Protection - ABB REU 523 Technical Reference Manual

REU 523
4.1.4.
4.1.4.1.
4.1.4.2.
14
Combined Overvoltage and Undervoltage Relay
Technical Reference Manual

Protection

Block diagram
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Overvoltage unit
When the voltage values exceed the set start value of low-set stage U>, the
overvoltage unit will start to deliver a start signal after a ~ 60 ms' start time. When
the set operate time at definite-time characteristic or the calculated operate time at
IDMT characteristic elapses, the overvoltage unit will deliver a trip signal.
When the voltage values exceed the set start value of high-set stage U>>, the
overvoltage unit will start to deliver a start signal after a ~ 50 ms' start time. When
the set operate time at definite-time characteristic or the calculated operate time at
IDMT characteristic elapses, the overvoltage unit will deliver a trip signal.
It is possible to block the tripping of an overvoltage stage by applying an external
binary input signal to the relay.
The high-set stage can be set out of operation. This state will be indicated by dashes
on the LCD and by "999" when the set start value is read via serial communication.
1MRS 750942-MUM