7 761

January 1997

FM739 LEC1...
Control Unit Series 02

Control unit for double or multi-flame supervision of oil, gas or forced draught
oil/gas burners of any fuel throughput (for continuous or intermittent operation).

Use The LEC1... control unit is designed for the fully automatic start-up and supervision of
those forced draught burners with which the flame supervision should or must be carried
out by separate flame safeguards, e.g. with

- Dual supervision (of the main flame or of the pilot and main flame by means of two
identical or different detectors).
- Supervision of forced draught oil/gas burners (with different types of detectors
according to selected operating mode).
- Multi-flame supervision (i.e. central and simultaneous control of the start-up and
supervision program for several burners, the flames of which, however, must be
individually supervised by one or two flame safeguards each).

The following flame safeguards are available:

LAE10... for the supervision of oil burners with active selenium photocell sensor RAR... in
intermittent operation.

LFE10... for the supervision by means of ionization field (gas burner) or with UV-
detectors QRA... (gas, oil or dual fuel burners, with or without ignition spark supervision)
in intermittent operation.

LFE50... for the supervision with UV-detectors QRA50.../51... (gas, oil or dual fuel
burners) in intermittent or continuous operation.

All devices comply with the relevant European standards for oil, gas and forced draught
burners of any fuel throughput.

The LEC1... can control the following burner plant components: fan motor, flue gas fan,
air damper, ignition transformer, one to three fuel valves, the load controller and an
external fault signaling device.

Grafikname:
Erstellt in:
CC1N7761E Erstellt am:
Construction of the The control unit LEC1... as well as the flame safeguards LAE10... and LFE10... are of
Control Unit and the plug-in design and are suitable for the mounting in any position at the burner, on control
panels and in control cabinets. The spacious terminal bases and the housings are made
Flame Safeguards
of impact proof and heat-resistant plastic. The switching mechanism of the unit driven by
a synchronous motor, its relays as well as all other switching, control and adjusting
elements are mounted on solid printed circuit boards.

Operation The following description of the mode of operation refers to the start-up and supervision
of one single burner.

With multi-flame supervision all of the burners connected to the control unit are put into
operation and supervised simultaneously in the same manner. A defect leading to a lock-
out at one of the burners therefore results in the shutdown of all burners. The prerequisite
for the immediate restart of the non-defective burners is the bridging of the flame
safeguard of the defective burner by means of an operating switch. This switch must
simultaneously interrupt all control lines to the ignition transformer and the fuel valves. For
connection examples please refer to data sheet 7781.

Prerequisites for the The burner is started only if:

burner start-up
- the switching mechanism of the control unit is in its start position
- the control unit is not in lock-out position, e.g. with defective UV-tube
- the contacts of all the control and safety devices in the control loop between
terminal 8 and 9 are closed
- the air pressure monitor does not indicate any air pressure

Defects in the flame safeguard or in the control unit prevent the start or lead to a lock-out
during the start-up.

Important If the air damper is not controlled by the control unit, terminal 20, 21 and 22 must be
interconnected.

Program sequence First the fan motor is switched on via terminal 3 and the air damper actuator is driven via
during burner start-up terminal 22. As soon as the air damper has reached its fully open position, the switching
mechanism of the unit starts its run - the prepurge time begins. The minimum air pressure
set at the air pressure monitor must be reached within 10 s (or 7 s in operation with post-
purge) and must be maintained until the controlled shutdown, otherwise lockout occurs. A
flame signal during the prepurge time also leads to a lockout. On completion of the set
prepurge time the air damper receives the control command to return to the minimum air
position. During the air damper’s closing time the switching mechanism remains
stationary. As soon as the signal contact for the minimum butterfly position is operated by
the air damper actuator, the switching mechanism starts again and now controls the
program sequence which can no longer be influenced externally:

- Pre-ignition (3 s)
- Release of the 1st fuel valve via terminal 5 (the fuel valve of a pilot burner which must
be closed on completion of the 2nd safety time must, however, be connected to
terminal 10)
- Programming of the set safety time. If no flame is established during this time, lockout
occurs (always with interlocking of the control unit)
- Following an interval of 11 s after the release of the 1st valve, the 2nd fuel valve is
released
- The pilot burner, if connected to terminal 10, is switched off
- The load controller is switched on after a further interval of 12 s. Now the burner has
reached its operating position. From now on the load controller controls the burner
capacity by either increasing or decreasing the fuel throughput and the air volume
depending on the heat demand (fuel/air ratio control). This can be carried out in stages,
i.e. by means of thermostats or continuously (modulating) by using a continuous
controller.

