Honeywell Krom Schroder BCU 580 - 19 Glossary; 19.1 Waiting time tW; 19.2 Ignition time tZ; 19.3 Safety interlocks

BCU 580 · Edition 11.15l 127
Glossary
19 Glossary
19.1 Waiting time t
W
In standby, the waiting time t
W
starts to elapse in the
background. During the waiting time (display H0), a self-
test is conducted to detect errors in internal and exter-
nal 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 sup-
plied 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 rel-
evant safety control and switching equipment for the
use of the application, 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
ϑ1
ϑ2
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 accord-
ance 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 requirements of the stand-
ards!