7
418
ISO 9001
Gas Burner Controls
LGA...
The LGA... are used for the startup and supervision of atmospheric gas burners
of low to medium capacity, without fan assistance, in intermittent operation.
The LGA... and this data sheet are intended for use by OEMs which integrate the
gas burner controls in their products.
Use
The flame is supervised with an ionization current ionization electrode.
Using the appropriate adapters, the LGA... can replace their predecessor types LFI7...
and LFI5... in terms of both function and size (refer to Ordering).
LGA41.173A27 and LGA52.171B27 can also be used on direct fired air heaters (WLE
to DIN 4794).
CC1N7418en
27.06.2000
Siemens Building Technologies
Landis & Staefa Division
Warning notes
To avoid injury to persons, damage to property and the environment, the following warning notes should be observed.
Do not open, interface with or modify the unit.
Before performing any wiring changes in the connection area of the LGA..., completely isolate the burner control from the mains supply (all-polar disconnection)
Ensure protection against electric shock hazard by providing appropriate protection
for the burner controls terminals
Check wiring and all safety functions
Press the lockout reset button only manually, without using any tools or pointed
objects
Fall or shock can adversely affect the safety functions. Such units may not be put
into operation even if they do not exhibit any damage
Mounting notes
The relevant national safety regulations must be complied with.
Siting the ionization
electrode
The ionization current ionization electrode and the ignition electrode must be positioned such that the ignition spark cannot arc over to the ionization electrode
The position and the polarity of the ignition electrode can adversely affect the magnitude of the flame signal. Reversal of polarity of the ignition transformers connections on the primary side usually solves the problem
Since the burner bars form the earthed counter-electrode, the burner must be adjusted such that the flame is hot and stable and in firm contact with the burner bars.
With pulsating flames or yellow-burning flames resulting from lack of air, a very low
or even no ionization current is generated so that the burner control will initiate
lockout
2/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Installation notes
Only with the LGA41...
Only with the LGA52... /
LGA63...
Electrical connection of
the ionization electrode
Installation and commissioning work must be carried out by qualified staff
Observe the permissible length and shielding of the detector cable (refer to Technical data)
Always run the ignition cables separate from the unit and other cables while observing the greatest possible distances
To isolate the burner control from the mains supply, use an all-polar switch with a
contact gap of at least 3 mm
Secure the earthing lug in the terminal base with a metric screw and a lockwasher
or similar
Switches, fuses, earthing, etc., must be in compliance with local regulations. Primary fuse max. 10 A (slow)
Make absolutely certain that life conductor L is connected to terminal 1. Otherwise, no flame signal will be generated
Connect the gas pressure monitor and other monitoring devices - whose contacts
must be closed from startup to controlled shutdown - in series with R and W
If the fully closed position of the main gas valve BV2 shall be checked on
startup, the closed position contact must be included in the loop between terminals
9 and 3. In addition, the connecting links between terminals 9 and 11 and 8 and 3
must be fitted
During the startup sequence, terminal 6 carries voltage and may not be used as an
auxiliary terminal
The auxiliary contact of a gas valve for checking the fully closed position must be
included in the loop between terminals 9 and 3
During the startup sequence, terminals 9 and 6 carry voltage and may not be used
as auxiliary terminals
Connect the load controller of two-stage burners to terminal 5 in series with BV2
It is important that signal transmission takes place with the smallest possible
losses:
The cable length may not exceed 20 m
The detector line may not be run together with other conductors in the same cable
since line capacitance reduces the magnitude of the flame signal
The insulation resistance between the ionization electrode and ground must be a
minimum of 50 M, even after a large number of operating hours.
Prerequisite for this is not only high quality heat-resistant insulation of the electrode
cable, but also of the ionization electrode itself (ceramic holder!)
A soiled ionization electrode holder offers favourable conditions for surface leakage
currents which reduce the magnitude of the flame signal
The burner (acting as the counter-electrode) must be correctly earthed, or else no
ionization current will flow
Earthing the boiler alone does not suffice!
In networks with unearthed neutral, use RC unit 4 668 9066 0.