The loss of flame during operation always leads to burner lockout.

2 CC1N7761E
Burner start-up with In principle the program sequence is the same as with burner start-up without ignition
ignition spark spark supervision. Exceptions:
supervision
- If the flame safeguard does not receive any input signal during the short pre-ignition
time (UL2 on position «Short pre-ignition»), lockout occurs before any gas is released,
i.e. safety time t2 = 0 s.
- With ignition spark supervision the safety time for the pilot burner can only be adjusted
between 0 ... 6 s (in the time diagram of the switching mechanism: t2z).

Control program Controlled shutdown is carried out as soon as one control or supervision device in the
following a controlled control loop between terminal 8 and 9 open its contact, i.e. the fuel valves are closed
shutdown immediately. The switching mechanism starts again and now programs the post-purge, if
necessary. On completion of the post-purge time the switching mechanism has again
reached its start position in which it remains until the next switching on command is
received.

The flame supervision restarts again during the post-purge time; therefore every flame
signal during this time leads to a lockout.

Control program After actuation of the built-in or external reset button the switching mechanism runs
following lockout reset through to its start position. The only burner plant component which is operated during
this time is a fan motor connected to terminal 17. As the limit thermostat or pressurestat
normally continues to call for heat, the unit immediately initiates a restart as soon as it has
reached its start position.

Program Indicator The program indicator continuously shows the respective phase of the burner start-up
sequence. The letters correspond to those of the switching mechanism diagram next to
the viewing window. The figures indicate the remaining pre-purge time. If lockout occurs
the switching mechanism and the program indicator stop and by this means determine
the operating phase during which the lockout occurred.

Reading the program Í Remaining pre-purge time approx. 35 s

indicator
Valve 2 at terminal 7 is opened Î

CC1N7761E 3
Technical Data
Control unit LEC1
Mains voltage AC 220 V -15%...AC 240 V +10% Radio interference protection
AC 100 V -15%...AC 110 V +10% N according to VDE0875

Mains frequency 50 Hz -6%...60 Hz +6% Max. permissible load on the control outputs
Unit fuse, built-in T6,3H250V − per terminal 4A
External fuse 10 A max., slow − in total 5A

Consumption Degree of protection IP40

− during start 8 VA Mounting position optional
− during operation 5 VA Cable gland Pg11
Weight approx. 2 kg

Identification code according to EN 298

FBLLBN

Environmental conditions: CE-Conformity

- Transport IEC721-3-2 According to the directives of the European Community
Climatic conditions class 2K2 Electromagnetic compatibility EMC
Temperature -50...+60 °C 89/336 EWG includ. 92/31 EWG
Humidity < 95 % r.F. Gas appliance directive 90/396 EWG
Mechanical conditions class 2M2 Interfering emissions EN 50081-1
- Operation IEC721-3-3 Immunity against disturbances EN 50082-2
Climatic conditions class 3K5
Temperature -20...+60 °C
Humidity < 95 % r.F.
Condensation, formation of ice and influence of water are not permitted.

Flame supervision3) LFE10... LFE10... LAE10...

