Month: July 2025

Description 

The REF601 is a dedicated feeder protection and control relay. 

The REJ601 is an overcurrent protection relay without breaker control. 

These relays are intended for the protection of utility 

substations and industrial power systems within primary and 

secondary distribution networks. They are members of ABB’s 

Relion® product family and part of its 605 series.

These relays, provide an optimized composition of protection, 

monitoring and control functionality in one unit, with the best 

performance usability in its class and are based on ABB’s indepth knowledge of protection and numerical technology

Relay functions

The REF601 and REJ601 can be pre-configured which facilitates easy and fast commissioning of switchgear. 

To emphasize the simplicity of using these relays, only application specific parameters need to be set within the relay’s intended area of application. 

The standard signal configuration can be altered by LHMI (local human-machine interface).

Basic Functions

Self Supervision

The IED is provided with an extensive self-supervision system which continuously 

supervises the software and the electronics. It handles run-time fault situations and 

informs the user about an existing fault via the LHMI and the communication. 

When in an IED internal fault is detected, the green Ready LED ceases to glow and the 

self-supervision output contact is activated. Internal fault indications have the highest 

priority on the LHMI. None of the other LHMI indications can override the internal fault 

indication. An indication about the fault is also shown as a message on the LHMI. 

The text IRF with an additional text message, a code is shown to indicate the fault type. 

The user can try to eliminate the fault by restarting the IED. 

If the fault is still found, the IED stays in internal fault mode. 

All other output contacts are released and locked for the internal fault. 

The IED continues to perform internal tests during the fault situation.

If an internal fault disappears, the green Ready LED starts glowing and the IED 

returns to the normal service state. The fault indication message remains on the LCD until manually cleared.

The self-supervision signal output operates on the closed circuit principle.

Under normal conditions the relay is energized and the contact gap 5-6 in connector XK2 is closed.

If the auxiliary power supply fail or an internal fault is detected, the contact gap 5-6 is opened.

Overview

REF601 CEI overview

REF601 is a dedicated feeder protection relay, intended for the protection, measurement and supervision of utility substations and industrial power systems.

Engineered from the ground up, the relay is inspired by and is compatible with the Rogowski coil sensor for current measurement. 

The new feeder protection relay is designed to unleash the advantages of current sensors for protection and control in medium voltage applications.

The REF601 features compact size and ease of use. 

The features include:

. Sensor input for phase current 

. External CBCT input for earth current 

. Three-stage overcurrent protection 

. Two-stage earth-fault protection 

. Magnetizing inrush detection 

. Control of circuit breaker 

. Local and remote control 

. Five event logs 

 . Two fault records of analogue value 

. Non-resettable trip counter 

. On-line measurements 

. Comprehensive local HMI 

. Universal auxiliary supply rating 

. Circuit breaker or panel mounting 

. Optional Modbus communication 

. Non-volatile memory 

. Access control 

. Self-supervision 

. Built-in test functionality

Introduction

This manual

This manual contains application and functionality descriptions and connection

diagrams, input and output signals, setting parameters and technical data. The

manual can be used as a technical reference during the engineering phase,

installation and commissioning phase, and during normal service. The manual

can also be used when calculating settings. Instructions on how to operate the IED

during normal service once it has been commissioned and it can be used to fi nd

out how to handle disturbances or how to view calculated and measured network

data in order to determine the cause of a fault

Intended Audience

This manual addresses system engineers, installation and commissioning personnel, 

who use technical data during engineering, installation and commissioning, and

in normal service. system engineer must have a thorough knowledge of protection

systems, protection equipment, protection functions and the confi gured functional

logics in the IEDs. The installation and commissioning personnel must have a basic

knowledge in handling electronic equipment.

This manual addresses Protection and control engineer responsible for planning, preengineering and engineering. 

The protection and control engineer must be experienced

in electrical power engineering and have knowledge of related technology, such as

communication and protocols.

The manual also addresses the operator, who operates the IED on a daily basis. The

operator must be trained in and have a basic knowledge of how to operate protection

equipment. The manual contains terms and expressions commonly used to describe

this kind of equipment.

Principle of Operation

REF601 has earth fault protection with low set and high set module.

Earth fault modules operate the protection as soon as fault current exceeds the set value of current.

It supports both DMT and IDMT timing while highset supports to DMT timings.

As the fault current exceeds the set value, trip time counting is started and start LED on front panel of relay glows ON.

If fault current falls down below the drop-off value of set current for 40 ms before trip time gets complete,

start LED will be turned off and trip count will become zero.

Trip time will start from zero next time when the fault current exceeds the set value again.

After a healthy trip, Start LED will be turned off and again

if fault current exceeds threshold, start LED will be turned ON again.

In case of healthy fault generation, after trip time get elapsed relay generates the trip

command which operates the Trip relay contacts as per user selected configuration.

Two LED indications on front plate of relay i.e.

Trip (common trip indication) and Trip Io and one signaling contact (XK2.1 –XK2.2) will

also be generated for user as Trip indication.

Protection Function

Three Phase Current Protection

Functionality

The three-phase overcurrent protections is used as single-phase, two-phase

or three phase non-directional overcurrent and short-circuit protection for feeders.