Live, neutral and central point conductors may not be incorrectly connected to terminals 1 and 2 of the burner control, or else no flame signal will be generated
Commissioning and maintenance work must be carried out by qualified staff
When commissioning the plant, when doing maintenance work, or after longer off
periods, perform the following safety checks:
Commissioning notes
a)
b)
Burner startup with no flame signal; for that purpose, cut the
Lockout at the
connection between burner control and ionization electrode
end of TSA
prior to burner startup and maintain this status
Burner operation with simulated flame failure during opera- Repetition
tion; for that purpose, cut the connection between burner control and ionization electrode during burner operation
3/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Mechanical design
The gas burner controls are of plug-in design, suitable for installation in any position on
burners, in control cabinets or on control panels.
LGA...
The housing is made of impact-proof, heat-resistant plastic and accommodates:
The thermal sequencing device (ambient temperature-compensated) acting on a
multiple snap action switching system
The flame signal amplifier with the flame relay, and
The lockout warning lamp and the lockout reset button (splash-proof)
AGK11 plug-in base
Refer to data sheet 7201.
Undervoltage detection
In the event of undervoltage (below approximately AC 165 V), an electronic circuit ensures that the burner control will prevent burner startup.
Only with the
LGA63.191A27
Undervoltage threshold: AC 178 V 10 V
TSA: smaller tolerance band
Flame signal amplifier: higher sensitivity, for typical applications with pilot flames
Type summary
The type references given in the table refer to burner controls with no base and no
accessories.
Burner control with under-
AC 220...240 V
LGA41.173A27
voltage detection
AC 100...110 V
LGA41.153B27
LGA52.150B27
LGA52.171B27
LGA52.191B27
LGA63.191A27
---
---
LGA52.150B17
---
---
---
Connection facility for auxiliary fan )
---
---
Connection facility for air pressure monitor
---
---
Control outputs for gas valves
Reversed polarity protection
1)
Auxiliary fan not monitored to EN 298
Ordering
Gas burner control without plug-in base
refer to Type summary
Plug-in base
(refer to data sheet 7201)
AGK11
Cable gland holder
(refer to data sheet 7201)
AGK65
Cable holder
(refer to data sheet 7201)
AGK66
Cable holder
(refer to data sheet 7201)
AGK67...
Pedestal (empty housing)
For increasing the height of the LGA... (62.5 mm) to that of the LFI1...
or LFI5... (90 mm)
AGK21
Adapter for replacing LFI1... by LGA...
KF8828
Adapter for replacing LFI5... by LGA...
KF8829
RC unit for the supervision of ionization currents in networks with non-earthed neutral
ARC 4 668 9066 0
4/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Technical data
General unit data
Environmental
conditions
Mains voltage
Mains frequency
Power consumption
Input current at terminal 1
Terminal rating
Terminals 4 and 8
Terminals 6, 7 and 9
Terminals 5 and 10
Primary fuse
Degree of protection
Mounting orientation
Weight
Without plug-in base
With plug-in base
Transport
Climatic conditions
Temperature range
Humidity
Mechanical conditions
Operation
Climatic conditions
Temperature range
AC 220 V 15 %...AC 240 V +10 %
AC 100 V 15 %...AC 110 V +10 %
50...60 Hz 6 %
3 VA
max. 5 A
max. 4 A
max. 2 A
max. 1 A
max. 10 A (slow)
IP 40
optional
approx. 180 g
approx. 260 g
IEC 721-3-2
class 2K2
-50...+60 C
< 95 % r.h.
class 2M2
IEC 721-3-3
class 3K5
0...+60 C
for LGA41.173A27 and LGA52.171B27:
-20...+60 C
Humidity
< 95 % r.h.
Condensation, formation of ice and ingress of water are not permitted!