Series 02 Series 02 Series 02
ionization field UV-cell selenium cell

Minimum required detector current in µA

− with AC 100 V and AC 220 V 8 150 8 min.
− with AC 110 V and AC 240 V 9 200 8 min.
Max. possible detector current in µA approx. 100 approx. 650 approx. 25

Detectors Permissible connecting cable length 20 m1) 20 m1) 20 m2)

Permissible ambient temperature − 60°C 60°C
1
) In case of larger distances use low capacitance cable, e.g. one-core cable (total 2 nF max.)
2
) Detector cables must always be laid separately, the selenium photocell RAR8 must be used in case of
larger distances
3
) For information on LFE50... please refer to data sheet 7783

Type Summary and

Ordering Type/Ordering Supply voltage Factory settings for
reference (V) Hz t1 (s) t2 (s) t9 (s)
LEC1/8851 AC 220...240 50 60 2 2
LEC1/8853 AC 220...240 50 30 2 2
LEC1/8866 AC 100...110 50 30 2 2
LEC1/8867 AC 100...110 60 30 2 2
LEC1/8868 AC 220...240 60 30 2 2
LEC1/8892 AC 220...240 50 60 5 5
LEC1/8906 AC 220...240 50 30 2 5

The control unit is delivered without terminal baseplate. The latter must be ordered
separately using the following type reference: AGG41041713 (EC)

For flame safeguards LAE10... and LFE10... as well as the appropriate detectors, please
refer to data sheet 7781.

4 CC1N7761E
Basic Diagram LEC1

LAE10... and LFE10...

Attention: When using the UV-detector QRA... terminal 10 must be connected to earth!

CC1N7761E 5
 AS Unit fuse L2 Lockout warning device, external
Legend AR Working relay with contacts «ar...» L3 Signal lamp for the flame indication
for the entire data sheet BR Lockout relay with contacts «br...» LK Air damper actuator with limit or auxiliary
BS1 Operating switch switches
BS2 Operating mode selector switch (see also «Connection examples»)
BV... Fuel valve a = actuator runs into position «Open»
(BV...) Fuel valve for a pilot burner which is switched (maximum air volume)
off on completion of the 2nd safety time z = actuator runs into position «Closed»
c... Fan contactor with contacts «c...» (minimum air volume)
d... Auxiliary relay with contacts «d...» LP Air pressure monitor
e... Thermal overload fuse M... Fan
EK1 Reset button at the unit NTC High-temperature conductor (delay unit)
EK2 Remote reset button OV... Oil valve
FE Flame detector electrode Q Temperature or pressure detector
FR Flame relay QRA... UV-detector
FW Contacts of the flame safeguards LAE10..., R... Thermostat or pressurestat
LFE10... or LFE50... RAR... Selenium photocell detector
GP Gas pressure monitor RV Control valve
GV... Gas valve SB Safety limiter
H Main isolator SM Synchronous motor of the switching
HR1 Auxiliary relay with contacts «hr11 and hr12» mechanism
HR2 Auxiliary relay with contact «hr21» SQ... Type reference of air damper actuator
HR3 Auxiliary relay for flame detector or flame UL1 Operating switch for motor of the switching
simulation test mechanism
L1 Lockout warning device, built-in UL2 Changeover link for
«Short/long pre-ignition time»
UL3 Changeover link for «STOP» or «Run» of
the sequence mechanism after a lockout
W Limit thermostat or pressure monitor
Z Ignition transformer

* Do not press EK longer than 10 s

Time Diagram of the

Switching Mechanism
Switching times I 81
a
II b
t2 79

III
t2z
a
IV b
67 t4 t9
90
V t3´ t5
a
VI b
93
t3
VII 70
a
VIII b
3
a
IX b
t7
X t10 10

XI 66
a
XII b
t1
a
XIII b
63
t11 7761d01/0696
t12
t8 t6
T
T 120 s Running time of the switching mechanism
t1 8...63 s Pre-purge time, adjustable
t2 0...9 s 1st safety time, adjustable (set to 0 s with ignition spark supervision)
t2z 0...6 s Safety time for the pilot burner in case of burner start-up with
ignition spark supervision
t3 t11 + t1 + t12 + 7 s Pre-ignition time «Long» (during the whole pre-purge)
t3’ 3s Pre-ignition time «Short»
t4 11 s Interval between release of the 1st and 2nd fuel valve
t5 12 s Interval between release of the 2nd and 3rd fuel valve or the load
controller
t6 T- (30 + t1) Post-purge time
t7 3s Delay time
t8 t1 + 30 + t11 + t12 Total start-up time
t9 0...9 s 2nd safety time with interrupted pilot burner
t10 10 s Bridging time (set time for the air pressure control)
t11, t12 optional Opening or closing time of the air damper
Maximum permissible after-burn time
(counted as of the beginning of t6) 7s
For the factory setting of the different types, please refer to the type summary.

