ABB REX 521 Technical Reference Manual, Standard Configurations page 81

1MRS 751802-MUM
7.1.5.
Protection Relay
Technical Reference Manual, Standard Configurations
Three-phase directional overcurrent protection, high-set stage, 3I>>->
Start current
Operate time
Operation mode
Basic angle ϕ
b
Oper. Direction
Earth fault pr.
Nondir. operat.
Measuring mode
Drop-off time of the operate time counter
Operation accuracy
Start time
Reset time
Reset ratio, typically
Retardation time
Operate time accuracy in DT mode
3U> and 3U>>
Abnormal busbar voltages can be caused by faults in the network or a faulty tap
changer or voltage regulator of a power transformer. The function blocks are
designed for the single-phase, two-phase and three-phase overvoltage protection
whenever the DT characteristic or, as concerns 3U>, the IDMT (Inverse Definite
Minimum Time) characteristic is appropriate. Suppression of harmonics is possible.
3U>
BS1
BS2
GROUP START
TRIP
RESET
)LJ  )XQFWLRQ EORFN V\PEROV RI 8! DQG 8!!
0.05...40.00 x In
0.05...300.00 s
Not in use
Definite time
Instantaneous
0...90
Forward
Reverse
Disabled
Enabled
Disabled
Enabled
Mode1 (Phase-to-phase voltages/Peak-to-peak currents)
Mode2 (Phase-to-phase voltages/Fund. freq. Currents)
Mode3 (Phase-to-earth voltages/Peak-to-peak currents)
Mode4 (Phase-to-earth voltages/Fund. freq. Currents)
0...1000 ms
Note! The values below apply when f/fn = 0.95...1.05
Current:
0.1...10 x In: ±2.5% of set value or ±0.01 x In
10...40 x In: ±5.0% of set value
Voltage:
±2.5% of measured value or ±0.01 x Un
Phase angle: ±2°
Injected currents > 2.0 x start current:
internal time < 42 ms
total time < 50 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
3U>>
BS1
BS2
START
GROUP
TRIP
RESET
REX 521
81