ABB REX 521 Technical Reference Manual, Standard Configurations page 15

1MRS 751802-MUM Protection Relay
Technical Reference Manual, Standard Configurations
Table 2.-2 Protection functions available in the different standard
configurations of the REX 521
Function Description
3I> Three-phase non-directional overcurrent protection, low-set stage
3I>> Three-phase non-directional overcurrent protection, high-set stage
3I>>> Three-phase non-directional overcurrent protection, instantaneous stage
Io> Non-directional earth-fault protection, low-set stage
Io>> Non-directional earth-fault protection, high-set stage
Io>>> Non-directional earth-fault protection, instantaneous stage
Io>-> Directional earth-fault protection, low-set stage
Io>>-> Directional earth-fault protection, high-set stage
Io>>>-> Directional earth-fault protection, instantaneous stage
3I>-> Three-phase directional overcurrent protection, low-set stage
3I>>-> Three-phase directional overcurrent protection, high-set stage
3U> Three-phase overvoltage protection, low-set stage
3U>> Three-phase overvoltage protection, high-set stage
3U< Three-phase undervoltage protection, low-set stage
3U<< Three-phase undervoltage protection, high-set stage
3I2f> Three-phase transformer inrush and motor start-up current detector
Iub> Phase discontinuity protection
3Ith> Three-phase thermal protection for cables
O->I Auto-reclose function (5 shots)
Uo> Residual overvoltage protection, low-set stage
Uo>> Residual overvoltage protection, high-set stage
Uo>>> Residual overvoltage protection, instantaneous stage
f1 Underfrequency or overfrequency protection, stage 1
f2 Underfrequency or overfrequency protection, stage 2
SYNC Synchro-check / voltage-check function
Table 2.-3 Control functions available in the different standard configurations
of the REX 521
Function Description
I<->O CB1 Circuit breaker control with indication
I<->O IND1 Object indication
I<->O IND2 Object indication
I<->O POS Logic control position selector
Table 2.-4 Measurement functions available in the different standard
configurations of the REX 521
Function Description
3I Three-phase current measurement
Io Neutral current measurement
Uo Residual voltage measurement
DREC Transient disturbance recorder
3U Three-phase voltage measurement
REX 521
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