6 CC1N7761E
Specific Features The construction, control program and adjustment facilities of the unit allow its almost
unlimited use in burner plants of any size and type of construction, be it expanding flame
or interrupted pilot burners, permanently operating or any other special burners.

With respect to the - Prepurge time adjustable between 8 and 63 s

application - Operation at option with or without post-purge
- Fully automatic control of the air damper, with optional running time of the damper
actuator
- Air pressure check can be combined with functional control of the air pressure monitor
prior to the start
- Ignition at option: direct ignition, with pilot burner as well as with or without ignition spark
supervision
- Pre-ignition time adjustable to «Long» (during the pre-purge time) or «Short» (3 s, e.g.
for forced draught gas burners)
- 1st and 2nd safety time adjustable between 0 and 9 s
- Automatic test of flame safeguards and flame detectors during burner-off periods and
the purge times (with lockout if a faulty flame signals occurs)
- Semi-automatic burner start and operation possible

With respect to - Optional mounting location and position of the control unit
mounting and - Large space for connection in terminal base
installation - Additional 4 terminals each for earth and neutral conductors as well as 4 auxiliary
terminals

With respect to - Continuous indication of the program sequence in the viewing window of the unit cover.
commissioning and *
trouble shooting - The motor of the switching mechanism can be switched off (simplifies burner
adjustment)
- Cam shaft can be rotated by hand
- Electric remote lockout reset facility

For adjustment instructions please refer to «Adjustment facilities at the unit»

* It is, however, also possible to program the unit by means of a changeover link (UL3) in
such a way that the programming mechanism does not stop in case of a lock-out, but
that it runs through to the end of the program. The only component that remains under
voltage during that time is a fan for the post-purge which is connected to terminal 17.

Warning Notes • In the area covered by DIN assembly and installation must comply with the
requirements of the VDE, especially with the DIN/VDE standards 0100 and 0722!
• The electrical wiring must be made in accordance with national and local
standards.
• LEC1... is a safety device! The loosening of the securing screws as well as any
changing of the factory setting must therefore be carried out by authorized
persons only!
• Check wiring carefully before putting the unit into operation!
• The LEC1 must be completely isolated from the mains before performing any
work on it!
• Check all safety functions when putting the unit into operation or after having
replaced any fuses!
• Ensure protection against contact at the unit and at all electrical connections by
appropriate mounting!
• Electromagnetic emissions must be checked from an application point of view!
• Condensation and any influence of humidity must be avoided!

CC1N7761E 7
Adjustment Facilities
at the Unit
General instructions - Isolate the unit from the mains prior to any adjustment
- Loosen all 6 retaining screws and only remove the unit cover
- The numbering of the switching cams always starts from the motor
- The cam shaft can be turned into any position by hand (clockwise direction of rotation
as seen from the motor)

Adjustment elements UL1 ON/OFF switch for the motor of the N5 Cam 5, adjustable (2nd safety time)
switching mechanism N7 Cam 7, fixed
N1 Cam 1, fixed N8 Cam 8, adjustable (prepurge time)
N2, N3 Cam 2 and 3, adjustable (1st safety time) PA Program indicator
N4 Cam 4, fixed

Important LEC1... is a safety device! The loosening of the securing screws as well as any
modification of the factory setting may therefore be carried out by authorized
persons only!

On the rear side of the baseplate:

UL2 Changeover link for «Short/long pre-ignition time», in position «Short pre-ignition» locked with varnish
UL3 Changeover link for «STOP» of the control sequence following a lockout or «Restart». Only the fan for the
post-purge connected to terminal 17 remains under voltage.

Adjustment of the pre- C «Long pre-ignition time» (during the prepurge)

D «Short pre-ignition time» (3 s, factory setting)
ignition time
Loosen screw before carrying out the adjustment and tighten it
carefully afterwards!

