Krom Schroder PFU 780, Technical Information, Page: 68 / 70

PFU 780 · Edition 02.12 68
The default safety time during operation t
SB
in accordance with
EN 298 is 1 second. 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 (see “Project plan-
ning information”). Note the requirements of the Standards!
12 .6 Flame signal
If a flame is detected, the flame detector will supply a flame
signal.
12 .7 Fault lock-out
In the event of a fault lock-out, all valves and the ignition trans-
former are disconnected from the electrical power supply,
and a fault is signalled. Resetting must take place manually
following a fault lock-out.
12 .8 Safety interlocks (Limits)
The limiters in the safety interlock (linking of all the relevant
safety control and switching equipment for the use of the ap-
plication, e.g. safety temperature limiter, minimum/maximum
gas pressure) must isolate input ( ) from the voltage supply.
12 .9 Pilot gas valve V1
The start fuel flow rate for the pilot burner is released by pilot
gas valve V1. It opens when the safety time on start-up t
SA1
starts to elapse. It remains open until the burner is switched
off again by a normal shut-down or fault lock-out.
12 .10 Main gas valve V2
The start fuel flow rate for the main burner is released by main
gas valve V2. It opens when the safety time on start-up t
SA2
starts to elapse. It remains open until the burner is switched
off again by a normal shut-down or fault lock-out.
N (L2)
22e
16c
N
26e
30a
32c
230 V
F1
18e
2a
4a
a
2e
4e
s
2c
4c
m
sk1
V2
V1
L1 (L1)
max. 1 A, 24 V
v2
v1
6a
6e
n
c1
24 V
0 V
c2
10c
12c
10a
12a
30e
22a
P
DI
A
2
1
1
N
2
28c
26a
ϑ
1
ϑ
2
14a
14e
10e
12e
24c
20c
18a
l
20c
18a N
26a
26a
N
28c
28c
18a
Z
I
UVS
1
2
3
24c
L
N
M
V2
V1
C
µC
SK
A
S
PFU 780
12 .11 Continuous operation
The gas burner runs continuously for more than 24 hours.
12 .12 Air valve
The air valve can be used
– for cooling,
– for purging,
– to control the burner capacity in ON/OFF mode and in
High/Low mode when using a pneumatic air/gas ratio
control system.
Glossary