ABB
4
GUID-89A9F7DF-FB82-4E8D-B449-7C0BB51C1DCA V1 EN
1MDB07207-YN
Feeder Protection
REF601
Product version: 2.0
3. Protection functions
REF601 offers three-stage phase segregated
overcurrent and two-stage earth-fault protection
functions. The transformer inrush detector function
is incorporated to prevent unwanted trippings due
to energizing of transformers.
The low-set stages for overcurrent and earth-fault
protection are equipped with selectable charac-
teristics - Definite time (DT) and Inverse definite
minimum time (IDMT) . The relay features stand-
ard IDMT characteristics – Normal Inverse (NI),
Very Inverse (VI), Extremely Inverse (EI), Long-time
Inverse (LI) and a special characteristic RI inverse
(RI) for better co-ordination with rest of the network
protection.
Figure 1. Protection function overview of REF601
with earth current measurement by internal
calculation
Figure 2. Protection function overview of REF601
with earth current measurement by exter-
nal core-balance current transformer
4. Application
The REF601 is a protection relay aimed at protec-
tion and control of incoming and outgoing feeders
in MV distribution substations. The relay can be
applied for the short-circuit over current and earth-
fault protection of overhead lines and cable feeders
of distribution and sub-distribution network.
The relay is well-matched for mounting on the ABB
circuit breakers VD4 & HD4. Along with sensors, it
will be a part of ABB’s offering of integrated appara-
tus. The relay has small mounting depth and does
not have any loose mounting accessories while the
press-fit mounting arrangement makes it suitable
for quick and easy installation on switchgear panels
too.
5. Sensor technology
S
ensors based on Rogowski coil principle have
been introduced in order to get benefit of improved
performance like saturation of conventional current
transformer and equipment size reduction. ABB is
offering two types of sensors - KECA and KEVCR
which employees the Rogowski coil principle for
measurement of current. Albeit this principle is far
from new, now it is possible to exploit the advan-
tages of sensor with the advent of numerical relays
like REF601.
Rogowski coil is a toroidal coil without an iron core,
placed around the primary conductor in the same
way as the secondary winding in a current trans-
former. However, the output signal from Rogowski
REF601
Lockout
relay
86
50-1
50-2
50N
Lockout
relay
86
REF601
50-1
50-2
50N
Summary of Contents for REF601
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