BCU 440 · Edition 01.17 21
Project planning information
6.4 Safety interlocks (Limits)
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 and maximum gas pressure, tightness con-
trol) must isolate terminal 1 from the voltage supply. If
fuse F1 has tripped, this is indicated by a blinking
50
on the display.
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.
6.5 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 and 12 are
not overloaded (> 3 A), using an ohmmeter, for example.
All safety-relevant outputs of the BCU are fused with an
internal, non-replaceable fuse see, 9 (Connection
diagram). This affects the outputs for ignition and gas
valve V1. In the event that the internal fuse for these
outputs blows, the unit must be sent to the manufac-
turer for repair.
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