Nu-Way MDFL 3300, Installation And Maintenance Manual

Page: 22 / 49

MDFL 3300 & MDFL 4000 Issue 2 08/08 Page 21
BURNER CONTROLLER : SIEMENS LFL 1
In the event of a fault condition the sequence
disc stops rotating, with the symbol appearing
above the indicator mark indicating the nature
of the fault.
If the fault leads to a lockout condition the
orange lockout indicator will be illuminated.
Symbol Lockout Fault
No
Before allowing the sequence to begin the unit carries out the following checks:
• Burner Controller not in lockout position.
• Air Damper closed (proved by limit switch supplying voltage from terminal 11
to terminal 8).
• Fuel Valves closed (proved by limit switch supplying voltage to terminal 12)
• Air Pressure Switch indicating ‘no air’ (proved by voltage present on terminal
4).
• Fuel Gas Pressure Switch, Limit Thermostat or Limit Pressure Switch all
closed (proved by continuity between terminals 4 and 5).
▲
No
Interruption to sequence whilst controller waits for the air damper to drive to
open position (proved by servo motor limit switch).
P
Yes
Lockout caused by the failure of the air pressure switch to changeover from the
‘no air’ position shortly after the start of the pre-purge.
■
Yes Lockout caused by a fault in the flame supervision circuit.
▼
No
Interruption to sequence whilst controller waits for the air damper to drive to
start position (proved by servo motor limit switch).
None
Yes
Lockout during the pre-ignition period not marked by a symbol is usually
caused by premature flame signal.
1
Yes
Lockout caused by the absence of a flame signal at the end of the first safety
period (time for start flame establishment).
2
Yes
Lockout caused by the absence of a flame signal at the end of the second
safety period (time for main flame establishment).
I
Yes Lockout caused by the loss of the flame signal during normal operation.
Yes
Lockout caused by flame signal (either real or due to extraneous light) or flame
supervision circuit fault after completion of shutdown.
Enlarged Detail of Sequence Indicator
Failure of one or more of the pre-start checks interrupts the start-up procedure.