PFU 780 · Edition 02.12l
35
Parameters
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 availability 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.
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