ABB Relion 650 Series Technical Manual page 210

Section 6
Current protection
6.10.7 Operation principle
Breaker failure protection (CCRBRF) 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 current or contact 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. 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, both
by detection of low RMS current and by a special adapted algorithm. The special algorithm enables
a very fast detection of successful breaker opening, that is, fast resetting of the current
measurement. If the current 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:
sufficient to detect failure to open (high current) in one pole,
detect failure to open (high current) in one pole or high residual current and
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.
IEC08000007 V1 EN-US
Figure 106: Simplified logic scheme of the retrip function
Internal logical signals PU_A, PU_B, PU_C have logical value 1 when current in respective phase has
magnitude larger than setting parameter
Internal logical signal PU_N has logical value 1 when neutral current has magnitude larger than
setting parameter
204
Current
BLOCK
STIL1
START
CBCLD
Pickup_N .
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AND
Current &
Contact
AND AND
OR
AND AND
Contact
Pickup_PH .
1MRK 506 326-UUS B
1 out of 3 where it is
1 out of 4 where it is sufficient to
2 out of 4 where
t1
t
OR
OR
L2 L3
en08000007.vsd
Line distance protection REL650
Technical manual
M16914-3 v2
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