Application; Setting Guidelines - ABB RET650 Applications Manual

1MRK 504 169-UEN A
7.6.2
7.6.3
Transformer protection RET650 2.2 IEC
Application manual

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, 3-phase activation and output (CCRBRF) will issue a
back-up trip command to 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 current measurement or as
detection of remaining trip signal (unconditional).
CCRBRF can also give a re-trip. This means that a second trip signal is sent to the
protected circuit breaker. The re-trip function can be used to increase the
probability of operation of the breaker, or it can be used to avoid back-up trip of
many breakers in case of mistakes during relay maintenance and testing.

Setting guidelines

The parameters for Breaker failure protection 3-phase activation and output
CCRBRF are set via the local HMI or PCM600.
The following settings can be done for the breaker failure protection.
GlobalBaseSel: Selects the global base value group used by the function to define
IBase, UBase and SBase as applicable.
Operation: Off/On
FunctionMode This parameter can be set Current or Contact. This states 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 Contact the long duration of
breaker position signal is used as indicator of failure of the breaker. The mode
Current/Contact means that both ways of detections are activated. Contact 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 re-trip function shall operate. Retrip Off
means that the re-trip 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 re-trip. CB Pos Check (circuit breaker position check) and
Contact means re-trip is done when circuit breaker is closed (breaker position is
used). No CBPos Check means re-trip is done without any check of breaker
position.
Section 7
Current protection
M13916-3 v7
M11546-4 v9
137