1MAC308145-MB E Section 3
RER620 application
RER620 33
Application Manual
Figure 12: Instantaneous phase overcurrent protection
The ground-fault function 51N/50N is used as non-directional ground-fault protection for
feeders. The function picks up and trips when the measured (IG) or calculated (IN) ground
current exceeds the set limit. The trip time characteristic for low stage 51N and high stage
50N-1/2 can be selected to be either definite time (DT) or inverse definite minimum time
(IDMT). The instantaneous stage 50N/G-3 always trips with the DT characteristic.
The negative phase-sequence current protection 46 can be used for high sensitivity to
unbalance situations such as single phase, phase-to-phase fault, etc. The phase
discontinuity protection (46PD) provides protection for interruptions in the normal
three-phase load supply like in downed conductor situations.
The sensitive earth-fault protection (50SEF) and high impedance fault detection (HIZ)
provide protection against high impedance faults. If the load unbalance is high, 50SEF
needs to be set high to avoid misoperations which render 50SEF ineffective for such
applications. In those cases, HIZ can provide detection which would otherwise be
undetected.
SPHIPTOC1(50P-3
BLOCK
ENA_MULT
TRIP
PICKUP
TRIP_A
TRIP_B
TRIP_C
PICKUP_A
PICKUP_B
PICKUP_C
NOT
IN OUT
AND
B1
B2
O
AND
B1
B2
O
AND
B1
B2
O
AND
B1
B2
O
AND
B1
B2
O
AND
B1
B2
O
AND
B1
B2
O
SPHIPTOC1_50P-3_OPERATE
SPCGGIO1_O7_SWITCH_MODE
SPHIPTOC1_50P-3_OPERATE_B
SPHIPTOC1_50P-3_OPERATE_A
SPHIPTOC1_50P-3_OPERATE_C
SPHIPTOC1_50P-3_START_A
SPHIPTOC1_50P-3_START_B
SPHIPTOC1_50P-3_START_C
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