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BCU 370 · Edition 01.19
49
Parameters
4 .4 .4 Restart after flame failure during operation
Parameter 08
Determines whether a restart will be attempted follow-
ing a safety shut-down during operation.
For burners with occasionally unstable flame signals
during operation, a one-off restart can be attempted.
Parameter 08 = 0: Off. A fault lock-out will occur in the
event of a flame failure during operation
In the event of an installation fault (e.g. flame failure or
air pressure failure), the burner control unit performs a
fault lock-out within the safety time during operation
t
SB
. This involves disconnecting the power from the gas
valves. The fault signalling contact closes, the display
blinks and shows the current program status, see page
79 (Status and fault messages for PROFIBUS DP).
Parameter 08 = 1: On. A restart will take place after a
flame failure during operation.
If the BCU detects an installation fault (e.g. flame fail-
ure) after the second flame proving period has elapsed,
the valves are closed and the operation signalling con-
tact is opened within time t
SB
. The burner control unit
now attempts to restart the burner once. The restart
begins with pre-purge. For further restart attempts, the
burner must have been operational for at least 2 sec-
onds.
If the burner does not function, a fault lock-out occurs.
The display blinks and shows the cause of the fault.
In accordance with EN 746-2 and EN 676, a restart
may be attempted under certain conditions. The safety
of the system must not be impaired. Please note appli-
cation standards.
4 .4 .5 Last fault signal
Parameter 03
The BCU shows the last fault message.
In order to analyze a burner system, the last fault mes-
sage can be called up. In addition, parameters 81 to 90
show the last 10 messages. Extended diagnostics is
possible using the BCSoft software.