Technical information

IFD 258 · Edition 03.08
13
Connect voltage
Safety interlocks (Li)
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 signalling contact closes
Flame simulation check
Safety time on start-up t
SA
running,
gas valve opens, ignition in process
Operation signalling contact opens,
gas valve closes
No flame detected:
fault lock-out
Waiting time t
W
running,
start-up with * signal
01
04
00
00
02
04
Function
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
conducts 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 t
W
.
If no flame simulation is detected during that period, the safety
time on start-up t
SA
then starts to elapse. Voltage is supplied
to the gas valve and ignition transformer. The burner starts.
After the safety time on start-up t
SA
has elapsed, the operation
signalling contact closes. This completes start-up.
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 t
SA
, a fault lock-out will then occur.
Behaviour in the event of flame failure during operation
If the flame fails during operation, the IFD 258 will perform
a fault lock-out within the safety time during operation t
SB
.
Depending on the setting of the program selector switch, the
valves will be closed immediately or the burner will be restarted
once. If the burner does not function, a fault lock-out occurs.