7

Burner Controls

435

LGB...

Burner controls for the supervision of 1- or 2-stage gas or gas / oil burners of
small to medium capacity (typically up to 350 kW), with or without fan, in intermittent operation.
The LGB... and this Data Sheet are intended for use by OEMs which integrate the
burner controls in their products!
Use
The LGB... burner controls are used for the startup and supervision of 1- or 2-stage gas
or gas / oil burners in intermittent operation.
Depending on the type of burner control used, the flame is supervised either by an
ionization probe, a blue-flame detector QRC1... for forced draft gas / oil burners, or a
UV detector QRA... (with auxiliary unit AGQ1...A27).
In connection with the respective adapters, the LGB... burner controls replace their
predecessor types LFI7... and LFM1... (also refer to Replacement types under Ordering).
-

CC1N7435en
07.07.2004

Automatic forced draft burners for gaseous fuels to EN 676

Gas burner controls to EN 298
Undervoltage detection
Air pressure supervision with function check of the air pressure switch during
startup and operation
Electrical remote reset facility
LGB41... for use with atmospheric gas burners

Siemens Building Technologies

HVAC Products

Warning notes
To avoid injury to persons, damage to property or the environment, the following
warning notes should be observed!
Do not to open, interfere with or modify the unit!

All activities (mounting, installation and service work, etc.) must be performed by
qualified staff

Before performing any wiring changes in the connection area of the LGB..., completely
isolate the burner control from the mains supply (all-polar disconnection)
Ensure protection against electric shock hazard by providing adequate protection for the
burner controls connection terminals

Check to ensure that wiring is in an orderly state

Press the lockout reset button only manually (apply a force of no more than 10 N),
without using any tools or pointed objects

Fall or shock can adversely affect the safety functions. Such units must not be put into
operation, even if they do not exhibit any damage

Ensure that the relevant national safety regulations are complied with

Always run the ignition cables separate from the unit and other cables while observing
the greatest possible distance

Do not mix up live and neutral conductors

Mounting notes

Installation notes

Install switches, fuses, earthing, etc., in compliance with local regulations

Ensure that the maximum permissible current ratings will not be exceeded (refer to
Technical data)
Do not feed external mains voltage to the control outputs of the unit. When testing the
devices controlled by the burner control (fuel valves, etc.), the LGB... must not be connected
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 base with a metric screw and a lockwasher
In the case of burners with no fan, the AGK25 must be connected to terminal 3 as a
burden, or else the burner cannot reliably start
For safety reasons, feed the neutral conductor to the neutral distributor in the plug-in
base, or to terminal 2. Connect the burner components (fan, ignition transformer and
gas valves) as represented in the figure 7435a14, to the neutral distributor as shown
below. The connection between neutral conductor and terminal 2 is prewired in the
base
2

Example

Legend

V2

M
Z

V1

N
7435a14/0601

V...
M
Z

Fuel valve
Fan motor
Ignition transformer

Correct wiring of neutral conductors!

2/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Electrical connection of flame detectors

It is important to achieve practically disturbance- and loss-free signal transmission:
Never run detector cables together with other cables
Line capacitance reduces the magnitude of the flame signal
Use a separate cable
Observe the permissible length of the detector cables (refer to Technical data)
The ionization probe and the ignition electrode are not protected against electric shock
hazard

Locate the high-voltage ignition electrode and the ionization probe such that the ignition
spark cannot arc over to the ionization probe (risk of electrical overloads) and that it
cannot adversely affect the supervision of ionization

With both ionization current and UV supervision, the cable length for flame detection must not exceed 20 m
Insulation resistance
Must be a minimum of 50 M between ionization probe and ground
Soiled detector holders reduce the insulation resistance, thus supporting creepage currents
Prerequisite is not only high-quality heat-resistant insulation of the probes
cable, but also of the ionization probe itself (ceramic holder)
Earth the burner in compliance with the relevant regulations; earthing the boiler
alone does not suffice

The connection diagrams show the burner controls with earthed neutral conductor. In
networks with nonearthed neutral conductor and ionization current supervision, terminal
2 must be connected to the earth conductor via an RC unit (type reference
ARC 4 668 9066 0). It must be made certain that local regulations are complied with
(e.g. protection against electric shock hazard) since AC 230 V / 50 Hz mains voltage
produces peak leakage currents of 2.7 mA

Prior to commissioning, check to ensure that wiring is in an orderly state

When commissioning the plant for the first time or when doing maintenance work,
make the following safety checks:

Commissioning notes

a)

b)

c)

Safety check to be carried out

Burner startup with previously interrupted line to the ionization probe and
flame detector darkened in the case of
QRA... or QRC1...
Burner operation with simulated loss of
flame. For that purpose, cut off the gas
supply (e.g. disconnect the fuel valve
while ensuring protection against electric shock hazard)
Burner operation with simulated air
pressure failure (not with atmospheric
burners)

