Supervision
Locking
A locking signal will be issued simultaneously with the
CBF-Signal (Trip). The locking signal is permanent. This
signal has to be acknowledged at the HMI.
Note on devices that offer Wide Frequency Range measurement:
The supervision scheme 50BF will be blocked as soon as the frequency
differs more than 5% from the nominal frequency. As long as the frequency
differs more than 5% from the nominal frequency the supervision scheme
“50BF and CB Pos” will work according to the “CB Pos” scheme.
Supervision Schemes
Up to three supvervision schemes are available depending on the ordered device type and variant in order to detect
a circuit breaker failure.
50BF*
A supervision timer will be started as soon as the
CBFmodule is triggered by a trip signal. A breaker failure will be
detected and a signal will be issued if the measured current does not fall below a set threshold while this timer runs
down.
This supervision scheme is available within protective relays that offer current measurement.
CB Pos
A supervision timer will be started as soon as the
CBF module is triggered by a trip signal. A breaker failure will be
detected and a signal will be issued if the evaluation of the position indicators of the circuit breaker does not indicate
that the breaker has been switched off sucessfully while this timer runs down.
This supervision scheme is available within all protective relays. This scheme is recommended if breaker failures
have to be detected while there is no or not much load flow (small currents). This might e.g. be the case if overvolta-
ge or overfrequency is supervisioned for a Gen-Set that is running in Stand-by.
50 BF and CB Pos*
A supervision timer will be started as soon as the
CBF module is triggered by a trip signal. A breaker failure will be
detected and a signal will be issued if the measured current does not fall below a set threshold and if simultaneously
the evaluation of the position indicators of the circuit breaker does not indicate that the breaker has been switched
off sucessfully while this timer runs down.
This scheme is recommended if breaker failures have to be double checked. This scheme will issue a trip command
to the upstream breaker even if position indicators indicate misleadingly (faulty) that the breaker has been opened
or if the current measurement indicates misleadingly (faulty) that the breaker is now in the open position.
*=only available in protective relays that offer current measurement.
506
MRU4
DOK-HB-MRU4-2E
