ABB REG650 ANSI, Technical Manual

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8.5.7 Operation principle
Breaker failure protection, 3-phase activation and output CCRBRF is initiated from
protection trip command, either from protection functions within the IED or from
external protection devices.
The start 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 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:
• 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.
S
R SR
Q
OR
AND
AND
30 ms
t
150 ms
START
STL1
OR
BackupTrip L1
BFP Started L1
Reset L1
BLOCK
Retrip Time Out L1
IEC09000976-2-en.vsd
Time out L1
IEC09000976 V2 EN
Figure 109: Simplified logic scheme of the CCRBRF starting logic
Section 8
1MRK 502 048-UEN A
Current protection
224
Technical manual