Anticipated response
Lockout at the end of TSA

Immediate lockout

Immediate lockout

3/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Standards and certificates

Conformity to EEC directives
- Electromagnetic compatibility EMC (immunity)
- Low-voltage directive
- Directive for gas appliances

ISO 9001: 2000

Cert. 00739

ISO 14001: 1996

Cert. 38233

Identification code to EN 298

- LGB21... / LGB22...
- LGB32...
- LGB41...
(BV1 + BV2 or ZBV + BV2)

LGB21.130A17
LGB21.130A27
LGB21.230A27
LGB21.330A27
LGB21.350A17
LGB21.350A27
LGB21.550A27
LGB22.130A27
LGB22.230B27
LGB22.330A17
LGB22.330A27
LGB22.330A270
LGB32.130A27
LGB32.230A17
LGB32.230A27
LGB32.330A17
LGB32.330A27
LGB32.350A17
LGB32.350A27
LGB41.255A27
LGB41.258A17
LGB41.258A27

89 / 336 EEC
90 / 396 EEC
73 / 23 EEC

x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x

F T L L X N with 2-stage operation

F M L L X N with 2-stage operation
A B L L X N with 2-stage operation
A M L L X N with 1-stage operation

x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x

--x
x
x
--x
x
x
x
--x
x
x
--x
x
x
x
x
-------

Service notes

Each time a unit has been replaced, check to ensure that wiring is in an orderly
state. Make the safety check in accordance with section Commissioning notes
Use KF8872 service adapter for short periods of time only

Disposal notes
The unit contains electrical and electronic components and must not be disposed of
together with household waste.
Local and currently valid legislation must be observed.

4/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Mechanical design
The housing is made of impact-proof, heat-resistant and flame-retarding plastic.
It is of plug-in design (measuring 91 x 62 x 63 mm, including the base) and engages
audibly in the base.
The housing accommodates the
programming mechanism with the synchronous motor
electronic flame signal amplifier (ionization) with the flame relay and the other
switching devices
lockout reset button with its integrated fault indication lamp
Type summary
The type references given below apply to LGB... burner controls without plug-in base
and without flame detector. For ordering information on plug-in bases and other accessories, refer to Mechanical design, Ordering, Flame supervision ... and Technical data.
Flame detector

Type reference

Approved in:

tw/s

t1/s

TSA/s

t3n/s

t3/s

t4/s

t9/s

t10/s

6)

ca.

min.

max.

ca.

ca.

ca.

max.

min.

t11/s

t12/s

3)

3)

max.

max.

t20/s
ca.

Burner controls for prepurging with low-fire air volume and control of actuator
Ionization probe (ION)

LGB21.130A27 4)7)

CH, EU, S, SF

2.4

---

---

---

or UV detector QRA... LGB21.230A27 5)

CH, EU, S, SF

15

2.4

---

---

---

38

with AGQ1...A27

LGB21.330A27 5)

CH, EU, H, S, SF

30

2.4

---

---

---

23

LGB21.350A27 5)7)

CH, EU, H, S, SF

30

10

---

---

---

21

LGB21.550A27 5)

AUS, CH, EU

50

10

---

---

---

Burner controls for prepurging with nominal load air volume and control of actuator
Ionization probe (ION)

LGB22.130A27 4)

CH, EU, N, S

2.4

---

12

12

21

or UV detector QRA...

LGB22.230B27 5)

CH, EU, N, S, SF

20

2.4

---

16.5

16.5

with AGQ1...A27

LGB22.330A27 5)7)

AUS, CH, EU, H, N, S, SF

30

2.4

---

12

11

LGB22.330A270 5)8)

EU

30

2.4

---

12

11

Blue-flame detector

LGB32.130A27 4)1)

CH, EU

2.4

---

12

12

21

QRC1...

LGB32.230A27 5)1)

CH, EU

20

2.4

---

12

12

LGB32.330A27 5)

CH, EU

30

2.4

---

12

11

LGB32.350A27 5)

CH, EU

30

4.4

10

---

12

EU

18

---

10

---

---

---

10

18

---

10

---

---

---

10

Burner controls for atmospheric burners

Ionization probe (ION)

LGB41.255A27

or UV detector QRA... LGB41.258A27 2)5)7) CH, EU, H, SF

with AGQ1...A27
Legend

tw

Waiting time

1)

On request

t1

Prepurge time

2)

For atmospheric burners up to 120 kW

TSA

Ignition safety time

3)

Maximum running time available for actuator

t3

Preignition time

4)

Also suited for flash steam generators

t3n

Postignition time

5)

Also suited for stationary direct-fired air heaters

t4

Interval BV1-BV2 or BV1-LR

6)

t9 + reaction time of flame relay

7)

t9

Second safety time (only with LGB41...)

t10

Specified time for air pressure signal

t11

Programmed opening time for actuator SA

t12

Programmed closing time for actuator SA

t20

Interval up to self-shutdown of programming mechanism

Also available for AC 100...110 V; in that case, the last 2

digits read ...17 in place of ...27

8)

Without internal microfuse; must only be used in connection

with external microfuse 6.3 A (slow)!

