Siemens LFL1.335 - Fault Conditions and Lockout Indication

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Building Technologies Division CC1N7451en
20.11.2017
Control sequence under fault conditions and lockout indication
In case of any faults, the fuel supply is always interrupted immediately. In the event of
any kind of fault, the sequence switch will stop and, with it, the lockout indicator.
The symbol above the indicator’s reading mark gives the type of fault:

No start
 One of the contacts is not closed (also refer to «Preconditions for burner startup»)
 Extraneous light
Lockout during or after completion of the control sequence.
Examples:
– Flames that have not extinguished
– Leaking fuel valves
– Defect in the flame supervision circuit
=
Startup
interruption
 Terminal 8 has not received the OPEN signal from end switch «a»
 Terminals 6, 7 and 14 remain live until the fault has been corrected
P
Lockout
 No indication of air pressure at the beginning of the air pressure check
 Loss of air pressure after the air pressure check

Lockout
 Defect in the flame supervision circuit
>
Startup
interruption
 Terminal 8 has not received the positioning signal from auxiliary switch «m» for the
low-fire position
 Terminals 6, 7 and 14 remain live until the fault has been corrected
1
Lockout
 No flame signal on completion of safety time «TSA»
2
Lockout
 No flame signal on completion of the second safety time (flame signal of main flame
with interrupted pilot burners)
I
Lockout
 Loss of flame signal during operation
After the reset, the burner control sequence switch first returns to the start position and
then initiates a burner restart. If lockout occurs any other moment in time between start
and preignition not indicated by a symbol, the usual cause is a premature flame signal,
that is, a faulty flame signal, caused for instance by a self-igniting UV tube.
a-b Startup sequence
b-b´ Idle steps
(with no contact confirmation)
b (b´)-a Postpurge program

Duration of safety time with
direct spark flame burners

Duration of safety times with
interrupted pilot burners
LFL1... Series 01 LFL1... Series 02
 When lockout has occurred, the burner control can immediately be reset.
– Do not press the lockout reset button for more than 10 seconds
 The sequence switch always returns to its start position first
– After resetting
– After correction of a fault which resulted in plant shutdown
– After each power failure
During that period of time, power is only fed to terminals 7 and 9...11.
 The burner control then carries out a burner restart

Note!
Do not press the lockout reset button for more than 10 seconds.
Lockout indicator