Inverse Definite Minimum Time Characteristics - ABB REF 610 Technical Reference Manual

1MRS755310
5.1.4.9.
Feeder Protection Relay
Technical Reference Manual
Lockout of the auto-reclose function
The lockout signal indicates whether the AR function is ready for shot initiation.
The AR function will be locked out in any of the following situations:
The AR function generates a definite trip alarm
*
The AR function is inhibited
*
Circuit-breaker closing fails
*
Manual circuit-breaker closing is detected
*
The lockout signal is reset and the AR function ready for shot initiation on
expiration of the set reclaim time. The set reclaim time starts when the definite trip
alarm signal, the AR inhibition signal or the CB reclosing failed signal has
been reset or the circuit breaker closed, depending on the reason for the AR function
being locked.

Inverse definite minimum time characteristics

The low-set overcurrent and earth-fault stages can be given an inverse definite
minimum time (IDMT) characteristic. At IDMT characteristic, the operate time of
the stage is dependent on the current value: the higher the current value, the shorter
the operate time.
The relay provides nine IDMT characteristics, of which four comply with the IEC
60255-3 and three with the IEEE C37.112 standard. Two are special characteristics
according to ABB praxis and are referred to as RI and RD.
The time/current characteristics can be selected either via the HMI or the SPA bus as
follows:
Table 5.1.4.9.-1 Time/current characteristic settings
Value Time/current characteristic
0 Definite time
1 IEC Extremely inverse
2 IEC Very inverse
3 IEC Normal inverse
4 IEC Long-time inverse
5 RI-type
6 IEEE Extremely inverse
7 IEEE Very inverse
8 IEEE inverse
9 RD-type (RXIDG)
IDMT characteristics according to IEC 60255-3
The relay provides four time/current curve groups which comply with the
IEC 60255-3 standard: normal inverse, very inverse, extremely inverse and long-
time inverse. The relationship between time and current is expressed as follows:
REF 610 REF 610
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