ABB REJ 521 - REJ 521 Earth-Fault Relay: Introduction; About the REJ 521 Operators Manual; REJ 521 Relay Use and Application; Key Features of the REJ 521 Relay

1MRS 752179-MUM
Earth-Fault Relay
Operator’s Manual
REJ 521
5
1. Introduction
1.1. About this manual
This manual provides the user with basic information on the earth-fault relay REJ
521 and presents detailed instructions on how to use the Human-Machince Interface
(HMI) of the relay, also known as the Man-Machine Interface (MMI). In addition to
the instructive part, a short chapter on the service of the relay has been included.
1.2. The use of the relay
The REJ 521 is intended for non-directional earth-fault protection in medium
voltage distribution networks but can also be used for protection of generators,
motors and transformers.
The REJ 521 is based on a microprocessor environment. A self-supervision system
continuously monitors the operation of the electronics and the software.
The HMI includes a Liquid Crystal Display (LCD) which makes the local use of the
relay safe and easy.
Local control of the relay can be carried out using 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 the fibre-optic bus.
1.3. Features
• Low-set non-directional earth-fault stage with definite-time or indefinite
minimum time (IDMT) characteristic
• High-set non-directional earth-fault stage with instantaneous or definite-time
characteristic
• Circuit-breaker failure protection unit (CBFP)
• Disturbance recorder
• recording time up to 28 seconds
• triggering by a start or a trip signal from either of the two protection stages and/
or by a binary input signal
• records the analogue channel and five digital channels
• adjustable sampling rate
• Non-volatile memory for
• up to 60 event codes
• setting values
• disturbance recorder data
• recorded data of the five last events with time stamp
• number of starts for each stage
• alarm indication messages and LEDs showing the status at the moment of
power failure
• one accurate current input
• Galvanically isolated binary input with a wide input voltage range