rigid) max. 2.5 mm²,
Does not meet the requirements for safety extra-low wire cross-section AWG/kcmil min. 24,
voltage (SELV/PELV). wire cross-section AWG/kcmil max. 12.
Spring force terminals:
Ignition transformer
nominal cross-section 2 x 1.5 mm²,
Ignition Input Output
Burner transformer wire cross-section min. 0.2 mm²,
control unit V AC Hz* A* V AC mA*
(material No.) wire cross-section AWG min. 24,
TRS515PCISOH2
BCU..W1 230 50 (60) 0.4 (0.3) 5000 15 (10) wire cross-section AWG max. 16,
(34340585)
TRS515PCISOH1
BCU..Q1 120 50 (60) 0.9 (0.6) 5000 15 (11) wire cross-section max. 1.5 mm².
(34340581)
TRE820PISOH2
BCU..W2 230 50 (60) 1.0 (0.7) 8000 20 (16)
(34340586)
TRE820PISOH1
BCU..Q2 120 50 (60) 1.9 (1.4) 8000 20 (16)
(34340582)
TRS812PCISOH2
BCU..W3 230 50 (60) 0.6 (0.4) 8000 12 (9)
(34340587)
TRS812PCISOH1
BCU..Q3 120 50 (60) 1.2 (0.9) 8000 12 (9)
(34340583)
TRS820PISOH2
BCU..W3 230 50 (60) 1.0 (0.7) 8000 20 (16)
(34340587)
TRS820PISOH1
BCU..Q3 120 50 (60) 1.7 (1.3) 8000 20 (16)
(34340583)
* Values in brackets apply to 60 Hz.

BCU 480 · Edition 11.19 123

Technical data

16.3 Ambient conditions 16.4 Dimensions

Avoid direct sunlight or radiation from red-hot surfaces
m
on the unit. 202 m 135
mm
Avoid corrosive influences, e.g. salty ambient air or SO2.
The unit may only be stored/installed in enclosed
rooms/buildings that are not accessible to the public.
This unit is not suitable for cleaning with a high-pres-
sure cleaner and/or cleaning products.
230
Ambient temperature: mm
-20 to +70°C (-4 to +158°F),
no condensation permitted.
Enclosure: IP 65 pursuant to IEC 529.
Safety class: 1
Pollution degree: internal environment: 2, external envi- m
212 m
ronment: 4.
Permitted operating altitude: < 2000 m AMSL.

270
mm

BCU 480 · Edition 11.19 124

Converting units

17 Converting units Mean probability of dangerous failure PFHD of

See www.adlatus.org individual safety functions
Burner control with 2 gas valves 23.2 × 10 -9 1/h
Burner control with 3 gas valves 28.5 × 10 -9 1/h
18 Safety-specific characteristic values for SIL Valve check 15.0 × 10 -9 1/h
and PL Proof of closure 3.3 × 10 -9 1/h
Flame control 8.4 × 10 -9 1/h
Certificates – see Docuthek.
Temperature monitoring 2.2 × 10 -9 1/h
For systems up to SIL 3 pursuant to EN 61508. Air pressure switch monitoring 3.3 × 10 -9 1/h
Pursuant to EN ISO 13849-1:2006, the BCU can be Gas pressure switch monitoring 3.3 × 10 -9 1/h
used up to PL e. Purge with air pressure switch 4.3 × 10 -9 1/h
K-SafetyLink 1.0 × 10 -9 1/h
Suitable for Safety Integrity Level Up to SIL 3 Safety interlocks (limits) 2.2 × 10 -9 1/h
Diagnostic coverage DC 91.3% Valve check with redundant pressure switch 12.9 × 10 -9 1/h
Type of subsystem Type B to EN 61508-2:2010 Air pressure switch monitoring with red. pressure switch 1.3 × 10 -9 1/h
High demand mode pursuant to EN Gas pressure switch monitoring with red. pressure switch 1.3 × 10 -9 1/h
Mode of operation 61508-4:2010
Purge with red. air pressure switch 2.3 × 10 -9 1/h
Mean probability of dangerous 32.9 × 10 -9 1/h on BCU 4xx..F1,
failure PFHD 38.3 × 10-9 1/h on BCU 4xx..F3
Relationship between the Performance Level (PL)
Mean time to dangerous failure MTTFd = 1/PFHD
MTTFd and the Safety Integrity Level (SIL)
Safe failure fraction SFF 99.0% PL SIL
a –
b 1
c 1
d 2
e 3

Max. service life under operating conditions:

10 years after date of production.
For a glossary of terms, see page 130 (Glossary).

BCU 480 · Edition 11.19 125

Safety information in accordance with EN 61508-2

19 Safety information in accordance with Software class:

Corresponds to software class C which operates in a
EN 61508-2 similar double-channel architecture with comparison.
19.1 General
19.2 Interfaces
Scope of application
Electrical wiring
as set out in “Industrial thermoprocessing equipment –
Type of wiring:
Part 2: Safety requirements for combustion and fuel
Attachment type X to EN 60730-1.
handling systems” (EN 746-2) when used with fuels
and oxidants. Grounding: via PE wire connection.

