Blocking: To achieve fast activation for blocking purpose with harmonic OC stage the harmonic
stage may activate if rapid load change or fault situation occur. Intentional activation lasts for
about 20 ms if harmonic component is not present. Harmonic stage stays active in case the
harmonic content is above the pick-up limit.
Tripping: When using harmonic OC –stage for tripping make sure that the operation time is set
to 20 ms (DT) or higher to avoid nuisance tripping due the above mentioned reason.
9.2.1.7. Circuit breaker failure protection (50BF/52BF) CBFP
Table. 9.2.1.7. - 268. Breaker failure (50BF/52BF) technical data
Input signals
Input magnitudes
Phase currents, I01, I02 I0Calc fundamental freq RMS
Digital input status, Digital output status
Pick-up
Pick-up current setting
-IL1…IL3
-I01, I02, I0Calc
0.10…40.00 x In, setting step 0.01 x In
0.005…40.00 x In, setting step 0.005 x In
Inaccuracy
-Starting phase current (5A)
-Starting I01 (1 A)
-Starting I02 (0.2 A)
-Starting I0Calc (5 A)
±0.5 %I
SET
or ±15 mA (0.10…4.0 x I
SET
)
±0.5 %I0
SET
or ±3 mA (0.005…10.0 x I
SET
)
±1.5 %I0
SET
or ±1.0 mA (0.005…25.0 x I
SET
)
±1.0 %I0
SET
or ±15 mA (0.005…4.0 x I
SET
)
Operation time
De nite time function operating time setting
0.050…1800.000 s, setting step 0.005 s
Inaccuracy
-Current criteria (Im/Iset ratio 1.05
→
)
-DO or DI only
±1.0 % or ±55 ms
±15 ms
Reset
Reset ratio
97 % of pick-up current setting
Reset time
<50 ms
9.2.1.8. Restricted earth fault / Cable end differential (87N) Iod>
Table. 9.2.1.8. - 269. Restricted earth fault / Cable end differential (87N) technical data
Input signals
Input magnitudes
Phase currents, I01, I02 fundamental frequency RMS
Calculated bias and residual differential currents
Pick-up
Operating modes
Restricted earth fault
Cable end differential
Characteristics
Biased differential with 3 settable sections and 2 slopes
Pick-up current sensitivity setting
Slope 1
Slope 2
BIAS (Slope 1&2)
0.01…50.00% (In), setting step 0.01 %
0.00…150.00%, setting step 0.01%
0.00…250.00%, setting step 0.01%
0.01…50.00 x In, setting step 0.01
Inaccuracy
- Starting
±3% of set pick-up value > 0.5 x In setting.
±5 mA < 0.5 x In setting
Operation time
Instant operation time
1.05 x Iset
<30ms
Reset
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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