7

ISO 9001

418

Gas Burner Controls

LGA...

The LGA... are used for the startup and supervision of atmospheric gas burners of small to medium capacity (without fan) 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 probe. Using the appropriate adapters, the LGA... can replace their predecessor types LFI7... and LFI5... in terms of function and size (refer to Ordering). LGA41.173A27 and LGA52.171B27 are suited for use with direct-fired air heaters.

CC1N7418en 05.06.2002

Siemens Building Technologies HVAC Products

Warning notes To avoid injury to persons, damage to property and the environment, the following warning notes should be observed! Do not open, interfere 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 connections terminals Check wiring and all safety functions prior to commissioning Press the lockout reset button / operating button only manually (applying a force of no more than 60 N), 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 Siting the ionization probe Ensure that the relevant national safety regulations are complied with The ionization probe and ignition electrode must be positioned such that the ignition spark cannot arc over to the ionization probe The position and 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

Installation notes Installation work must be carried out by qualified staff 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 and neutral conductors are correctly connected to terminals 1 and 2 of the burner control; otherwise, no flame signal will be generated Connect the gas pressure switch 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 burner 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 2-stage burners to terminal 5 in series with BV2

Only with LGA41...

2/11 Siemens Building Technologies HVAC Products

Only with LGA52... / LGA63...

CC1N7418en 05.06.2002

Electrical connection of ionization probe It is important to achieve practically disturbance- and loss-free signal transmission: Never run the detector cable together with other cables Line capacitance reduces the magnitude of the flame signal Use a separate cable Observe the permissible length and shielding of the detector cable (refer to Technical data) The ionization probe is not protected against electric shock hazard Locate the ionization probe such that the ignition spark cannot arc over (risk of electrical overloads) Always run the high-voltage ignition cables separate from the unit and other cables while observing the greatest possible distances The insulation resistance between ionization probe and ground must be a minimum of 50 MW, even after a large number of operating hours. Prerequisite for this is not only high quality heat-resistant insulation of the cable, but also of the ionization probe itself (ceramic holder!) A soiled ionization probe holder offers favorable conditions for surface leakage currents which reduce the magnitude of the flame signal The burner (as the counter-electrode) must be correctly earthed, or else no ionization current will flow Earthing the boiler alone does not suffice! The connection diagrams shown apply to burner controls with earthed neutral conductor. In the case of ionization current supervision in networks with nonearthed neutral conductor, terminal 2 must be connected to the earth conductor via an RC unit (part no. ARC 4 668 9066 0). In that case, it must be made certain that the relevant national safety regulations are complied with (e.g. electric shock hazard protection), since AC 230 V / 50 Hz mains voltage results in a leakage current of 2.7 mA

Commissioning notes Commissioning and maintenance work must be carried out by qualified staff When commissioning the plant or when doing maintenance work, make the following safety checks: Safety check Burner startup with no flame signal; for that purpose, open the connection between burner control and ionization probe prior to burner startup and maintain this status Burner operation with simulated loss of flame during operation; for that purpose, open the connection between burner control and ionization probe during burner operation and maintain this status No air pressure signal during t1 (only with LGA52... / LGA63... with fan) Air pressure failure during operation (only with LGA52... / LGA63...) Anticipated response Lockout at the end of TSA

a)

b)

Restart, followed by lockout at the end of TSA

c) d)

No startup Shutdown

3/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Service notes Standards CE conformity according to the directives of the European Union Electromagnetic compatibility EMC 89 / 336 EEC Directives for gas-fired appliances 90 / 396 EEC Identification code to EN 298 -AMCLXN single-stage -ATCLXN 2-stage Check wiring and all safety functions each time a unit has been replaced

Disposal notes The unit contains electrical and electronic components and may not be disposed of together with household garbage. Local and currently valid legislation must be observed. Mechanical design LGA... The gas burner controls are of plug-in design, suitable for installation in any position on burners, in control cabinets or on control panels. 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 lockout reset button (splash-proof) Plug-in base AGK11 Undervoltage detection Refer to Data Sheet 7201. In the event of undervoltage (below approximately AC 165 V), an electronic circuit ensures that the burner control will prevent burner startup. Undervoltage threshold: AC 178 V 10 V TSA: Smaller tolerance band Flame signal amplifier: Higher sensitivity, for typical applications with pilot flames

Only with LGA63.191A27

Type summary The type references given in the table refer to burner controls with no base and no accessories.
Burner control with undervoltage detection AC 220...240 V AC 100...110 V LGA41.153A27 ------2 x
1)

LGA41.173A27 ------2 x

LGA52.150B27 LGA52.171B27 LGA63.191A27 LGA52.150B17 x x 2 x --x x 2 x --X X 2 x

Connection facility for auxiliary fan ) Connection facility for air pressure switch Control outputs for gas valves Reversed polarity protection

Auxiliary fan not monitored to EN 298

4/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Ordering Gas burner control (without plug-in base) Electrical connections - Plug-in base AGK11... - Cable holders AGK65..., AGK66, AGK67... - Cable strain relief elements for AGK67... Electrical connections - Plug-in base AGK13 - Plug-in housing AGK56 - Cover AGK68 Flame detectors Ionization probe refer to Type summary refer to Data Sheet 7201

refer to Data Sheet 7203

supplied by thirds

Pedestal For increasing the height of the LGA... (62.5 mm) to that of the LFI1... or LFI5... (90 mm) Test case (for making functional tests) For testing burner controls Refer to Operating Instructions B7986

AGK21

KF8843

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 nonearthed neutral conductor) ARC 4 668 9066 0

5/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Technical data General unit data 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 Environmental conditions Transport Climatic conditions Mechanical conditions Temperature range Humidity Operation Climatic conditions Mechanical 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 (when integrated) optional approx. 180 g approx. 260 g DIN EN 60 721-3-2 class 2K2 class 2M2 -50...+60 C < 95 % r.h. DIN EN 60 721-3-3 class 3K5 class 3M2 0...+60 C for LGA41.173A27 and LGA52.171B27: -20...+60 C < 95 % r.h.

