BCU 580 · Edition 11.15
120
19 Glossary
19 .1 Waiting time t
W
In standby, the waiting time t
W
starts to elapse in the back-
ground. During the waiting time (display
H0
), a self-test is
conducted to detect errors in internal and external circuit
components. If no malfunction is detected, the BCU can start
the burner.
19 .2 Ignition time t
Z
If no malfunction is detected during the waiting time t
W
, the
ignition time t
Z
then starts to elapse. Voltage is supplied to gas
valves V1 and V2 as well as to the ignition transformer. The
burner is ignited. The duration of the ignition time is either 1,
2, 3 or 6 s (depending on safety time t
SA1
selected).
19 .3 Safety interlocks
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.
19 .4 Safety time on start-up t
SA1
This refers to the period of time between switching on and
switching off of the gas valve, when no flame signal is detected.
The safety time on start-up t
SA1
(2, 3, 5 or 10 s) is the minimum
operating time of the burner and burner control unit.
19 .5 Safety time during operation t
SB
08
t
t
SB
88
5
13
V1
1
14
V2
2
ϑ
1
ϑ
2
8
4
1
46
11
9
41
42
L1
1
43
2
17-18
08
If the flame fails during operation, the output for valve V2 is
disconnected within the safety time t
SB
.
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. Note the require-
ments of the standards!