Calculating Settings For Breaker Failure Protection Lv-Side Ccrbrf - ABB Relion 650 Series Applications Manual

1MRK 504 124-UEN B
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4. Set
IP> should be set lower than the smallest current to be detected by the differential
protection which is set 25 % of
5. Set
IN> should be set lower than the smallest current to be detected by the most sensitive
step of the residual ovecurrent protection which is 100 A.
6. Set the re-tip time delay
7. Set
The delay time of the breaker failure protection (BuTrip) is chosen according to figure 21.
The maximum opening time of the circuit breaker is considered to be 100 ms.
The BFP reset time is maximum 15 ms.
The margin should be chosen to about 2 cycles. This gives about 155 ms minimum setting
of back-up trip delay
The fault
occurs
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Figure 21:
3.1.11 Calculating settings for breaker failure protection LV-side
CCRBRF
The breaker failure protection can use either contact function in the circuit breaker or current
measurement to detect correct breaker function. For line protections it seems to be most
suitable function is to use current measurement breaker check.
Transformer protection RET650
Application manual
1 out of 3 : at least one of the three-phase current shall be larger than the set level to
detect failure to break
1 out of 4 : at least one of the three-phase current and the residual current shall be
larger than the set level to detect failure to break
2 out of 4 : at least two of the three-phase current and the residual current shall be
larger than the set level to detect failure to break As the residual current protection
is one of the protection functions to initiate the breaker failure protection the
1 out of 4 is chosen.
setting
IP> to 20 % of IBase
IN> to 20 % of IBase
t1 to 0
t2 to 0.17 s
t2 .
Protection
operate time
Normal t
cbopen
Retrip delay t1
Trip and Start
BFP
Overexcitation protection characteristics
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IBase .
t after re-trip
cbopen
t
BFPreset
Minimum back-up trip delay t2
Critical fault clearance time for stability
RET650 setting examples
Margin
Time
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Section 3
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