Humidity

Condensation, formation of ice and ingress of water are not permitted! Ionization probe Voltage between ionization probe and ground Required detector current Possible detector current Length of detector cable Required insulation resistance between ionization probe with its cable and ground mains voltage min. 5 A max. 100 A max. 20 m (separate cable) min. 50 MW

6/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Function Control sequence

AC 220...240 V AC 100...110 V t1 t3 t3 TSA TSAmax. t3n t4 Prepurge time Preignition time Preignition time from start of TSA Ignition safety time Max. ignition safety time Postignition time Interval BV1 BV2

(times in seconds) 1)
LGA41.153A27 ----15 --5 10 max. 2 approx. 18 LGA41.173A27 ----15 --10 20 max. 2 approx. 13 LGA52.150B27 LGA52.150B17 approx. 13 --max. 5 5 10 --approx. 18 LGA52.171B27 --approx. 13 --4.5...7.5 4.5...7.5 20 --approx. 13 LGA63.191A27 --approx. 13 --max. 10 10 20 --approx. 23

) All times specified apply to AC 220 V and AC 110 V respectively

For AC 240 V operation, above times are to 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 ) Loss of flame 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 probe The conductivity and rectifying effect of hot flame gases are used for flame supervision. For that purpose, AC voltage is applied to the ionization probe 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 probe and ground cannot simulate a flame signal (since in that case, AC current would flow).

7/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Internal diagram LGA41...

When the switch-on command is given, power is supplied to 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 preignition time, the system tilts so that e - f closes and f - g opens, BV1 receives voltage. 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...
EK L1 tz2 a b X Y Z fr c d tz1 e f g FR

TZ

1 2 SB W R L N

10

11

7 6

12 FE

AL

BV1

BV2
7418i02/0200

Legend

AL BV... EK FE FR L1 R SB TZ W Z

Fault status signal Fuel valve Lockout reset button Ionization probe Flame relay Built-in lockout warning lamp Thermostat or pressurestat Safety limit thermostat Electro-thermal timer (bimetal system) with contacts tz Limit thermostat Ignition transformer

8/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Internal diagram LGA52... / LGA63...

When the switch-on command is given, the auxiliary fan starts to run. When the air pressure switch 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 prepurge time, e - f is closed so that both 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 deenergized, 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...
EK L1 tz2 ab X Y Z fr c d tz1 e f g FR

TZ 1 2 SB W R L N AL M
1)

10

11 LP Z

12 FE

BV1

BV2
7418i01/0200

Legend

AL BV... EK FE FR L1 LP M R SB TZ W Z
1)

Fault status signal Fuel valve Lockout reset button Ionization probe Flame relay Built-in lockout warning lamp Air pressure switch Auxiliary fan Thermostat or pressurestat Safety limit thermostat Electro-thermal timer (bimetal system) with contacts tz Limit thermostat Ignition transformer
Not monitored to EN 298

9/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Connection diagram LGA41...

FR 1 SB W R Z
BV1

Control sequence
LGA41...
A
SB R/W Z t3

B
t3n TSA t4

D
1 7 4 5 12

11

10

12

FE
BV2

BV1 BV2

AL

L N

FS
7418a04/0200
7418f01/0200

LGA52... / LGA63...
LGA52... / 63...
FR 1 SB W R M
1)

A
SB R/W LP

D
1 11 8 9 6 7 4 5 12

9 LP

11

10

12

FE Z
BV1

M 9

BV2

AL

L N

7418a05/0200

6 Z BV1 BV2 FS

t1

t3 TSA

t4

7418f02/0200

Legend

AL BV... FE FR FS LP

Fault status signal Fuel valve Ionization probe Flame relay Flame signal Air pressure switch

M R SB W Z

Auxiliary fan Thermostat or pressurestat Safety limit thermostat Limit thermostat Ignition transformer

Required input signals Burner controls output signals

1)

Not monitored to EN 298

A B

Commencement of startup sequence Time of flame establishment

C D

Operating position Controlled shutdown by R

t1 t3 t3

Prepurge Preignition time Preignition time from the start of TSA

t3n t4 TSA

Postignition Interval BV1 BV2 Ignition safety time

10/11 Siemens Building Technologies HVAC Products CC1N7418en 05.06.2002

Dimensions Dimensions in mm LGA...

5,5 62,5

25 88 91

25

41,5

LGA... with plug-in base AGK11... and cable gland holder AGK65...

xxxxxxxxxx

2002 Landis & Staefa Produktion GmbH Subject to change Siemens Building Technologies HVAC Products

22

62,5

47

7418m01/0102

11/11 CC1N7418en 05.06.2002