● = Included
3. Protection functions
REF601/REJ601 offers three-stage overcurrent
and two-stage earth-fault protection functions.
The transformer inrush detector function is
incorporated to prevent unwanted tripping’s due
to energizing of transformers.
The low-set stages for overcurrent and earth-
fault protection are equipped with selectable
characteristics – Definite time (DT) and Inverse
definite minimum time (IDMT). The relay features
standard IDMT characteristics according IEC 61
255-3 and ANSI C37.112, Normal Inverse (NI),
Very Inverse (VI), Extremely Inverse (EI), Long-
time Inverse (LI) respective Moderate inverse,
Normal Inverse, Very inverse, Extremely inverse
and a special characteristic RI inverse (RI) for
better co-ordination with rest of the network.
Further relay offers thermal overload protection
for feeder, cable and transformer, negative
phase sequence protection, phase discontinuity
protection and circuit breaker failure protection.
Relay also has feature of auto-reclose function
for overhead line feeders.
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