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REJ 523
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Technical Reference Manual
Introduction
About this manual
This manual is intended to provide the user with thorough information on the relay
REJ 523 and its applications. The focus in the manual is on technical description of
the relay.
Instructions for using the MMI are found in a separate "Operator's Manual" and for
installation in "Installation Manual".
The use of the relay
The overcurrent relay REJ 523 is designed to be used for selective short-circuit
protection in medium voltage distribution networks. The protection relay includes a
phase overcurrent unit with flexible tripping and signalling facilities. The overcurrent
relay can also be used in other applications requiring single-, two- or three-phase
overcurrent protection.
The protection relay REJ 523 is based on a microprocessor environment. A self-
supervision system monitors continuously the operation of the microprocessor.
The MMI includes an LCD display which makes the local use of the relay safe and
easy.
Local control of the protection relay can be carried out with a portable computer
connected to the front connector and remote control via the rear connector connected
to the distribution automation system through the serial interface and fibre-optic bus.
Features
• Three-phase low-set overcurrent stage with definite-time or inverse definite
minimum time (IDMT) characteristic.
• Three-phase high-set overcurrent stage with instantaneous or definite-time
characteristic.
• Circuit-breaker failure protection unit (CBFP).
• Disturbance recorder.
• Three accurate current inputs.
• Galvanically isolated binary input with a wide input voltage range.
• All settings can be modified with a personal computer.
ABB Substation Automation
Products and Systems
MRS750940-MUM
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