ABB REF601 Посібник з експлуатації - Сторінка 4

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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.

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