Calculating Settings For Hv-Side Breaker Failure Protection Ccrbrf (50Bf) - ABB REC650 Applications Manual

1MRK 511 286-UUS A
3.1.8
Application manual
Calculating settings for HV-side breaker failure protection,
CCRBRF (50BF)
The breaker failure protection can use either the position indication of the circuit breaker
or measure the current going through the CT in order to detect correct breaker functioning.
For transformer protections it is most suitable to use current measurement as a circuit
breaker failure check.
1. Set GlobalBaseSel to 1
The (HV) winding data should be related to Global base 1.
2. Set FunctionMode to Current
3. Set BuTripMode to 1 out of 4
The current measurement function uses the three-phase currents from the line CT
and either, a measured residual current or a calculated 3I0. Based on this analogue
data one of the following rules can be chosen in order to determine a breaker failure:
• 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 setting 1 out of 4 is chosen.
4. Set Pickup_PH to 20 % of IBase
Pickup_PH should be set lower than the smallest current to be detected by the
differential protection which is set 30% of IBase.
5. Set Pickup_N to 20 % of IBase
Pickup_N 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 t1 to 0
7. Set t2 to 0.17 s
The delay time of the breaker failure protection (BuTrip) is chosen according to
figure 13.
The maximum opening time of the circuit breaker is considered to be 100 ms.
The breaker failure protection BFP maximum reset time is 15 ms.
A margin of about 2 cycles should be chosen. This gives a minimum setting of back-
up trip delay t2 of about 155ms.
Section 3
REC650 setting examples
57