The BCU 4 is suitable for continuous operation (pursu- Internal voltages are neither SELV nor PELV. Floating
ant to EN 298:2012-12, Section 3.126) and for inter- contacts meet the requirements for SELV.
mittent operation (pursuant to EN 298:2012-11, Sec-
19.3 Communication
tion 3.127).
Safety over EtherCAT® technology (FSoE, FailSafe over
Type of action EtherCAT) is used for K-SafetyLink communication.
The automatic action corresponds to Type 2 pursuant Safety over EtherCAT® is a registered trademark and
to EN 60730-1. patented technology licensed by Beckhoff Automation
Behaviour under fault conditions GmbH, Germany.
Switching off the safety-relevant output signals: The K-SafetyLink technology complies with SIL 3 in ac-
The output signals are switched off electronically in cordance with EN 61508 and is standardized pursuant
accordance with the criteria of automatic action type to IEC 61784-3-12 and ETG 5100.
B.V.AC.AD.AF.AG.AH (pursuant to EN 60730-2-5:2015, Safety over EtherCAT® uses the fail-safe principle which
Section 6.4.3.). means that a safe state is restored in the case of an
Maximum reaction time in the event of a flame failure: inactive signal. In the case of communication errors, all
This corresponds to the safety time during operation signals are interpreted as inactive.
and can be parameterized to between 1 and 4 s. Safety-relevant data are transmitted on the basis of the
black channel principle.
▼

BCU 480 · Edition 11.19 126

Safety information in accordance with EN 61508-2
All devices connected to the communications system
must meet the requirements for safety extra-low volt-
age (SELV/PELV) (EN 6730-1).
The end user must ensure the unique setting and pa-
rameterization of the SafetyLink address within the
Ethernet network.
The setting and assignment of the addresses must be
verified before commissioning using the verification
procedure described in the extended documentation.

19.4 SIL and PL for BCU 4

SIL Safety Integrity Level/PL Performance Level
See page 125 (Safety-specific characteristic values
for SIL and PL).

BCU 480 · Edition 11.19 127

Maintenance

20 Maintenance
The fail-safe outputs (valve outputs V1, V2, V3 and V4)
of the power module are monitored for correct func-
tioning. In the event of a fault, the system is set to a safe
status using a second shut-down path (isolation of the
valve outputs from the mains). In the event of a defect
(e.g. fault E 36), the power module must be replaced.
Order No. for the power module, see type label:

The device and user statistics can be displayed using

the engineering tool BCSoft for further diagnostics and
troubleshooting. The user statistics can be reset using
engineering tool BCSoft.

BCU 480 · Edition 11.19 128

Legend

21 Legend PZL Pressure switch for minimum pressure

Ready for operation PDZ Differential pressure switch
Safety interlocks (limits) M
Actuator with butterfly valve
Control element position check
TC Tightness control
Controlled air flow pu/2 Half of the inlet pressure
Remote reset pu Inlet pressure
pd Outlet pressure
LDS Safety limits (limits during start-up)
Vp1 Test volume
Gas valve GZL
Valve with proof of closure switch
Air valve
Three-point step switch
Air/gas ratio control valve Input/Output, safety circuit
IN Current consumption of sensor/contactor
Pilot burner (burner 1) tL Tightness control opening time
tM Measurement time during tightness test
Main burner (burner 2)
tP Tightness control test period (= 2 x tL + 2 x tM)
P Purge tFS Flame proving period
A External air valve control tMP Minimum pause time
tNL Over-run time
1 Flame signal, pilot burner (burner 1)
t SA Safety time on start-up
2 Flame signal, main burner (burner 2) tSB Safety time during operation
1 Operating signal, pilot burner (burner 1) tVZ Pre-ignition time
2 Operating signal, main burner (burner 2) tPV Pre-purge time
Fault signal tRF Controller enable signal delay time

Start 1/ϑ1 Start-up signal, pilot burner (burner 1)

Start 2/ϑ2 Start-up signal, main burner (burner 2)
HT Input for high temperature operation
PZ Pressure switch for tightness control (TC)
PZH Pressure switch for maximum pressure

