Application - ABB REF601 Product Manual

Feeder Protection
REF601 IEC
Product Version: 1.0

3. Application

The REF601 is a protection relay aimed at pro-
tection and control of incoming and outgoing
feeders in MV distribution substations. The relay
can be applied for the short-circuit, over cur-
rent and earth-fault protection of incoming and
outgoing feeders in isolated neutral, resonant
earthed, solidly earthed and resistively earthed
power systems.
The relay is well-matched for mounting on the
circuit breakers VD4 & HD4. Along with sensors,
it will be a part of ABB's offering of integrated
apparatus. The relay has small mounting depth
and does not have any loose mounting acces-
sories while the press-fit mounting arrangement
makes it suitable for quick and easy installation
on switchgear panels too.
4. Sensor technology
Sensors based on alternative principles have
been introduced as successors to instrument
transformers in order to obtain equipment size
reduction, performance improvement and better
standardization. ABB's offering of two sensors,
KECA and KEVCR; employ the Rogowski coil
principle for measurement of current. Albeit this
principle is far from new, now it is possible to
exploit the advantages 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
transformer. However, the output signal from the
Rogowski coil is not current, but a voltage. Due
to absence of ferromagnetic core, the sensor is
linear up to the highest currents.
The wide measurement range of sensors with
high accuracy eliminates the need for high
variants of conventional instrument transformers,
resulting in simplified engineering, logistics and
reduced inventory. The low level voltage signals
and integrated secondary cables contribute to
easy and fast installation with enhanced safety.
4
5. Control
The relay offers control of one circuit breaker with
dedicated push-buttons for opening and closing.
It includes two binary inputs and two outputs for
remote breaker control.
6. Measurement
The relay continuously measures phase currents
and earth current. Earth current can be measured
either by internal calculation or by external core
balance current transformer input. Although the
sensor eliminates the need for providing CT's with
various ratio's, the relay has provision for select-
ing either of the four nominal primary currents.
Thus allowing setting to be done in terms of se-
lected nominal primary current and gives a sense
of continuity with legacy products. During ser-
vice, the default view of display shows the most
loaded phase current in primary terms (Amps)
and the earth current in terms of nominal value.
The values measured can be accessed locally via
the user interface on the relay or remotely via the
communication interface of the relay.
To maintain the measurement accuracy of the
overall protection system, the sensor calibration
constants available on the rating plate of sensors
can be programmed to the relay.
7. Event log
To collect sequence-of-events (SoE) information,
the relay incorporates a non-volatile memory to
store five event logs. Each event log includes a
snapshot of Analog values, Protection operation
status, Binary I/O status and Relay fault code. The
event logs are stored sequentially, the most recent
being first and so on. The non-volatile memory
retains its data also in case the relay temporarily
loses its auxiliary supply.
The event log facilitates detailed pre- and post-
fault analyses of feeder faults and disturbances.
ABB