ABB Relion 650 Series Technical Manual page 214

Section 6
Current protection
6.11.7 Operation principle
The breaker failure protection (CSPRBRF 50BF) is initiated from protection trip command, either
from protection functions within the IED or from external protection devices.
The initiate signal can be phase selective or general (for all three phases). Phase selective initiate
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 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 retrip is only
performed if breaker is indicated as closed.
The initiate 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, 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.
BLOCK
PU_A
PICKUP
52a
ANSI11000034 V1 EN-US
Figure 108: 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
208
Current
AND
Current &
Contact
AND
OR
AND
Contact
Pickup_PH .
© Copyright 2011 ABB Power Grids. All rights reserved
1 out of 4 where it is sufficient to
t1
t
AND
OR
AND
B C
ANSI11000034-1-en.vsd
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1 out of 3 where it is
2 out of 4 where
TRRET
OR
Line distance protection REL650
Technical manual