Calculating Settings For Breaker Failure Protection 3-Phase Activation And Output Ccrbrf (50Bf) - ABB Relion 650 Series Applications Manual

1MRK 505 287-UUS B
V>Alarm = VR_unb = 30 V
We suppose that: – the magnetizing current of the CT at UR_unb is 6 mA, with an angle -60°; –
the current that is drawn by the non-linear resistor at UR_unb is about 1 mA. So, the
sensitivity in primary current is:
IP = 600/1 * (0,02 /_0° + 0,001 /_0° + 4* 0,006 /_-60°) = 20 A
The sensitivity should allow the detection of the open CT on the smallest object in normal
load condition.
6. Set
3.1.6 Calculating settings for breaker failure protection 3-phase
activation and output CCRBRF (50BF)
The breaker failure protection can use either the contact check criterion or the current
measurement criterion to detect breaker failure. The breaker failure protection supervises the
bus-coupler circuit breaker in the present application. In that case the most suitable criterion is
the one based on current measurement.
1. Set
The settings are made in primary values. The values of the base primary quantities are set in
Global base 1.
2. Set
3. Set
In the current measurement the three-phase current are used. It is also possible to measure
the residual current (analogue input 4). The following mode to detect failure of the circuit
breaker can be chosen:
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.
In the present example the busbar protection initiates the breaker failure protection. The
setting
4. Set
The fault current through the buscoupler depends on the particular configuration of the
substation after the trip of the busbar protection and opening of the circuit breakers of the
relevant feeders. Hence, the setting of the breaker failure protection is very sensitive.
5. Set
The fault current through the buscoupler depends on the particular configuration of the
substation after the trip of the busbar protection and opening of the circuit breakers of the
relevant feeders. So the setting of the breaker failure protection shall be very sensitive.
6. Set the re-trip time delay
7. Set
The delay time of the breaker failure protection (BuTrip) is chosen according to figure 7.
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Busbar protection REB650
Application manual
tAlarm to 15 s
GlobalBaseSel to 1
Function mode to Current
BuTripMode to 1 out of 4
1 out of 4 is chosen.
Pickup_PH to 10 % of the base current.
Pickup_N to 10 % of the base current.
t1 to 0 (The re-trip output TRRET is not used).
t2 to 0.15 s
The maximum open time of the circuit breaker is considered to be 100 ms.
The CCRPRF (50BF) reset time is 10 ms max.
The margin should be chosen to about 2 cycles. This gives about 150 ms minimum
setting of backup trip delay
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t2 .
Section 3
REB650 setting examples
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