Hitachi Relion 670 Series Applications Manual page 175

1MRK506375-UEN Rev. N
8.7.1 Function revision history
8.7.2 Identification
8.7.3 Application
In the design of the fault clearance system the N-1 criterion is often used. This means that a fault
needs to be cleared even if any component in the fault clearance system is faulty. One necessary
component in the fault clearance system is the circuit breaker.
It is from practical and economical reason not feasible to duplicate the circuit breaker for the
protected object. Instead a breaker failure protection is used.
Breaker failure protection (CCRWRBRF) will issue a backup trip command to the adjacent circuit
breakers in case of failure to trip of the "normal" circuit breaker for the protected object. The detection
of failure to break the current through the breaker is made by means of either current measurement
or status of CB auxiliary contact.
CCRWRBRF can also give a retrip. This means that a separate trip signal is sent to the protected
circuit breaker first. The retrip function can be used to increase the probability of operation of the
breaker, or it can be used to avoid backup trip of many breakers in case of mistakes during relay
maintenance and testing.
8.7.4 Setting guidelines
The parameters for Breaker failure protection CCRWRBRF application function are set via the local
HMI or Protection and Control Manager PCM600.
Common base IED values for primary current (IBase), primary voltage (UBase) and primary power
(SBase) are set in the global base values for settings function GBASVAL.
GlobalBaseSel: To select GBASVAL function for reference of base values.
Operation: For breaker failure protection Off/On.
FunctionMode: It defines the way the detection of failure of the breaker is performed. In the mode
Current, the current measurement is used for the detection. In the mode CB Pos, the CB auxiliary
contact status is used as indicator of failure of the breaker. The mode Current or CB Pos means that
both ways of detections can be activated. CB Pos mode can be usable in applications where the fault
current through the circuit breaker is small. This can be the case for some generator protection
application (for example reverse power protection) or in case of line ends with weak end infeed.
RetripMode: This setting states how the retrip function shall operate. Retrip Off means that the retrip
function is not activated. CB Pos Check (circuit breaker position check) and Current means that a
phase current must be larger than the operate level to allow retrip. CB Pos Check (circuit breaker
position check) and Contact means retrip is done when circuit breaker is closed (breaker position is
used). No CBPos Check means retrip is done without any check of breaker position.
Railway application RER670
Application manual
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Section 8
Current protection
GUID-3A043295-3AE3-437E-BBE9-D7FD6F349892 v3
M13916-3 v8
M11546-4 v12
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