Honeywell Krom Schroeder BCU 480, Руководство пользователя, Страница: 59 / 83

BCU 480 · Edition 03.16l 59
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6 .4 Minimum burner on time
Even if the start-up signal (
ϑ
) is applied only briefly, the
time set under parameter 20 elapses. The minimum
burner on time t
B
can be extended beyond the safety
time t
SA
to max. 25 s.
The signal inputs for the pilot/main burner start-up sig-
nal cannot be used for a safety shut-down because the
unit controls the valves until the minimum burner on
time has elapsed.
04 06 07 08
t
t
SA2
t
B
9
12 V1
1
14 V2
2
2
1
24
21
88
4
5
2
18-19
16-17
28-29
ϑ
1
ϑ
2
In the case of pilot/main burner monitoring, the mini-
mum burner on time only has an effect on the behav-
iour of the main burner. The minimum burner on time
for the pilot burner is limited to the safety time on start-
up (t
SA
).
Background: the pilot burner is only used in single-
stage operation.
6 .5 Safety interlocks (Limits)
The limiters in the safety interlock (linking of all the rele-
vant safety control and switching equipment for the use
of the application, e.g. safety temperature limiter, mini-
mum and maximum gas pressure, tightness control)
must isolate terminal 5 from the voltage supply. If the
safety interlock is interrupted or if fuse F1 has tripped,
the display shows a blinking
51
to indicate a fault.
If the safety interlocks fail, an immediate program abort
with switch-off of all outputs occurs (even during the
safety time). If the safety interlocks are operational
again or the unit is switched back on, the program run is
restarted in standby.
6 .6 Protection of safety-relevant outputs
When commissioning, do not switch the safety-relevant
outputs to a short-circuit.
Before switching on, ensure that outputs 7, 12 and 14
are not overloaded (> 3 A), using an ohmmeter, for ex-
ample.
All safety-relevant outputs of the BCU are fused with
an internal, non-replaceable fuse, see page 13
(Connection diagrams). This affects the outputs for ig-
nition, gas valve V1 and gas valve V2. In the event that
the internal fuse for these outputs blows, the unit must
be sent to the manufacturer for repair.