ABB REX 521 - Page 20

20
1MRS751802-MUM
Protection Relay
Technical Reference Manual, Standard Configurations
REX 521
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
3Ithdev Three-phase thermal overload protection for devices
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
U1<U1U2> Phase sequence voltage protection
f1 Underfrequency or overfrequency protection, stage 1
f2 Underfrequency or overfrequency protection, stage 2
FUSEF Fuse failure protection
SYNC1 Synchro-check / voltage-check function
Table 2.-3 Control functions available in the different standard configurations
of REX 521
Function Description
I<->O CB1 Circuit breaker control with indication
I<->O IND1 Object indication
I<->O IND2 Object indication
I<->O IND3 Object indication
I<->O POS Logic control position selector
ALARM1-8 Alarm LED 1-8
Table 2.-4 Measurement functions available in the different standard
configurations of 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
3U_B Three-phase voltage measurement
f System frequency measurement
PQE Three-phase power and energy measurement
MEAI1 Analog measuring function
Table 2.-2 Protection functions available in the different standard
configurations of REX 521
Function Description