PFU 780 · Edition 02.12
34
4 .6 Behaviour during operation
4 .6 .1 Safety time during operation t
SB
for pilot and main burners
Parameter 14
This indicates the safety time during operation t
SB
for valves V1
and V2. The default in accordance with EN 298 is 1 s. The PFU
has also the available option of a safety time during operation
t
SB
of 2 s. Prolonging the time increases the installation avail-
ability in the case of brief-duration signal fades (e.g. fades of
the flame signal). In accordance with EN 746-2, the safety time
of the installation during operation (including closing time of
the valves) may not exceed 3 seconds (note the requirements
of the Standards).
4 .6 .2 Fault lock-out or restart, pilot burner
Parameter 12
This parameter determines whether the PFU starts a one-off
restart or performs an immediate fault lock-out for the burner
after an installation fault such as a flame failure or failure of
air flow (see also Project planning information).
Immediate fault lock-out following flame failure
Parameter 12 = 0:
Pilot burner fault lock-out.
04
t
t
SB
04
26a
16c
18e
2c–4c
88
10e
26e
30a
28c
2e–4e
V1
1
V2
ϑ
1
1
After a fault lock-out, the burner control unit can be reset,
either with the button on the front panel or using an external
button. Several burner control units can be reset in parallel
using the external button.
The PFU cannot be reset by mains failure. The fault signalling
contact does, however, open as soon as the mains voltage fails.
See also parameter 32, Behaviour of the air valve in the event
of a fault lock-out.
Parameters
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