ABB REX 521, Technical Reference Manual, Standard Configurations

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1MRS751802-MUM Protection Relay
Technical Reference Manual, Standard Configurations
REX 521
Three-phase non-directional overcurrent protection, low-set stage, 3I>
Start current
Operate time in DT mode
Time multiplier in IDMT mode
IEEE time dial in IDMT mode
Operation mode
Measuring mode
Drop-off time of the operate time counter
0.10…5.00 x In
0.05…300.00 s
0.05…1.00
0.5...15.0
Not in use
Definite time
Extremely inverse
Very inverse
Normal inverse
Long time inverse
RI-type inverse
RD-type inverse
IEEE Ext. inv.
IEEE Very inv.
IEEE Inverse
IEEE S.T. inv.
IEEE S.T.E. inv
IEEE L.T.E. inv
IEEE L.T.V. inv
IEEE L.T. inv.
Peak-to-peak
Fundamental frequency
0...1000 ms
Note! The values below apply when f/fn = 0.95...1.05
Operation accuracy
Operate time
Reset time
Reset ratio, typically
Retardation time
Operate time accuracy in DT mode
Accuracy class index E in IDMT mode
±2.5% of set value or ±0.01 x In
Injected currents > 2.0 x start current:
internal time < 32 ms
total time < 40 ms
40...1000 ms (depends on the minimum pulse width set
for the trip output)
0.95
< 45 ms
±2% of set value or ±20 ms
Class index E = 5.0 or ±20 ms
Three-phase non-directional overcurrent protection, 3I>> and instantaneous stage,
3I>>>
Start current
Operate time
Operation mode
Measuring mode
Drop-off time of the operate time counter
0.10…40.00 x In
0.05…300.00 s
Not in use
Definite time
Instantaneous
Peak-to-peak
Fundamental frequency
0...1000 ms
Note! The values below apply when f/fn = 0.95...1.05
Operation accuracy
Start time
Reset time
Reset ratio, typically
Retardation time
Operate time accuracy in DT mode
0.1...10 x In: ±2.5% of set value or ±0.01 x In
10...40 x In: ±5.0% of set value
Injected currents > 2.0 x start current:
internal time < 32 ms
total time < 40 ms
40...1000 ms (depends on the minimum pulse width set
for the trip output)
0.95
< 45 ms
±2% of set value or ±20 ms