5/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Ordering
Burner control, without plug-in base

refer to Type summary

Connection accessories for small burner controls

Plug-in base AGK11...
Cable holders AGK65..., AGK66, AGK67...
Cable strain relief elements for AGK67...

refer to Data Sheet N7201

Connection accessories for small burner controls

Plug-in base AGK13...
Plug-in housing AGK56
Accessories AGK68

refer to Data Sheet N7203

Flame detectors
- Ionization probe
- UV- flame detectors QRA2... / QRA10...
- Blue-flame detectors QRC1...

supplied by thirds
refer to Data Sheet N7712
refer to Data Sheet N7716

RC unit
ARC 4 668 9066 0
For the supervision of ionization currents in networks with nonearthed neutral conductor
PTC resistor (AC 230 V)
To burden terminal 3 (mandatory when using burners with no fan
motor connected to terminal 3)
Auxiliary unit for UV supervision
- Cable length 500 mm
- Cable length 300 mm
- Can be fitted under the plug-in base (refer to Dimensions)

AGK25

AGQ1.1A27
AGQ1.2A27

Pedestal (empty housing)

- For increasing the height of the LGB... to that of the LFM... or LFI7...

AGK21

Service adapter
- For checking the functioning of the burner controls on the burner plant
- Functional test with signal lamps
- Detector resistance measurement with a jack of 4 mm diameter

KF8872

Adapters / replacement types

No rewiring required
KF8852
LGB21... with adapter

LGB22... with adapter

LGB41... with adapter

LFI7...

KF8880

LFM1...
LFM1...-F

KF8853-K

LFI7...

KF8880

LFM1...

KF8862

LFM1...

6/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Technical data
General unit data
LGB...

Mains voltage

Mains frequency
Input current at terminal 12

Current rating
Terminal 3

Mounting position
Weight

max. 3 A (15 A for max. 0.5 s)

max. 2 A
max. 1 A
max. 5 A
(at Umax. AC 264 V or AC 253 V)
20 m at 100 pF / m
max. 3 m at 100 pF / m line capacitance
20 m
3 VA
max. 10 A (slow)
IP 40, when built in, with the exception of
the connection area (terminal base)
optional
approx. 230 g

Storage
Climatic conditions
Mechanical conditions
Temperature range
Humidity
Transport
Climatic conditions
Mechanical conditions
Temperature range
Humidity
Operation
Climatic conditions
Mechanical conditions
Temperature range
Humidity

DIN EN 60 721-3-1
class 1K3
class 1M2
-20...+60 C
< 95 % r.h.
DIN EN 60 721-3-2
class 2K3
class 2M2
-20...+60 C
< 95 % r.h.
DIN EN 60 721-3-3
class 3K3
class 3M2
-20...+60 C
< 95 % r.h.

Terminals 4, 5 and 7
Terminals 9 and 10
Terminal 12
Cable length terminals 8 and 10
Perm. cable lengths
Detector cable laid separately
Power consumption
Primary fuse
Degree of protection
-

Environmental conditions

AC 220 V 15 % ...AC 240 V +10 %

(LGB2... / LGB4...)
AC 230 V 15 % / +10 % (LGB32...!)
AC 100 V 15 % ...AC 110 V +10 %
50...60 Hz 6 %
max. 5 A
within the permissible voltage range
AC 187...264 V or AC 195...253 V

Condensation, formation of ice and ingress of water are not permitted!

7/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Flame supervision
Flame supervision with
ionization probe

Detector voltage across terminals 1 and

2 or ground (AC voltmeter Ri 10 M)
Detector current required for reliable operation
Possible detector current in operation

At mains voltage UN = AC 230 V

UN
min. 3 A
max. 100 A

The conductivity and rectifying effect of hot flame gases are used for flame supervision.
For that purpose, AC voltage is applied to the heat-resistant ionization probe which
projects into the flame. The current that flows in the presence of a flame (ionization
current) produces the flame signal which is 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, thereby ensuring that a short-circuit between ionization probe and ground
cannot simulate a flame signal (since in that case AC current would flow).
Basically, the flame supervision circuit is insensitive to adverse effects of the ignition
spark.
However, should the disturbing effects of the ignition spark on the ionization current
exceed a certain level, the electrical connections on the primary side of the ignition
transformer must be changed and / or the location of the ionization probe must be
checked.
Ionization current supervision with burner
controls operating on
AC 110 V

Since the ionization current with burner controls operating on AC 110 V is only about
50 % of those operating on AC 230 V, certain applications make it necessary to increase the ionization current with a transformer.
Capacity of transformer: Min. 2 VA
Transforming ratio: Approx. 1.1...1.5
The primary and secondary windings of the transformer must be galvanically separated.
AC 115 V

7435v01/0504

Connection of
transformer

12

LGB2...