CE conformity
According to the directives of the European Union
Electromagnetic compatibility EMC
89 / 336 EEC incl. 92 / 31 EEC
Directives for gas-fired appliances
90 / 396 EEC
Flame rectification probe
Voltage between ionization electrode and
ground
Required detector current
Possible detector current
Detector line length
Required insulation resistance between
ionization electrode with its cable and
ground
Identification code to EN 298
AMCLXN
ATCLXN
mains voltage
min. 2 A
max. approx. 100 A
max. 20 m (separate cable)
min. 50 M
single-stage
two-stage
5/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Function
Control sequence
(times in seconds) 1)
AC 220...240 V
LGA41.173A27
LGA41.153B27
LGA52.150B27
LGA52.171B27
LGA52.191B27
LGA63.191A27
AC 100...110 V
---
---
LGA52.150B17
---
---
---
t1
Pre-purging with auxiliary fan
15
10
approx. 13
approx. 13
approx. 13
approx. 13
t3
Pre-ignition time
15
10
---
---
---
---
t3
Ignition time from start of TSA
---
---
max. 5
4.5...7.5
7...10
max. 10
TSA
Ignition safety time
10
4.5...7.5
7...10
10
TSAmax.
Max. ignition safety time
20
10
10
20
20
20
t3n
Ignition after flame establishment
max. 2
max. 1
---
---
---
---
t4
Interval BV1 BV2
approx. 13
approx. 18
approx. 18
approx. 13
approx. 23
approx. 23
) All times specified are valid for AC 220 V and AC 110 V respectively
For AC 240 V operation, the above times must be multiplied by 0.7
Control sequence in the
event of fault
Erroneous flame signal during t1
Lockout ) prior to the release of gas
Lockout ) prior to ignition and the
or t3
release of gas
No flame on completion of TSA
Lockout )
Lockout )
Flame failure during operation
Repetition
Repetition
No air pressure signal during t1
--No start
Air pressure failure during operation
--Shutdown
) After lockout, the burner control can be reset after about 60...90 seconds
Flame supervision with
ionization electrode
The conductivity and the rectifying effect of hot flame gases are used for flame supervision. For this purpose, an AC voltage is applied to the ionization electrode which projects into the flame.
The current that flows in the presence of a flame (ionization current) generates the
flame signal which is then fed to the input of the flame signal amplifier.
The amplifier is designed such that it only responds to the DC current component of the
flame signal, thus ensuring that a short-circuit between ionization electrode and ground
cannot simulate a flame signal (since in that case, an AC current would flow).
6/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Internal diagram
LGA41...
When the switch-on command is given, power is supplied to both the ignition transformer and the heating coil of the bimetal sequencing device.
The bimetal bends and pushes contact set c, d, e towards f.
On completion of the pre-ignition time, the system tilts so that e - f closes and f - g
opens.
Contacts c - d still remain closed (c resting on d).
On flame establishment, the flame relay is energized, latching mechanically e - f in
the position now assumed.
The relay also closes contact f and, at the same time, opens c - d, so that the
ignition transformer and the bimetal heating element will be switched off.
Then, d slowly returns to its starting position, also catching g.
When tilting back, g - f closes, so that the main gas valve BV2 will be energized.
If no flame signal is generated, the flame relay does not open c - d, so that the
bimetal will continue to be heated.
The bimetal thus continues to bend until tilting it actuates contact tz2: Lockout.
In the event of an erroneous premature flame signal, the flame relay by means of its
latch - prevents e - f from making, which means no release of gas.
TZ, however, remains under voltage, so that the bimetal continues to bend until,
eventually, lockout is initiated by tz2.
LGA41...
tz2
L1
EK
tz1
c d
a b
X Y Z
f g
FR
fr
TZ
1 2
SB
10
11
7 6
12
BV1
BV2
FE
AL
L
N
Legend
AL
7418i02/0200
Fault status signal
SB
BV...
Fuel valve
TZ
EK
Lockout reset button
FE
Ionization electrode
FR
Flame relay
L1
Built-in lockout warning lamp
Thermostat or pressurestat
Safety limit thermostat
Electro-thermal timer
(bimetal system) with contacts tz
Thermal reset limit thermostat or manual
reset safety limit thermostat
Ignition transformer
7/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Internal diagram
LGA52... / LGA63...
When the switch-on command is given, the auxiliary fan starts to run.