The function starts when the current exceeds the set limit. 

The operate time characteristics for low stage is both DMT and IDMT and high stage is definite time (DT) definite minimum. 

The instantaneous stage always operates with the DT characteristic.

In the DT mode, the function operates after a predefined operate time and resets when the fault current disappears. 

The IDMT mode provides current-dependent timer characteristics.

Earth Fault Protection

Functionality

The earth-fault function is used as non-directional earth-fault protection for feeders.

The function starts and operates when the set current exceeds the set limit.

The relay can measure earth current by internal calculation (IEC variant only) and

also by external core balance current transformer input.

Separate earth fault input is available in relay which can be connected to corebalance current transformer of 1A secondary.

The operate time characteristic for low stage has both DT and IDMT and high stage has only

definite time (DT) .. In the DT mode, the function operates after a predefined

operate time and resets when the fault current disappears.

Principle of Operation

The three-phase overcurrent unit continuously measures the phase currents of the protected object. 

On detection of a fault the relay starts, trips the circuit breaker, records fault data etc. in accordance with the application.

REF601 has overcurrent protection with low set, high set and very high set module.

The product support both DMT and IDMT times in low set (I>) while high set (I>>) and Very high set (I>>>) supports to DMT timings. 

As the fault current exceeds the set value, trip time counting is started and start LED on front panel of relay glows ON. 

If fault current falls down below the drop off value of set current for 40 ms before trip time gets complete, start LED

will be turned off and trip count will become zero. 

Trip time will start from zero for next time when the fault current exceeds the set value again.

After a healthy trip, Start LED will be turned off and again if fault current exceeds threshold, start LED will be turned ON again.

In case of healthy trip, after trip time get elapsed relay generates the trip command which operates the Trip relay contacts as per user selected

configuration. Two LED indications on front plate of relay i.e. Trip (common trip indication) and Trip Ip and one signaling contact (XK2.3 –

XK2.4) will also be activated for user as Trip indication.

Optional function

Communication on MODBUS RTU Protocol

Other Functions

Self Supervision

The IED is provided with an extensive self-supervision system which

continuously supervises the software and the electronics.

It handles runtime fault situations and informs the user about an existing fault via the LHMI.

When in an IED internal fault is detected, the green Ready LED ceases to

glow and the self-supervision output contact is activated. Internal fault

indications have the highest priority on the LHMI. None of the other

LHMI indications can override the internal fault indication. An indication

about the fault is also shown as a message on the LHMI. The text IRF with

an additional text message, a code is shown to indicate the fault type.

The user can try to eliminate the fault by restarting the IED. If the fault is

still found, the IED stays in internal fault mode. All other output contacts

are released and locked for the internal fault.

The self-supervision signal output operates on the closed circuit principle.

Under normal conditions the relay is energized and the contact gap 5-6 in

connector XK2 is closed. If the auxiliary power supply fail or an internal

fault is detected, the contact gap 5-6 is opened.

Overview

REF601 is a dedicated feeder protection relay, intended for the protection

and control of utility substations and industrial power systems. 

The relay is compatible with the Rogowski coil sensor for current measurement. 

The feeder protection relay REF601 is designed to unleash the advantages of

current sensors for protection and control in medium voltage applications.

The REF601 features compact size and ease of use. 

The features include:

Sensor input for phase current measurement

Earth current measurement internally or externally through CBCT

Three-stage overcurrent protection

Two-stage earth-fault protection

Inrush detection for stability during transformer charging

Local and remote control of circuit breaker

Trip Circuit Supervision

Lockout function

100 event logs

Two analogue fault records

Non-resettable trip counter

On-line current measurements in primary value

Comprehensive local HMI

Universal auxiliary supply

Compact design suitable for circuit breaker or panel mounting

Optional MODBUS RTU communication

Non-volatile memory for setting and fault records

Self-supervision

User selectable rated frequency 50 / 60 Hz

Operation Functionality

Relay functions

REF601 offers pre-configured functionality which facilitates easy and fast

commissioning of switchgear. To emphasize the relay’s simplicity of usage,

only application specific parameters needs to set within the relay’s intended area of application.

The settings can be changed by LHMI (local human-machin interface) or

through optional communication interface MODBUS master with setting capability.

The relay offers protection, control, measurement and condition monitoring functionality.

Intended audience

This manual addresses system engineers, installation and commissioning

personnel, who use technical data during engineering, installation and

commissioning, and in normal service. system engineer must have a

thorough knowledge of protection systems, protection equipment,

protection functions and the configured functional logics in the IEDs.

The installation and commissioning personnel must have a basic

knowledge in handling electronic equipment.

This manual addresses Protection and control engineer responsible for

planning, pre-engineering and engineering. The protection and control

engineer must be experienced in electrical power engineering and have

knowledge of related technology, such as communication and protocols.

The manual also addresses the operator, who operates the IED on a daily

basis. The operator must be trained in and have a basic knowledge of

how to operate protection equipment. The manual contains terms and

expressions commonly used to describe this kind of equipment.