ION
AC 115...230 V

8/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Flame supervision with

blue-flame detector
QRC1...

Perm. detector current during the prepurge max. 5 A

time (dark current)
Detector current required during
min. 50 A
operation
Possible detector current in operation
max. 80 A

M
sw
QRC1

LGB3...
+

12

7435v02/0601

Measuring circuit with the QRC1...

br
bl

Legend
M

Microammeter Ri max. 5000

sw

Black wire

br

Brown wire

bl

Blue wire

The QRC1... has been designed specifically for blue-burning flames. Incidence of light
is from the front and laterally. The flame detector is secured by means of a soft plastic
plug. 3-core connection (preamplifier integrated in the detector casing). For the different
types of flame detectors, engineering notes and technical data, refer to Data Sheet
N7716.
Flame supervision with
UV detector QRA... and
AGQ... for LGB21... /
LGB22... / LGB41...

Mains voltage
Mains frequency
Power consumption
Degree of protection
Perm. ambient temperature
In operation
During transport and storage
Perm. length of cable from QRA... to
AGQ1...A27 (use separate cable)
Mounting position
Perm. length of connecting cable from
AGQ1...A27 to LGB...
Weight of AGQ1...A27

AC 220 V 15 %...AC 240 V +10 %

50...60 Hz 6 %
4.5 VA
IP 40
-20...+60 C
-40...+70 C
max. 20 m
optional
max. 20 m
approx. 140 g
At mains voltage UN:
AC 220 V

AC 240 V

Up to the end of t10 and after controlled shutdown

DC 400 V

DC 400 V

From the beginning of t1

DC 300 V

DC 300 V

DC 380 V

DC 380 V

Detector voltage at QRA... (with no load)

Detector voltage
Load by DC measuring instrument Ri > 10 M
Up to the end of t10 and after controlled shutdown
From the beginning of t1
DC detector signals with UV detector QRA...
Measurement on the QRA...

DC 280 V

DC 280 V

Min. required

Max. possible

200 A

500 A

9/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Flame supervision with UV detector QRA... and auxiliary unit AGQ... for LGB21... / LGB22... / LGB41...
UV detector QRA...

Universal flame detector for use with gas and gas / oil burners. Incidence of light from
the front and laterally, total length 97 mm. Available with normal or, as QRA2M, with
higher sensitivity. Secured with flange and clamp. Also available as a metal encapsulated version in the form of the QRA10... (for details, refer to Data Sheet N7712).

Auxiliary unit
AGQ1...A27

A special UV auxiliary unit AGQ1...A27 is required in connection with LGB... burner

controls.
That unit is to be connected to the mains supply via 2 cables, and to the burner control
via terminals 1, 2 and 11.
Using circuitry (A) or (B), there are 2 ways to make the quench test on aging UV detectors and to detect UV light:
1. (A) Operation with a permanent line:
UV test at a higher supply voltage across the UV cell on startup and after controlled shutdown.
2. (B) Operation with a controlled line:
UV test at a higher supply voltage only on startup, that is, during the interval
between controlled startup and air pressure signal.
No voltage at the UV cell after controlled shutdown
No full substitute for mode (A) above, since an aged UV cell can regenerate
itself

LGB...
12

* 11

(B)

bl rt
sw

sw
bl AGQ1...A27

QRA

br

LGB...
12

* 11

7435a15/0704

Connection diagram
7435a19/0301

Measuring circuit

(B)
GP/SB
R/W
L
(A)
L
N

br

bl rt
sw

QRA

sw
AGQ1...A27
bl
+
-

Measurement made on the flame detector

Legend

GP

Gas pressure switch

Temperature or pressure controller

SB

Safety limit thermostat

Limit thermostat or pressure switch

With LGB41...: Terminal 3

(A)

Operation with permanent line

(B)

Operation with controlled line

10/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Functions
The function diagrams show the required or permissible input signals to the control
section and to the flame supervision circuit hatched (refer to Connection diagrams).
If these input signals are not present, the burner control will stop the startup sequence to
trigger lockout where required by safety regulations.
Preconditions for
burner startup

Burner control must be reset

The contacts of gas pressure switch GP, limit thermostat / pressure switch W,
control thermostat / pressurestat R and safety limit thermostat SB must be
closed
Fan motor M or AGK25 must be connected
Air pressure switch LP must be in its no load position

Undervoltages

LGB... burner controls are capable of detecting undervoltages. This means that load
relay AR will be deenergized if mains voltage drops below AC 160 V (for nominal AC
220...240 V) or AC 75 V (for nominal AC 100...110 V).
The burner control will automatically make a restart attempt when the supply voltage
returns to a level above AC 160 V and AC 75 V respectively.

Reversed polarity
protection

If the connections of live conductor (terminal 12) and neutral conductor (terminal 2) are
mixed up, the burner control will initiate lockout at the end of TSA.

