CC1N7761E 3
In principle the program sequence is the same as with burner start-up without ignition
spark supervision. Exceptions:
- If the flame safeguard does not receive any input signal during the short pre-ignition
time (UL2 on position «Short pre-ignition»), lockout occurs before any gas is released,
i.e. safety time t
2 = 0 s.
- With ignition spark supervision the safety time for the pilot burner can only be adjusted
between 0 ... 6 s (in the time diagram of the switching mechanism: t
2z).
Controlled shutdown is carried out as soon as one control or supervision device in the
control loop between terminal 8 and 9 open its contact, i.e. the fuel valves are closed
immediately. The switching mechanism starts again and now programs the post-purge, if
necessary. On completion of the post-purge time the switching mechanism has again
reached its start position in which it remains until the next switching on command is
received.
The flame supervision restarts again during the post-purge time; therefore every flame
signal during this time leads to a lockout.
After actuation of the built-in or external reset button the switching mechanism runs
through to its start position. The only burner plant component which is operated during
this time is a fan motor connected to terminal 17. As the limit thermostat or pressurestat
normally continues to call for heat, the unit immediately initiates a restart as soon as it has
reached its start position.
The program indicator continuously shows the respective phase of the burner start-up
sequence. The letters correspond to those of the switching mechanism diagram next to
the viewing window. The figures indicate the remaining pre-purge time. If lockout occurs
the switching mechanism and the program indicator stop and by this means determine
the operating phase during which the lockout occurred.
Í Remaining pre-purge time approx. 35 s
Valve 2 at terminal 7 is opened Î
Burner start-up with
ignition spark
supervision
Control program
following a controlled
shutdown
Control program
following lockout reset
Program Indicator
Reading the program
indicator
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