Principle Of Operation - ABB Relion 670 Series Technical Reference Manual

1MRK 505 208-UEN B
6.4.2
Technical reference manual
CCRBRF function can be programmed to give a single- or three-phase re-trip of
the own breaker to avoid unnecessary tripping of surrounding breakers at an
incorrect initiation due to mistakes during testing.

Principle of operation

Breaker failure protection CCRBRF is initiated from protection trip command,
either from protection functions within the IED or from external protection devices.
The start signal can be phase selective or general (for all three phases). Phase
selective start signals enable single pole re-trip function. This means that a second
attempt to open the breaker is done. The re-trip attempt can be made after a set
time delay. For transmission lines single pole trip and autoreclosing is often used.
The re-trip function can be phase selective if it is initiated from phase selective line
protection. The re-trip function can be done with or without current check. With
the current check the re-trip is only performed if the current through the circuit
breaker is larger than the operate current level.
The start signal can be an internal or external protection trip signal. This signal will
start the back-up trip timer. If the opening of the breaker is successful this is
detected by the function, by detection of either low current through RMS
evaluation and a special adapted current algorithm or by open contact indication.
The special algorithm enables a very fast detection of successful breaker opening,
that is, fast resetting of the current measurement. If the current and/or contact
detection has not detected breaker opening before the back-up timer has run its
time a back-up trip is initiated.
Further the following possibilities are available:
• The minimum length of the re-trip pulse, the back-up trip pulse and the back-
up trip pulse 2 are settable. The re-trip pulse, the back-up trip pulse and the back-
up trip pulse 2 will however sustain as long as there is an indication of closed
breaker.
• In the current detection it is possible to use three different options: 1 out of 3
where it is sufficient to detect failure to open (high current) in one pole, 1 out
of 4 where it is sufficient to detect failure to open (high current) in one pole or
high residual current and 2 out of 4 where at least two current (phase current and/
or residual current) shall be high for breaker failure detection.
• The current detection level for the residual current can be set different from the
setting of phase current detection.
• It is possible to have different back-up time delays for single-phase faults and
for multi-phase faults.
• The back-up trip can be made without current check. It is possible to have this
option activated for small load currents only.
• It is possible to have instantaneous back-up trip function if a signal is high if
the circuit breaker is insufficient to clear faults, for example at low gas pressure.
Section 6
Current protection
177