Startup sequence

AC

Startup sequence

Start command (switching on)

This command is triggered by control thermostat / pressurestat R.
Terminal 12 receives voltage and the programming mechanism starts running.
On completion of waiting time tw with the LGB21..., or after air damper
SA has reached the nominal load position (on completion of t11) with the
LGB22... / LGB32..., fan motor M will be started.

TSA

Ignition safety time

On completion of TSA, a flame signal must be present at terminal 1.
That flame signal must be continuously available until shutdown occurs, or
else flame relay FR will be deenergized, resulting in lockout.

tw

Waiting time
During the waiting time, air pressure switch LP and flame relay FR are
tested for correct contact positions.

t1

Prepurge time
Purging the combustion chamber and the secondary heating surfaces:
Required with low-fire air volumes when using the LGB21... and with nominal
load air volumes when using the LGB22... / LGB32...
Type summary and the Function and sequence diagrams show the socalled prepurge time t1 during which air pressure switch LP must indicate that the required air pressure is available.
The effective prepurge time t1 comprises interval end tw through t3.

t3

Preignition time
During t3 and up to the end of TSA, flame relay FR is forced to close.
On completion of t3, the release of fuel is triggered at terminal 4 or at terminal 11 of the LGB41...

11/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

t3n

Postignition time
Ignition time during TSA
Just before reaching the end of TSA, ignition transformer Z will be
switched off.
This means that t3n is somewhat shorter than TSA.
This is necessary in order to give the forcedly closed flame relay FR sufficient time to drop out if there is no flame.

t4

Interval
LGB21... / LGB41...: Time to the release of the second fuel valve BV2
LGB22... / LGB32...: On completion of t4, the heat source is controlled
depending on the load (release of load controller LR)

t9

Second safety time

(Only with LGB41...)
For pilot burners with main flame supervision equipped with a pilot gas valve
ZV1.

t10

Specified time for air pressure signal

On completion of this period of time, the set air pressure must have built up, or
else lockout will occur.

t11

Programmed opening time for actuator SA

(Only with LGB22... / LGB32...)
The air damper opens until the nominal load position is reached. Only then will
fan motor M be switched on.

t12

Programmed closing time for actuator SA

(Only with LGB22... / LGB32...)
During t12, the air damper travels to the low-fire position.

B B

Interval for establishment of flame

Burner operating position reached

CD

Burner operation (generation of heat)

Nominal output or, in connection with a load controller LR, part load operation.

Shutdown by R
The burner is immediately shut down and the programming mechanism is
ready for a new start.

12/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Control sequence in
the event of fault

In principle, whenever lockout occurs, the fuel supply will immediately be shut down. If
that takes place between startup and preignition, which is not indicated by a symbol,
the usual cause is air pressure switch LP shutting down, or a premature, faulty flame
signal.
After a mains failure or in the event of undervoltage:
Premature flame signal from the start of t1:
Contacts of air pressure switch LP have
welded during tw:
No air pressure signal:
Air pressure failure on completion of t10:
Burner does not ignite:
Flame is lost during operation:

New startup with full program sequence

on power restoration
Immediate lockout
Prevention of startup
Lockout on completion of t10
Immediate lockout
Lockout on completion of TSA
Immediate lockout

Lockout

After lockout, the LGB... will remain locked (lockout cannot be changed).
This state will also be maintained in the event of mains voltage failure.

Resetting the LGB...

Whenever lockout occurs, the burner control can immediately be reset.

Lockout and control sequence indication

The position of the programming mechanism can be seen through the viewing window
on the front of the unit. In the event of fault, the programming mechanism stops and
thus the lockout indicator also. The symbol in the viewing window indicates both the
position in the control sequence and the type of fault according to the following legend:

No startup since the start control loop is open

IIII

Interval tw or t10 (LGB21...)

Interval tw or t11 (LGB22... / LGB32...)
Interval tw, t3 or TSA (LGB41...)

Air damper fully open (LGB22... / LGB32...)

Lockout due to absence of air pressure signal

Interval t1, t3 and TSA (LGB21...)

Interval t1, t3 (t12) (LGB22... / LGB32...)

Release of fuel

Lockout since there is no flame signal on completion of the first safety time

Release of second fuel valve (LGB21... / LGB41...)

Release of load controller (LGB22... / LGB32...)

Lockout since there is no flame signal on completion of the second safety time
(LGB41...)

zzzz

Partial load or nominal load operation (or return to the operating position)

13/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Connection diagrams
LGB21...

Flame supervision

Burner controls for 1- or 2-stage forced draft burners.

LGB21...: With ionization probe or auxiliary unit AGQ1...A27 for UV detector

Air damper control for prepurging with low-fire air volume.

QRA...

