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ABB Substation Automation
Products and Systems
3
3.1
3.2
1MRS750940-MUM
Technical Reference Manual
Instructions
Application
The overcurrent relay REJ 523 is a secondary relay that is connected to the current
transformers of an object to be protected. The three-phase overcurrent unit
continuously measures the phase currents of the object. On detection of a fault the
relay starts, trips the circuit breaker, provides alarms, records fault data etc., in
accordance with the application and the configured relay functions.
The overcurrent unit includes two protection stages: a low-set stage I> and a high-set
stage I>>. If the high-set stage is given a setting within the lower part of the setting
range, the relay module will contain two nearly identical operation stages. In this case
the relay can be used in two-stage load shedding applications.
The protection functions are independent of each other and have their own setting
groups and data recording. The overcurrent protection function uses conventional
current transformer measurement.
Output contact matrix allows any start or trip signal from the protection stages to be
routed to the desired output contact.
Requirements
When the protection relay is operating under conditions specified below (see also
"Technical data"), the relay is practically maintenance-free. The relay includes no
parts or components subject to abnormal physical or electrical wear under normal
operating conditions.
Environmental conditions
•
Specified ambient service temperature range
•
Temperature influence on the operating values of the
relay within the specified ambient service temperature
range
•
Transport and storage temperature range
REJ 523
-10...+55 °C
0.1% / °C
-40...+70 °C
7
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