BCU 480 · Edition 11.19 129

Glossary

22 Glossary ignition time is either 1, 2, 3 or 6 s (depending on safety

time tSA1 selected).
22.1 Waiting time tW
In standby, the waiting time tW starts to elapse in the 22.5 Safety time during operation tSB
background. During this time, a self-test is conducted
to detect errors in internal and external circuit compo- 08 08 88
L L1
nents. The burner will not be started during the waiting 35
1 ϑ1
time. Any burner start will be delayed by the BCU until 51
60 V1
the waiting time has elapsed 22 1
95 1
5 ϑ2
22.2 Safety time on start-up tSA1 61 V2
23 2
96 2
This refers to the period of time between switching on 82
and switching off of the gas valve, when no flame signal tSB
t
is detected. The safety time on start-up tSA1 (2 to 15 s)
is the minimum operating time of the burner control In the event of a flame failure during operation or an in-
unit and burner 1. terruption of the safety current inputs, the fuel supply is
interrupted within the safety time tSB.
22.3 Safety time on start-up tSA2 The default safety time during operation tSB in accord-
This refers to the period of time between switching on ance with EN 298 is 1 s. Under EN 746-2, the safety
and switching off of the gas valve, when no flame signal time of the installation during operation (including clos-
is detected. The safety time on start-up tSA2 (2 to 15 s) ing time of the valves) must not exceed 3 s. Note the
is the minimum operating time of the burner control requirements of the standards!
unit and burner 2.
Under NFPA 86, section 8.10.3*, the maximum flame
22.4 Ignition time t Z failure response time shall be ≤ 4 s.

If no malfunction is detected during the waiting time tW,

the ignition time t Z then starts to elapse. Voltage is
supplied to the pilot gas valve and the ignition trans-
former and the burner is ignited. The duration of the

BCU 480 · Edition 11.19 130

Glossary

22.6 Safety interlocks 22.8 Safety shut-down with subsequent

The limiters in the safety interlock (linking of all the rel- lock-out (fault lock-out)
evant safety-related control and switching equipment A fault lock-out is a safety shut-down with subsequent
for the use of the application, e.g. safety temperature lock-out. The system can only be restarted following
limiter, minimum/maximum gas pressure) must isolate manual reset. The protective system cannot be reset by
input  from the voltage supply. mains failure.

22.7 Safety shut-down In the event of a fault lock-out, the fault signalling con-
tact closes, the display flashes and shows the current
The burner control unit performs a safety shut-down
program step, see page 53 (Fault signalling). The
immediately after receiving a signal from a safety de-
gas valves are disconnected from the electrical power
vice or after a fault is detected (e.g. flame or air pressure
supply. The fault signalling contact opens if the mains
failure). The safety shut-down prevents operation of the
voltage fails.
burner by closing the fuel shut-off valves and deacti-
vating the ignition device. In order to restart, the BCU can only be reset manually
using the button on the front panel, the OCU or the re-
For this, the BCU disconnects the gas valves and the ig-
mote reset input (terminal 3).
nition transformer from the electrical power supply. The
operation signalling contact and the controller enable 22.9 Warning signal
signal are deactivated. The fault signalling contact re-
The BCU reacts to operating faults, e.g. in the case of
mains open. The display blinks and displays the current
permanent remote resets, with a warning signal. The
program step, see page 53 (Fault signalling).
display blinks and shows the corresponding warning
After a safety shut-down, the BCU can restart auto- message. The warning signal ends once the cause has
matically. been eliminated.
The program sequence continues. No safety shut-down
or fault lock-out occurs.

BCU 480 · Edition 11.19 131

Glossary

22.10 Timeout 22.13 Diagnostic coverage DC

For some process faults, a timeout phase elapses be- Measure of the effectiveness of diagnostics, which may
fore the BCU reacts to the fault. The phase starts as be determined as the ratio between the failure rate of
soon as the BCU detects the process fault and ends detected dangerous failures and the failure rate of total
after 0 to 250 s. A safety shut-down or fault lock-out dangerous failures
is then performed. If the process fault ends during the NOTE: Diagnostic coverage can exist for the whole or
timeout phase, the process continues as before. parts of a safety-related system. For example, diagnos-
tic coverage could exist for sensors and/or automation
22.11 Air actuator
system and/or control elements. Unit: %.
The air actuator can be used from EN ISO 13849-1:2008
– for cooling,
22.14 Mode of operation
– for purging,
IEC 61508 describes two modes of operation for safety
– to control the burner capacity in ON/OFF mode and
functions. These are low demand mode and high de-
in High/Low mode when using a pneumatic air/gas
mand or continuous mode.
ratio control system.
In low demand mode, the frequency of demands for op-
22.12 Safe failure fraction SFF eration made on a safety-related system is not greater
Fraction of safe failures related to all failures, which are than one per year and is not greater than twice the
assumed to appear proof-test frequency. In high demand mode or continu-
from EN 13611/A2:2011 ous mode, the frequency of demands for operation
made on a safety-related system is greater than one per
year or greater than twice the proof-test frequency.
See also IEC 61508-4

BCU 480 · Edition 11.19 132

Glossary

22.15 Probability of dangerous failure PFHD

Value describing the likelihood of dangerous failure per
hour of a component for high demand mode or con-
tinuous mode. Unit: 1/h.
from EN 13611/A2:2011

22.16 Mean time to dangerous failure

MTTFd
Expectation of the mean time to dangerous failure
from EN ISO 13849-1:2008

BCU 480 · Edition 11.19 133

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Osnabrück

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BCU 480 · Edition 11.19