A
GP/SB
R/W

B B

12

12

t1

tw
t10

10

11

GP/SB

Dbr1

bv1
bv2

ION

LP

11

t3
Z
BV1

AL

HS

BV1

LP

BV2

EK2

TSA

FS

Si

BV2

L
N

7435a09/0704

t4

7435f01/1299

LGB2...

LKP
t1

Application examples

LR

NL

Control of actuators of 2-stage or 2-stage modulating burners.

RV

SA

Prepurging (t1) with low-fire air volume.

Same low-fire actuator position (switching cam III) during startup and

IV

KL

BV1

IV

IV

III

III

Zu

operation!

II

For information about actuators SA:

SQN3...: Refer to Data Sheet N7808
SQN7...: Refer to Data Sheet N7804
SQN9...: Refer to Data Sheet N7806

12

10

11

(*)

Dbr1
EK2

LP

AL

12

10

11

EK2

Z
BV1

(*)

BV1

BV2

SB

IV

a2

II

I
MS

SA

a b

L
b

a b

RV

K1

C3
V

C31
II

a b

I
MS

a b
LK

a b

R32

* Note:

R1

b
LK

SA

SQN3...121...

III

IV
N

a1

K2

A
a3

LR

BV2

HS

III
a

7435a01/0704

Si

ION

R/W

b2

b1

Si

LP

LR

SB
1

GP

R/W

AL

GP

HS

9
Dbr1

ION

7435a02/0704

SQN91.140... / 2-stage control

With 2-stage modulating burners (with gas control damper RV),

BV2 and the dotted connection between terminals (*) are not
required

14/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Connection diagrams (contd)

LGB21...

12

10

11

LP

ION

EK2
GP

AL

BV1

LR

R/W

BV2

SB

HS

6
LKP

Si

NL

b2

a1

c1

IV

III

Zu II

a2

b1

II

III

IV

TSA
t4

7435a03/0704

t1

IV

III

KL

SQN7...244 / 2-stage control

Burner without fan and without LP
2

11

QRA... with auxiliary unit AGQ1... with LGB21... (diagram 7435a06)

12

6
AGK25

7435a04/0398

Burner with fan control via auxiliary contactor (HS) with LP

12
GP/SB
R/W
L
N

3
HS AGK25

11

GP/SB
R/W
L
L
N

11

br bl rt
AGQ1 sw

sw
bl

7435a06/0704

QRA

+
-

Legend
LP

7435a16/1299

bl

Blue wire

br

Brown wire

rt

Red wire

sw Black wire

15/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Connection diagrams (contd)

LGB22... / LGB32...

Flame supervision

Burner controls for single- or 2-stage forced draft burners.

LGB22...: With ionization probe or auxiliary unit AGQ1... for UV detector

Air damper control for prepurging with nominal load air volume.

QRA...
LGB32...: With blue-flame detector QRC1...

B B

Nur LGB22...

GP/SB
R/W

LGB22... / LGB32...

12

12

3
Nocke I

10

11

ION

GP/
SB

LR
LP

LK
W

M
t11

t10

t1

t12

LP
t3
Z
BV1

11

HS

0 I

L
N

t4

Nur LGB32...
2

AL

3 1

7 10

Si

tw

1
sw

SA

br

QRC1...
BV1

12

bl
2

EK2
7435a10/0704

LR

5
TSA

LGB22.../32...

LKP
t1

FS

LR

NL

SA

7435f02/0700

BV1/2

KL
III

Zu

Application examples

III
t

II

Control of actuators of 2-stage or 2-stage modulating burners.

Prepurging (t1) with nominal load air volume.
For information about the actuators:
SQN3...: Refer to Data Sheet N7808
SQN7...: Refer to Data Sheet N7804
SQN9...: Refer to Data Sheet N7806
LGB22...

LGB22...

10

EK2

GP

11

ION

LP

AL

12

10

GP

7435a20/0704

R1
Si

b1

b2

L
A

a2

a1

III

R3

C3

III

R1
L

K2
K1

LK
II

10

2)

R3

B
N

ION
LR

HS
0

LP

SB

HS
0

BV1

Si

*
1

11

BV1

LR

BV2
N

EK2

SB

AL

S1)

R/W

7435a08/0704

12

R2

1)

C1

RV

MS

RV
II

SQN3...151... or SQN3...251...
* Note:

SA

LK

SQN90.220... / 2-stage modulating control

With 2-stage modulating burners (with gas control damper RV),

BV2 and the dotted connection between terminals marked (*) are not
required.

16/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Connection diagrams (contd)

LGB22... / LGB32...
LGB22...

