Technical information

IFD 244 · Edition 03.08
12
Connect voltage
Safety interlocks (Limits)
In the event of fault signal: reset
Flame fails:
safety time during operation t
SB
starts to elapse,
restart or fault lock-out
Start-up position/standby
Normal shut-down
via *signal
Flame detected:
operation
Flame simulation check
Safety time on start-up t
SA
running,
gas valve opens, ignition in process
Gas valve closes
No flame detected:
fault lock-out
Waiting time t
W
running,
start-up with * signal
01
04
00
00
02
04
Program sequence3.2
Normal start-up
If, after applying voltage, an “old” fault is still being signalled,
it will be necessary to reset this first. The safety interlocks are
closed, the IFD reverts to start-up position/standby and con-
ducts a self-test. If it does not determine a malfunction of the
internal electronic circuitry or of the flame sensor, the flame
simulation check then commences. This takes place in start-
up position during the waiting time tW. If no flame simulation
is detected during that period, the safety time on start-up tSA
then starts to elapse. Voltage is supplied to the gas valve and
ignition transformer. The burner starts. Once the safety time on
start-up tSA has elapsed, the start-up process is completed.
Start-up without flame signal
If, after the gas valve has opened and the ignition has been
activated, no flame is detected during the safety time on start-
up tSA, a fault lock-out will then occur.
Behaviour in the event of flame failure during operation
If the flame fails during operation, the IFD 244 will perform a
fault lock-out within the safety time during operation tSB. The
valve is closed immediately. The burner will be restarted once.
If the burner does not function, a fault lock-out occurs.
Function