Instructions - ABB REU 523 Technical Reference Manual

REU 523
3.
3.1.
3.2.
3.3.
8
Combined Overvoltage and Undervoltage Relay
Technical Reference Manual

Instructions

Application
The over and undervoltage relay REU 523 is a secondary relay which is connected
to the voltage transformers of the object to be protected. The over and the
undervoltage unit continuously measure the fundamental wave of the
phase-to-phase voltages of the object. On detection of a fault, the relay will start, trip
the circuit breaker, provide alarms, record fault data, etc., in accordance with the
application and the configured relay functions.
The overvoltage unit includes low-set stage U> and high-set stage U>> and the
undervoltage unit low-set stage U< and high-set stage U<<. The high-set
undervoltage stage can alternatively be set to evaluate the positive-phase-sequence
voltage. In addition, the high-set undervoltage stage can be configured to evaluate
only one instead of three phase-to-phase voltages.
The protection functions are independent of each other and have their own setting
groups and data recordings. The over and undervoltage functions use conventional
voltage transformer measurement.
An output contact matrix allows start or trip signals from the protection stages to be
routed to the desired output contact.
Requirements
When the REU 523 is operating under the conditions specified below (see also
Technical data), it will be 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 operation accuracy of the
protection relay within the specified ambient service
temperature range
• Transport and storage temperature range
Configuration
Setting and connection example
The appropriate configuration of the output contact matrix enables the use of the
signals from the overcurrent and the earth-fault unit as contact functions. The start
signals can be used for blocking co-operating protection relays, signalling and
initiating autoreclosing.
Figure 3.3.-1 represents the REU 523 with the default configuration.
1MRS 750942-MUM
-10...+55 °C
0.1% / °C
-40...+70 °C