LGB22...
12

10

R/W

11

LP

12

10

11

R/W

ION

LP

EK2

ION

EK2
LR

GP

AL

LR
GP

AL

BV1

BV1

BV2

BV2

SB
SB
4

a1

HS
I

b2

Si

0 I

N
NL

II

III

IV

7435a17/0704

III

KL

III

t1

TSA

II

III

IV
2

t4

SQN7...424 / 2-stage control

2-wire control
QRA... with auxiliary unit AGQ1... with LGB22... (diagram 7435a06)
12

GP/SB
R/W
L
L
N

6
AGK25

7435a04/0398

11

br bl rt
AGQ1 sw

sw
bl

7435a06/0704

QRA

+
-

Legend

Burner with fan control via auxiliary contactor (HS) with LP

LGB22... / LGB32...
12

GP/SB
R/W
L
N

LGB22... / LGB32...
11

Zu II

Burner without fan and without LP

a2

b1

IV

Single-wire control

a1

SQN7...454 / 2-stage control

I
IV

a2

b1

b2

c1
LKP

Si

HS

3
HS AGK25

11

bl

Blue wire

br

Brown wire

rt

Red wire

sw Black wire

LP

7435a16/1299

Legend
TSA

Ignition safety time

t1

Prepurge time

t4

Interval BV1 BV2

LGB22... / LGB32...: interval BV1 - LR

AL

Alarm

LR

Load controller

BV...

Fuel valve

Fan motor

EK2

Remote reset button

NL

Nominal load

ION

Ionization probe

Control thermostat or pressurestat

GP

Gas pressure switch

SB

Safety limit thermostat

HS

Mains isolator

Si

Primary fuse

KL

Low-fire

Limit thermostat

LKP

Air damper position

Ignition transformer

LP

Air pressure switch

17/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Connection diagrams (contd)

LGB41...
Burner controls for atmospheric gas burners with or without fan. No actuator control. Flame supervision with ionization probe
A

B B

tw

GP/SB
R/W

D
12

t3
7

Z
TSA
BV1

4
t4

ZV1

11
t9
5

BV2
FS

1
7435f03/0301

QRA... with auxiliary unit AGQ1... with LGB4... (Pictures

7435a21)
12

10

11

Dbr2
GP/
SB

12

Dbr1

bv1
zv1

GP/SB
R/W
L
L
N

bv2

W
AL
R

EK2

BV2

BV1

ZV1

HS

ION

br bl rt
AGQ1 sw

sw
bl

7435a21/0704

QRA
Si

+
-

L
N
7435a11/0704

ION

ION1
ZR

7435s02/0504

7435s01/0504

ION2

HR
BV1

Legend
A
B B
C

HR
BV2

BV2

ZV1

Startup (switching on by R)
Interval for establishment of flame
Operating position of burner or release of the second stage
by load controllerLR
Shutdown by R

tw

Waiting time

TSA
t3
t4
t9

Ignition safety time

Prepurge time
Interval BV1 BV2
Second safety time

Required input signals

Burner controls output signals

Connection of valves with pilot burners with main flame

supervision
Connection of valves with 2-stage atmospheric burners
with supervision of the first stage (BV1)

AL
BV...
bv...
Dbr1
Dbr2
EK2
ION
FS
GP
HR
HS
M
QRA...

R
SB
Si
W
Z
ZR
ZV1
zv1

Alarm
Fuel valve
Auxiliary switch in the fuel valves (for checking the fully
closed position)
Wire link
Wire link, required when contact bv or zv1 is missing
Remote reset button
Ionization probe
Flame signal
Gas pressure switch
Main burner
Mains isolator
(Auxiliary) fan motor
Blue-flame detector
bl
Blue
br
Brown
rt
Red
sw
Black
Control thermostat or pressurestat
Safety limit thermostat
Primary fuse
Limit thermostat
Ignition transformer
Pilot burner
Pilot gas valve
Auxiliary switch in the pilot gas valve

18/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Internal diagram and time diagram of the programming mechanisms

LGB21...
HS
a

GP/
SB

12

br

L N

Legend

0 I

b
AS
1)

ar
ba

I
a

BR

LP
6 11

b
IV

fr
a
AR

V
a

FR
b
IX
a b

VI
b a

VII
b

a b a b
II VIII

EK1

L1
2 10

AL EK2

BV1

BV2

ION

Dbr1

7435i01/0504

MS

b
I a

tw

t10

II

b
IV a

t1

t3

TSA

t4

t20

b
V a
b
VI a

b
VII a

Alarm

AR

Load relay with contact ar

AS

Unit fuse

BR

Locking relay with contact br

BV...

Fuel valve

Dbr1

Wire link

EK...

