ABB REX 521 - Iub; 3 Ith

98
1MRS751802-MUM
Protection Relay
Technical Reference Manual, Standard Configurations
REX 521
7.1.8. Iub>
The phase discontinuity protection function block Iub> is designed to be used for
protection against broken phase conductors in distribution networks. Definite-time
(DT) characteristic is always used.
Fig. 7.1.8.-1 Function block symbol of Iub>
7.1.9. 3Ith>
The three-phase thermal overload protection function block 3Ith> is designed for the
thermal protection of three-phase power cables and overhead lines.
Fig. 7.1.9.-1 Function block symbol of 3Ith>
Phase discontinuity protection, Iub>
Start unbalance
Operate time
Operation mode
10.0…95.0%
1.0…300.0 s
Not in use
Definite time
Operation accuracy
Start time
Reset time
Reset ratio, typically
Retardation time
Operate time accuracy in DT mode
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
BS1
BS2
GROUP
RESET
START
TRI
P
CBF
P
Iub>
CBFP
3∆I>
3Ithdev>
3
BLOCK
RESET
START
TRIP
CBFP
EN_RESTART
J>
Dev
CBFP