ABB REC650 Applications Manual page 65

1MRK 511 286-UUS A
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.
There is no residual current measurement protection on the 22 kV side of the
transformer. Therefore 1 out of 3 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 25 % of IBase.
5. Set the re-tip time delay t1 to 0 s
6. Set t2 to 0.17 s
The delay time of the breaker failure protection (BuTrip) is chosen according to
figure 13.
The maximum open time of the circuit breaker is considered to be 100 ms.
The 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.
Protection
operate time
Retrip delay t1
The fault
occurs
Trip and Start
BFP
EN05000479 V1 EN
Figure 14: Time sequences for breaker failure protection setting
Normal t
cbopen
t after re-trip
cbopen
Minimum back-up trip delay t2
Critical fault clearance time for stability
Section 3
REC650 setting examples
t
BFPreset
Margin
Time
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