ABB REX 521 Feeder Protection Relay

ABB REX 521 Feeder Protection Relay

Product Overview

REX 521 feeder protection relays are mainly used in medium voltage networks, with protection, control, measurement and monitoring functions. 

In practical use, it can be used for the protection of incoming and outgoing feeders, 

as well as the overall protection of substations to ensure the safe and stable operation of the power system.

Design: Based on a multiprocessor environment, the relay features an easy-to-operate Human Machine Interface (HMI) 

with an LCD display that provides different views and facilitates localized operation by means of indicative messages. 

The relay is integrated into the ABB substation automation system, which further extends the functionality and flexibility of the system.

Product features

A wide range of standard configurations: B01, B02, M01, M02, H01 - H51. 

Taking B01 and B02 as an example, B01 has three-phase, 

three-section non-directional overcurrent protection, three-section non-directional ground fault protection, phase interruption protection, etc., 

which is suitable for simple single-busbar system protection; B02 adds an automatic reclosing function on the basis of B01 to better cope 

with transient faults; and M01 and M02 have added directional ground fault protection, 

which is suitable for systems that have monitoring needs for the direction of faults. 

The H series configurations are more versatile, covering over-voltage, under-voltage, frequency protection and other functions.

Diversified and practical functions: All configurations are generally equipped with basic measurement functions such as current measurement, 

neutral current measurement, current waveform distortion measurement, etc., and they can also calculate the cumulative wear of circuit breakers, 

record transient disturbances, and realize trip circuit monitoring, etc. Some configurations have special functions, such as the H series, 

which is suitable for systems that need to monitor the direction of faults. 

The special functions of some configurations, such as the synchronization/voltage check function of H01, 

negative sequence protection and motor startup monitoring function of H07, meet the special needs of different power systems.

Application Areas

Scenarios for different configurations: Different standard configurations are suitable for different types of network systems; 

B01 and B02 are suitable for basic protection and automatic reclosing scenarios for single busbar systems; 

M01 and M02 are suitable for single busbar systems requiring directional ground fault protection; 

H series configurations are suitable for systems with strict monitoring requirements for overvoltage, undervoltage, 

frequency and other parameters according to their specific functions; 

H07 and H51 can also be used for large or medium-sized systems, and can also be used for large or medium-sized systems, 

H51 can also be used for the protection of large or medium-sized three-phase AC motors.

Design details

Various hardware versions: The hardware versions are divided into four types: Basic, Medium, High and Sensor. 

The versions differ in terms of transformer modules, current transformers, voltage transformers, sensor channels, etc. 

The Basic version is equipped with four 1/5 A current transformers, no voltage transformers and no sensor channels, 

while the Sensor version has a 1/5 A current transformer, a 100 V voltage transformer and three current and three voltage sensor channels, 

which offer a unique advantage in terms of measurement and signal acquisition. 

The Sensor version has 1 1/5 A current transformer, 1 100 V voltage transformer, and 3 current and 3 voltage sensor channels, 

offering unique advantages in measurement and signal acquisition.

Software function integration: Software functions are integrated in the standard configurations, 

with different combinations of functions in the different configurations. NEF1Low, Io>> 51N - 2 NEF1High, Io>>> 51N - 3 NEF1Inst), 

as well as related functions such as measurement, control and condition monitoring.

Detailed technical data

Strict electrical parameters: Rated frequency 50.0/60.0 Hz, current input ratings 0.2A/1A/5A with different thermal and dynamic current capacities. 

Voltage inputs are rated at 100V/110V/115V/120V with corresponding voltage and load requirements. 

Sensor inputs also have specific voltage ranges and impedance requirements.

Other parameter specifications: There are different types of auxiliary power supplies, with provisions for input voltage, voltage variation, load, ripple and so on. 

Digital inputs, signal outputs, power outputs, etc. have defined electrical parameters. 

For environmental conditions, service temperature ranges, transportation and storage temperature ranges, and protection classes are specified. 

In addition, a variety of standard tests and electromagnetic compatibility tests have been passed to ensure reliable product performance.