When the air pressure monitor closes its contact, the heating coil of the bimetal sequencing device is energized and the bimetal pushes contact set c, d, e towards f
(thereby opening f - g).
On completion of the pre-purge time, e - f is closed so that both the gas valve BV1
and the ignition transformer receive voltage: the safety time starts.
On flame establishment, the flame relay latches mechanically e - f, pushes c back
at the same time and opens fr.
The ignition transformer is thus switched off and the heating coil de-energized, so that
d can revert to its starting position.
When tilting back, g - f closes, so that the main gas valve BV2 receives voltage.
If no flame signal is generated, the flame relay does not open c - d, so that the
bimetal will continue to be heated.
The bimetal thus continues to bend until tilting it actuates contact tz2: Lockout
In the event of an erroneous premature flame signal, the flame relay by means of its
latch - prevents e - f from making, which means no release of gas.
TZ, however, remains under voltage, so that the bimetal continues to bend until,
eventually, lockout is initiated by tz2.
LGA52... / 63...
tz1
tz2
L1
EK
ab
c d
X Y Z
f g
FR
fr
TZ
1 2
SB
10
11
LP
BV1
BV2
12
FE
AL
1)
L
N
Legend
7418i01/0200
AL
Fault status signal
Thermostat or pressurestat
BV...
Fuel valve
SB
Safety limit thermostat
EK
Lockout reset button
TZ
FE
Ionization electrode
FR
Flame relay
L1
Built-in lockout warning lamp
Electro-thermal timer
(bimetal system) with contacts tz
Thermal reset limit thermostat or manual
reset safety limit thermostat
LP
Air pressure monitor
Ignition transformer
Auxiliary fan
1)
Not monitored to EN 298
8/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Connection diagram
Control sequence
LGA41...
LGA41...
FR
1
11
10
A
SB
R/W
1
t3n
t3
12
SB
W
FE
Z
BV1
BV2
TSA
4
BV1
t4
AL
BV2
12
FS
L
N
7418f01/0200
7418a04/0200
LGA52... / LGA63...
LGA52... / 63...
FR
1
SB
W
R
11
LP
11
FE
1)
BV1
BV2
12
10
LP
M
SB
R/W
AL
L
N
6
7418a05/0200
t1
t4
t3
Z
TSA
BV1
BV2
5
12
FS
Legend
AL
Fault status signal
7418f02/0200
Auxiliary fan
BV...
Fuel valve
Thermostat or pressurestat
FE
Ionization electrode
SB
Safety limit thermostat
FR
Flame relay
Thermal reset limit thermostat or manual
FS
Flame signal
LP
Air pressure monitor
Ignition transformer
Required input signals
1)
Not monitored to EN 298
reset safety limit thermostat
Burner controls output signals
Commencement of startup sequence
Operating position
Time of flame establishment
Controlled shutdown by R
t1
Pre-purging with auxiliary fan
t3n
Ignition on flame establishment
t3
Pre-ignition time
t4
Interval BV1 BV2
t3
Ignition time from the start of TSA
TSA
Ignition safety time
9/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
Dimensions
Dimensions in mm
7418m01/0200
62,5
5,5
LGA...
25
25
41,5
88
91
LGA... with AGK11 plug-in base and AGK65
7418m02/0200
22
xxxxxxxxxx
62,5
47
cable gland holder
AGK11 plug-in base
2
10
11
12
31
16
,2
5,
4,5
23,5
32
17
A
B
10,5
C
24
30
24
30
Plug-in base with screw terminals.
Hatched: position of insertable cable gland holder or cable holder.
A: holes for the fixing screws
B: holes for cable entry
31 / 32: auxiliary terminals
N: neutral terminals, connected to neutral input (terminal 2)
Underneath: 4 earth terminals, joining in a lug for earthing the burner
Also refer to data sheet 7201.
Mandatory:
Earthing lug C and fixing screws in A must be connected to burner ground (using a
metric screw with a lockwasher or similar).
2000 Landis & Staefa Produktion GmbH
10/10
Siemens Building Technologies
Landis & Staefa Division
CC1N7418en
27.06.2000