8 CC1N7761E
Adjustment of the - Loosen the securing screw of the red cam 8
prepurge time - Turn the cam shaft by hand until the required pre-purge time is indicated next to the
index notch on the carrier of the switching mechanism
- Hold the cam shaft firmly and rotate cam 8 until the contact tappet operated by it just
jumps out or the cam strikes this tappet
- Carefully tighten the securing screw of the cam and check the adjusted time for
accuracy. The set time is also visible in the viewing window, if the unit is in its start
position.

The adjustments of the mark of the red cam N8 to the graduation marks of the black
cam N7 result in the prepurge times given in the following table.

Cam 8 adjusted to...

...cam 7, graduation mark
I t1 = 8 s
II 18 s
III 28 s
Adjustment at stop 63 s
Factory setting ca. 30 s
or 60 s

Adjustment of the safety The safety times are adjusted by setting the red cams of the switching mechanism. Their
times time marks serve as setting aid. After the adjustment the securing screws of the cams
must be tightened very carefully to make any unintentional readjustment impossible.

1st safety time t2 (operation without ignition spark supervision)

- Loosen the securing screws of cams 2 and 3

- Hold cam 1 firmly and align the setting mark of cam 2 with the according time mark I of
cam 1 (see picture and table, intermediate positions possible). Lock cam 2.
- Rotate cam 3 in such a way that its setting mark is set against the lower stop of cam 2.
Lock cam 3.
- Check the adjusted safety time and set the new value on the rating plate of the unit
cover (adjustment slot on the rear side of the cover).

Cam 2 adjusted to ...

...cam 1, time mark I t2 = 0 s
II = 4,5 s
III =9s
Factory setting <2s

CC1N7761E 9
1st safety time t2z (operation with ignition spark supervision)

- Loosen the securing screws of cams 2 and 3

- Hold cam 1 firmly, set the setting mark of cam 2 to the time mark I of cam 1 and lock
cam 2.
- Hold cam 2 firmly, set the setting mark of cam 3 to the required time and lock cam 3
(see photo and table).
- Check adjusted safety time

Cam 3 adjusted to...

...stop in the arrow direction t2z = 0 s
...the other stop 6s
Factory setting 0s

2nd safety time t9 - Loosen the securing screw of cam 5 and align its setting mark to the according time
marks of cam 4 (see photo and table, intermediate settings possible).

Cam 5 adjusted to ...

...cam 4, time mark I t9 = 0 s
II = 4,5 s
III =9s
Factory setting <2s

10 CC1N7761E
Connection Examples For connection examples for the flame supervision with DETACTOGYR LFE50... see
and Time Diagrams data sheet 7783.

Double or multi-flame Start-up with long pre-ignition (t3) and supervised air damper control. Air pressure
supervision of oil supervision from the start to the controlled shutdown. No load control. Necessary flame
burners safeguards: type LAE10... with selenium photocell detector RAR...

LEC1... UL.2

16 1 2 13 14 15 12 19 18 8 9 4 3 22 21 20 17 6 5 7 11
* *
FW
3 4
e2 d1
SB d1
EK2
6
H c1 e1 d1
7 5
M1 M2 c2
OV2
M M FW 4 c1
3
1 2 12 11
6 LP
c1 c2 P T a z
7 5
e1 e2 R1 OV1 OV3
(LAE10...) M
T
N
LK Z
W
L2

P N 7761a03/0696
(R) (Mp)

A B C D E
LK
M
22
Luft
21

Öl 21/d1
18/c1/d1
OV3
20

LK"a"
OV2

7761a04/0696 7761d03/0696
LK"z"
OV1
t11 t1 t12 t11 tn t6 t12

Air damper control, detailed

Important In case of burners without air damper or with an air damper not controlled by the control unit, terminals 20, 21 and
22 must be interconnected; the path 18-c1-21 of the circuit, however, must be omitted!

