3Ith - ABB REX 521 Technical Reference Manual, Standard Configurations

1MRS 751802-MUM
7.1.9.
Protection Relay
Technical Reference Manual, Standard Configurations
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3∆I>
CBFP
BS1
START
BS2
TRIP
GROUP
CBFP
RESET
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Phase discontinuity protection, Iub>
Start unbalance
Operate time
Operation mode
Operation accuracy
Start time
Reset time
Reset ratio, typically
Retardation time
Operate time accuracy in DT mode
3Ith>
The three-phase thermal overload protection function block 3Ith> is designed for the
thermal protection of three-phase power cables and overhead lines.
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3
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Cab
CBFP
BLOCK START
GROUP TRIP
RESET CBFP
CU_ALARM
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10.0...95.0%
1.0...300.0 s
Not in use
Definite time
Note! The values below apply when f/fn = 0.95...1.05
±2.5% of set value or ±1% unit
internal time < 95 ms
total time < 100 ms
40...1000 ms (depends on the minimum pulse width set
for the trip output)
0.95
Total time for blocking: < 25 ms
Total time when current drops below start value: < 50 ms
±2% of set value or ±50 ms
REX 521
85