ABB REX 521 Feeder Protection Relay

Provides basic protection for busbars and feeders in utility substations and industrial distribution systems

Products not used since 2012

The feeder protection relay REX 521 is designed for protection, control, measurement and monitoring in medium-voltage grids, as well as for the protection of medium and large three-phase AC motors in circuit breaker-controlled motor drives.

and for the protection of medium and large three-phase AC motors in circuit breaker controlled motor drives.

Typical applications include inlet and outlet feeders and motor feeders as well as substation protection.

In addition, the relays can be used as backup protection for power transformers and as backup protection for high-voltage line protection relays.

The protective relay is equipped with energizing inputs for conventional current and voltage transformers. Hardware versions with current and voltage sensor inputs are also available.

The REX 521 feeder protection relay is further enriched with additional functions to provide your grid with more efficient protection, extended measurement functions, monitoring, control functions and connectivity.

The REX 521 is primarily used in single-bus solutions for various protections using a single circuit breaker.

With pre-fabricated standard configurations, the unit can be used in different types of networks. Typical applications include input and output feeders in radially isolated neutral, resonant grounded, solid grounded and resistance grounded systems.

Scope

Protection, control, measurement and monitoring in medium voltage networks and for the protection of medium and large three-phase AC motors

Product advantages

Multifunctional protection

Product features

energized inputs for conventional current and voltage transformers

Versions with current and voltage sensor inputs also available

Prefabricated, standard configuration

REX 521 Relay Protection Unit

The REX 521 relay protection unit is designed for protection, control, measurement and monitoring of medium voltage networks.

Typical applications include incoming and outgoing feeders and substation protection.

The relay protection unit is equipped with energized inputs for conventional current and voltage transformers.

Hardware versions with current and voltage sensor inputs are also available.

The relay protection unit is based on a multiprocessor environment.

The human-machine interface includes an LCD display with different views for local use and informs the user with prompt messages.

Both hardware and software solutions utilize modern technology.

REX 521 is part of the Distribution Automation substation automation concept and further extends the functionality and flexibility of the concept.

Description

HMI functions

- Buttons for navigation, [C] clear/cancel and [E] enter

- Language selection

- Password-protected set values

- Display backlighting

- Display contrast

- Display test

- Master value selection

- Optically isolated serial communication port

Pushbutton Functions

The HMI includes buttons for operating the relay. A quick touch of the up [↑] or down [↓] arrow buttons

indicates a step up or down in the menu or a minimum step up or down in the parameter setting mode.

- The cursor stops at the first and last lines of the menu; pressing the [↑] button for the first line or the [↓] button for the last line is ignored.

- If [↑] or [↓] is held down all the time, the menu automatically scrolls faster than a single keystroke.