* Connection is dropped with the use of an air pressure monitor LP

A B C D E F G H I K L
t8 tn t6 t6
M1 Kl.3
t7 t7
M2 17
t11 t1 t12 t1
LK 22/21
t2 t2
Z 6
t3 t3
OV1 5
t4 t4
OV2 7
t5 t5
OV3 11

FW 13/14

L2 12

7761d02/0696

CC1N7761E 11
Double or multi-flame Start-up with short pre-ignition (3 s) and supervised air damper control. No load control.
supervision of gas Necessary flame safeguards: type LFE10... with UV-detectors QRA... or ionization field.
burners (expanding
flame burner)

A B C D E
LK
M 22
Luft
21

Gas 21/d1
18/c1/d1
GV3
20

LK"a"
GV2

7761a06/0696 7761d04/0696
LK"z"
GV1
t11 t1 t12 t11 tn t6 t12

Air damper control, detailed

Important In case of burners without air damper or with an air damper not controlled by the control unit, terminals 20, 21 and
22 must be interconnected; the path 18-c1-21 of the circuit, however, must be omitted!

A B C D E F G H I K L
t8 tn t6 t6
M1 Kl.3
t7 t7
M2 17
t11 t1 t12 t1
LK 22/21
t2 t2
Z 6
t3´ t3´
GV1 5
t4 t4
GV2 7
t5 t5
GV3 11

FW 13/14

L2 12

7761d05/0696

Legend A Start G-H Operation

A-B Normal start-up H Loss of flame
for the switching diagram B-C Operation H-I Lockout
C Controlled shutdown I Reset
C-D Post-purge I-K Run into start position
D-E Closing of the air damper K Restart
E-F Burner off-period K-L Start-up
F Restart L Operation
F-G Start-up

12 CC1N7761E
Double or multi-flame Start-up with short pre-ignition (3 s) and supervised air damper control. Control of the 2nd
supervision of burners output stage via on/off controller (R2). Necessary flame safeguards: type LFE10... with
for selectable operation UV-detectors QRA...
with oil or gas
(expanding flame burner)

Operating switch BS1

OV2 I Full load

Öl II Stop
III Partial load
IV Automatic control
OV1

Operating mode selector switch BS2

OV3 I Gas
Luft M LK
II Off
III Oil

GV1

Gas

7761a09/0696
GV2

GV3

CC1N7761E 13
Double or multi-flame including supervised air damper control. Necessary flame safeguard:
supervision of For oil: LAE10... with active selenium photocell detectors RAR...
modulating burners For gas: LFE10... with UV-detectors QRA... or ionization field
For oil/gas: LFE10... with UV-detectors QRA...

Luft M LK Operating switch BS1

BV1 SQ... I Full load

7761a11/0696 II Stop
III Partial load
Brennstoff IV Automatic control
RV

Burners that are designed for continuous adjustment of the burner capacity (modulating
burners) require, in addition to the standard burner equipment, the devices of the
temperature or pressure control circuit, e.g.
1 Continuous controller, e.g. POLYGYR RWF32 1 Auxiliary relay d1
1 Operating switch BS 1 Control valve or similar for the adjustment
1 Temperature or pressure detector QA.../QB... of the fuel volume RV
1 Actuator for the control of the air 1 Setting unit for remote setting, if necessary FZA...
damper and the fuel throughput
(fuel/air ratio control) SQ...

* Omitted with oil burners

** Recommended for oil burners, if the oil pump is not coupled to the fan motor

18 8 9
Control for semi-
automatic operating
mode T

L W
N (Mp)

7761a07/0696
I 0

This circuit is used when fully automatic operation is not required due to certain reasons
(e.g. with industrial burners). The burner is started by actuation of the impulse contact I;
the burner is shut down by either pressing the circuit-breaking contact 0 or by operating
the limit thermostat.

14 CC1N7761E
Dimensions Dimensions in mm

LEC1

Baseplate
AGG 41041713 (EC)

Important: To remove the control unit from the plug-in baseplate, only the 4 screws A must be loosened.
To remove the unit cover the 2 screws B also have to be loosened.
C: Elongated holes for fixing the baseplate.
EK: Reset button
SG: Viewing window

 Landis & Gyr Deutschland Produktion GmbH

CC1N7761E Subject to modification 15
January 13, 1997