Siemens LOA24.171B27 - Operation and Fault Handling; Startup Preconditions; Fault Control Sequence; Lockout and Reset Procedures

44 ซ.บรมราชชนนี 70 ถ.บรมราชชนนี ศาลาธรรมสพน์ ทวีวัฒนา กทม. 10170.
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Function
Preconditions
for startup
Undervoltage detection
Control sequence in
the event of fault
The relevant function diagram shows 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.
 Burner control is reset

 The contacts of the limit thermostat / pressure switch, the control thermostat /
pressurestat and the safety limit thermostat must be closed, heat request present
on terminal 1
 No undervoltage

 Flame detector is darkened, no extraneous light
An additional electronic circuit ensures that if mains voltage drops below approximately
AC 165 V (at UN = AC 220...240 V), burner startup will be prevented, or – without
release of oil – lockout will be triggered.
Whenever lockout occurs, the outputs for the fuel valves, the burner motor, oil
preheater and ignition equipment will immediately be deactivated (<1 second).
The lockout indication lamp lights up red and terminal 10 («AL») for remote lockout
indication receives voltage.
This state is also maintained in the event of mains voltage failure.
Cause
Response
Mains voltage failure
Restart
Extraneous light on burner startup
Lockout;
with LOA25... / LOA28...:
Prevention of start
No flame at the end of «TSA»
Lockout
Loss of flame during operation
Repetition
Lockout
After lockout, the LOA will remain locked (lockout cannot be changed).
This state will also be maintained in the event of power failures.
Reset of burner control
After lockout, the burner control can be reset after 60...90 seconds (also refer to
«Warning notes»).
Indications
Lockout position
The lockout position is indicated with the lamp integrated in the lockout reset button.
Flame strength
Only with LOA36...
Indication of the flame strength (green LED) is used for checking the flame signal.
To ensure reliable burner operation, this LED must be lit.
If the green LED flickers or extinguishes during burner operation, the light conditions at
the burner are poor, caused by dirt for instance.
Operation
Only with LOA36...
When the contacts of the control thermostat are closed, the orange LED is lit, indicating
the start of the oil preheater’s heating up phase (if present).
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Building Technologies Division
CC1N7118en
19.05.2016