CM
For all characteristics, allowance must be made for the accuracy of the test equipment being
used.
Characteristic
Operating time at twice current setting and time
multiplier/time dial setting of 1.0
Nominal (seconds) Range (seconds)
DT
[: Ι>1 Time Delay] setting
Setting ±2%
IEC S Inverse 10.03 9.53 – 10.53
IEC V Inverse 13.50 12.83 – 14.18
IEC E Inverse 26.67 24.67 – 28.67
UK LT Inverse 120.00 114.00 – 126.00
IEEE M Inverse 0.64 0.61 – 0.67
IEEE V Inverse 1.42 1.35 – 1.50
IEEE E Inverse 1.46 1.39 – 1.54
US Inverse 0.46 0.44 – 0.49
US ST Inverse 0.26 0.25 – 0.28
TABLE 7: CHARACTERISTIC OPERATING TIMES FOR
Ι
>1
Re-perform the tests for the function I>2.
Upon completion of the tests any current differential, overcurrent, earth fault, breaker fail or
supervision elements which were disabled for testing purposes must have their original
settings restored in the CONFIGURATION column.
6.3.3 Breaker Failure Protection
6.3.3.1
Separate external 50BF protection to the busbar protection
P3751ENa
PU4
PU5
PU3
PU1
PU2
CB Fail
External Fault
FIGURE 9: SEPARATE EXTERNAL 50BF PROTECTION TO THE BUSBAR PROTECTION
For example, as shown in the Figure 9, we simulate a CB fail in feeder 1 (PU1). Therefore,
we energise the opto input “External CB Fail” of the PU1 and we check that the central unit
issues a tripping order to PU2 and PU3.
Note: If the I>BB or IN>BB are enabled in menu “Busbar Trip Confirm” in
Peripheral Unit, the CB fail trip command issued by the Central Unit
will be confirmed by a measured phase currents or neutral currents
greater than I>BB (Phase) or IN>BB (Earth).
For example, PU2 and PU3 will operate only if the phase currents > I>BB else the local trip
will be not confirmed.
The trip of the backup phase overcurrent or earth fault overcurrent protection initiates, as
described above, the timers tBF3 and tBF4.
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