Woodward highprotec MRI4, User Manual

Page: 559 / 727

Supervision
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
overvoltage 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.
Trigger Modes
There are three trigger modes for the
CBF module available. In addition to that, there are three assignable trigger
inputs available that might trigger the
CBF module even if they are not assigned within the breaker manager onto
the breaker that is to be monitored.
• All Trips: All trip signals that are assigned to this breaker (within the trip manager) will start the CBF module (please
refer also to section „Trigger signals of the Circuit Breaker Failure“).
•
Current Trips: All current trips that are assigned to this breaker (within the trip manager) will start the CBF module
(please refer also to section „Trigger signals of the Circuit Breaker Failure“).
• External Trips: All external trips that are assigned to this breaker (within the trip manager) will start the CBF module
(please refer also to section „Trigger signals of the Circuit Breaker Failure“).
559 MRI4 DOK-HB-MRI4-2E