Lockout reset button

FR

Flame relay

GP

Gas pressure switch

HS

Mains isolator

ION

Ionization probe

L1

Lockout warning lamp

LP

Air pressure switch

Fan motor

MS

Synchronous motor

Control thermostat or pressurestat

SB

Safety limit thermostat

Limit thermostat or pressure switch

Ignition transformer

Start position (switching on)

Operating position of burner

Operating position of programming mechanism or start

position

7435f04/0801

b
a

AL

b
VIII a

I...IX

Cam switches

tw

Waiting time

TSA

Ignition safety time

Total running time of programming mechanism

t1

Prepurge time

t3

Preignition time

t4

Interval BV1 BV2

t10

Specified time for air pressure signal

t20

Interval up to self-shutdown of programming

mechanism

b
IX a

b
AR a

1)

Resistance between terminal 3 and N must not

2)

Only with LGB21.130A27

exceed 1.6 k

b
FR a
T = 81 s (40,5 s 2) )

19/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Internal diagram and time diagram of the programming mechanisms (contd)

LGB22... / LGB32...
HS

a br

GP/
SB

12

L N

Legend

0 I

b
AS

1)

III
b

LP
a

6 11

b
IV

fr
a b
V
VI
b
a
b a

AR

7435i02/0704

ar
a

FR

I
a

IX
a b

VII
a

BR

a b a b
II VIII
MS

EK1 L1

2 10

4
BV1

AL EK2

7
Z

BV2

Nur LGB22...

AL

Alarm

AR

Load relay with contact ar

AS

Unit fuse

BR

Locking relay with contact br

BV...

Fuel valve

EK...

Lockout reset button

FR

Flame relay

GP

Gas pressure switch

HS

Mains isolator

ION

Ionization probe

L1

Lockout warning lamp

LP

Air pressure switch

Fan motor

MS

Synchronous motor

Control thermostat or pressurestat

SB

Safety limit thermostat

Limit thermostat or pressure switch

Ignition transformer

Start position (switching on)

Nur LGB32...
1

1
sw

ION

br

QRC1...

12

bl
2
B

7435f05/1299

b
I a
b
II a

Operating position of burner

Operating position of programming mechanism or start

position

b
III a
tw

t11 + t10

t1

t12

b
IV a

I...IX

Cam switches

tw

Waiting time

TSA

Ignition safety time

Total running time of programming mechanism

t1

Prepurge time

b
V a
b
VI a

4
t3

b
VII a

TSA t4

t20

b
VIII a
b
IX a

b
AR a

t3

Preignition time

t4

Interval BV1 BV2 or BV1 LR

t10

Specified time for air pressure signal

t11

Programmed opening time for actuator SA

t12

Programmed closing time for actuator SA

t20

Interval up to self-shutdown of programming

mechanism

b
FR a
T = 81 s

1)

Resistance between terminal 3 and N must not exceed 1.6 k

20/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Internal diagram and time diagram of the programming mechanisms (contd)

LGB41...
L N

HS
a br

GP/
SB

12

0 I

AL

b
AS
I
a

ar
a

b
3

1)

III

VI
b a

VII

IX
a

L1

IV
8

AL
EK2

6
Dbr2

2 10

a
11

9 1

7
Dbr1

ZV1

BV1

BV2

ION

Ib
a

7435i03/0504

MS
EK1

Unit fuse

BR

Locking relay with contact br

BV...

Fuel valve

Dbr1

Wire link

Dbr2

Wire link terminal 6-2 required when contact bv or zv1

EK...

BR

a
b a
II VIII b

Load relay with contact ar

AS

is missing

b
a

Alarm

AR

FR

fr
a
AR

Legend

Flame relay

GP

Gas pressure switch

HR

Main burner

HS

Mains isolator

ION

Ionization probe

L1

Lockout warning lamp

Fan motor

MS

Synchronous motor

Control thermostat or pressurestat

SB

Safety limit thermostat

Limit thermostat or pressure switch

Ignition transformer

ZR

Pilot burner

ZV1

II b
a

Lockout reset button

FR

Pilot gas valve in place of BV1 in the case of pilot

burners with main flame supervision

III b
a

6
t9

IV b
a

tw

11
tw

t3 TSA

t4

t20

Vb
a
VI b
a

VII b
a

Waiting time

TSA

Ignition safety time

Total running time of programming mechanism

t3

Preignition time

t4

Interval BV1 BV2

t9

Second safety time

t20

Interval up to self-shutdown of the programming

mechanism

VIII b
a
IX b
a

5
7435f06/0301

AR b
a
FR b
a

Start position ( switching on)

Operating position of burner

Operating position of programming mechanism or start

position

T = 40,5 s
ION

HR
BV1

Cam switches

1)

Resistance between terminal 3 and N must not exceed

ION1
ZR

7435s02/0504

7435s01/0504

ION2

I...IX

1.6 k

HR
BV2

BV2

ZV1

21/22
Siemens Building Technologies
HVAC Products

CC1N7435en
07.07.2004

Dimensions
Dimensions in mm
22

7435m03/0704

53,5

5,5

LGB...

41,5

62,5

47

88
91

xxxxxxxxxx

Type

27,5

Auxiliary unit
AGQ1...A27

Dimension

reference

90,5

AGQ1.1A27

500

19

AGQ1.2A27

300

34

60
69

13

22/22
Siemens Building Technologies
HVAC Products

65,6

18

220

5,4

5,4
B 6

7435m01/0301

2004 Siemens Building Technologies Production GmbH

Subject to change!

CC1N7435en
07.07.2004