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DMC3S - Manual - 08 - 2021
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Breaker coils control monitoring
Preface
The breaker open/close circuit can be controlled by the relay to report any faults capable of caus-
ing failure of operation of the breaker due to trip of protections or due to the operator's intentional
commands.
The 74TCS monitoring function detects faults such as circuit interruptions, loss of auxiliary voltage
or interruption/short circuit of the open/close coils.
The supervision is implemented by means of detection of the current circulating in the breaker's
coilss, the operating logic is selected automatically by the protection function itself.
Operating logic
The command circuit monitoring function can be enabled or disabled; to do so set to
ON
or
OFF
the
parameter
FMCBCOIL Enable
in the menu
Set \ Breaker coils control monitoring
.
When the breaker is closed, diagnostics are run on the opening coils, and vice-versa.
If the position is not congruent, diagnostics are run on both coilss.
A circuit fault is reported when the current I
R
is below the set threshold during the CH pulse (close
command) or AP pulse (open command). The duration of the CH and AP pulses can be set in the
menu
Set \ Breaker coils control monitoring \ CH pulse duration
and
Set \ Breaker coils control monitoring \ AP pulse duration.
Since this condition can arise even when the breaker's opening circuit is operating (e.g.: the protec-
tion has commanded opening but the opening time has not yet passed), to prevent incorrect report-
ing, the fault condition is controlled cyclically every 60 s, the first under threshold condition initiates
the START, and if this condition persists for a further 120 s (60+60) the TRIP is actuated; if, on the
other hand, I
R
returns above the thrshold everything is working properly and the START is aborted.
+V
AUX
-V
AUX
-V
AUX
Command
Open
Command
Closed
R
THRESHOLD
5 ms
Alarm
Normal
I
R
I
R
EXAMPLE OF NORMAL
COILS OPERATION
THRESHOLD
2 ÷ 5 ms
I
R
START
TRIP
60 s
60 s
Alarm
Normal
3 PULSES UNDER THRESHOLD PRODUCE A TRIP
