Indicator Leds And Alarm Indication Messages - ABB REU 523 Technical Reference Manual

1MRS 750942-MUM
4.1.5.
Combined Overvoltage and Undervoltage Relay
Technical Reference Manual
Table 4.1.4.7-2 Stages U< and U<<
Feature
Set start value
• at definite-time and IDMT
characteristic
Start time, typical
Time/voltage characteristics
• definite time
operate times t< and t<<
• IDMT
time multipliers k< and k<<
Resetting time, typical
Drop-off/pick-up ratio
Operate time accuracy at
definite-time characteristic
Operate time accuracy at
IDMT characteristic
Operation accuracy
• definite-time and IDMT
characteristic
• positive-phase-sequence with
definite-time and IDMT
characteristic
1)
The stage can be set out of operation in SGF. This state will be indicated by dashes on the LCD and
by "999" when parameters are read via the SPA bus.

Indicator LEDs and alarm indication messages

The operation of the REU 523 can be monitored by means of three indicators on the
front panel of the relay: a green READY indicator LED, a yellow START indicator
LED and a red TRIP indicator LED (refer to the Operator's Manual for a more
thorough presentation).
In addition, in case of an alarm from a protection stage, a text message will appear
on the LCD.
The messages on the LCD have a certain priority order. If different types of
indications are activated simultaneously, the message with the highest priority will
appear on the LCD.
The priority order of the messages:
1. CBFP
2. TRIP
3. START
Stage U<
0.30...1.20 x U
n
80 ms
0.10...600 s
C-curve
0.10...2.00
70 ms
1.01...1.05
±2% of the set start value
or
±25 ms
±25 ms or the accuracy
appearing when the
measured voltage varies
±3%
±1.5% of the set start value ±1.5% of the set start value
REU 523
Stage U<<
)
)
1
0.30...1.20 x U
n
50 ms
0.10...600 s
C-curve
0.10...2.00
70 ms
1.03
±2% of the set start value
or
±25 ms
±25 ms or the accuracy
appearing when the
measured voltage varies
±3%
±5% of the set start value
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