Operation Principle - ABB REG650 Technical Manual

1MRK 502 043-UUS B
8.5.7
Technical Manual

Operation principle

Breaker failure protection, 3-phase activation and output CCRBRF (50BF) is initiated
from protection trip command, either from protection functions within the IED or from
external protection devices.
The initiate signal is general for all three phases. A re-trip attempt can be made after a
set time delay. The re-trip function can be done with or without CB position check
based on current and/or contact evaluation. With the current check the re-trip is only
performed if the current through the circuit breaker is larger than the operate current
level. With contact check the re-trip is only performed if breaker is indicated as closed.
The initiate signal can be an internal or external protection trip signal. This signal will
initiate 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:
• 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.
• Back-up trip is always made with current or contact check. It is possible to have
this option activated for small load currents only.
Section 8
Current protection
217