VAMP 140
2.2.7.
20
Overcurrent and earth-fault relay
Technical description
Flt
Circuit-breaker failure protection CBFP (50BF)
The operation of the circuit-breaker failure protection is based
on the supervision of the operating time, from the pick-up of
the configured trip relay to the dropout of the same relay. If
that time is longer than the operating time of the CBFP stage,
the CBFP stage activates another output relay, which will
remain activated, until the primary trip relay resets.
The CBFP stage functions also in earth-fault situations,
because its function is merely based on supervision of the
function of the output relay T1.
Figure 2.2.7-1 Block diagram of the circuit-breaker failure protection
The CBFP blocking signal prevents the CBFP stage from
operating, when the output relays or any other protection
function is operated by forced control.
Parameters of the circuit-breaker failure protection
CBFP (50BF)
Parameter:
Setting
CBRel
values
t>
SCntr
Recorded
values
TCntr
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%
Maximum value of fault current as
per times Ion
Value/unit:
Relay to be supervised
s
Operation time
Start counter (Start) reading
Trip counter (Trip) reading
VAMP Ltd
VM140.EN011