Monitoring - ABB REU 523 Technical Reference Manual

REU 523
4.1.4.
28
Combined Overvoltage and Undervoltage Relay
Technical Reference Manual
Table 4.1.3.7-2 Stages U< and U<<
Feature
Start voltage
• at definite-time and inverse-time
characteristics
Start time, typical
Time/voltage characteristic
• definite time
• operate times t< and t<<
• inverse-time characteristic
• time multipliers k< and k<<
Reset time
Drop-off/pick-up ratio
Operate time accuracy at definite-
time mode
Operate time accuracy at inverse-
time mode
Operation accuracy
• definite-time and inverse-time
characteristic
• positive-phase-sequence with
definite-time and inverse-time
characteristic
1)
Note!
The reset time is normally 70 ms. In case the measured voltage that caused the activation of the
output relay falls below the set start voltage value within less than the start time of the protection
function stage added with the set minimum pulse length for the activated relay, the reset time
depends on the selected minimum pulse length.

Monitoring

The function of the relay can be monitored with the help of three indicators on the
relay front panel: a green READY LED, a yellow START LED and a red TRIP
LED.
In addition, in case of an internal fault or an alarm from the protection stages, a text
message appears on the display.
The messages on the LCD have a certain priority order. If different types of
indications are activated simultaneously, the message with the highest priority
appears on the display.
The priority order of the messages:
1. Internal fault
2. Trip, CBFP
3. Start
Stage U<
0.30...1.20 x U
n
80 ms
0.10...600 s
C-curve
0.10...2.00
1)
70 ms
1.01...1.05
±2 % of set value or
±25 ms
±25 ms or the accuracy
appearing when the
measured voltage varies ±3
%
±1.5% of set value
1MRS 750942-MUM
Stage U<<
and ∞
0.30...1.20 x U
n
50 ms
0.10...600 s
C-curve
0.10...2.00
1)
70 ms
1.03
±2 % of set value or
±25 ms
±25 ms or the accuracy
appearing when the
measured voltage varies ±3
%
±1.5 % of set value
±5% of set value
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