CHAPTER 6: SETPOINTS
S2 SYSTEM SETUP
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
6–25
S2 System Setup
Figure 6-11: Main system setup menu
Current sensing
PATH
:
SETPOINTS > S2 SYSTEM SETUP > CURRENT SENSING
PHASE CT PRIMARY
Range: 1 A to 6000 A
Default: 500 A
Enter the primary rating of the three-phase feeder CTs wired to the relay phase CT
terminals (see above). For correct operation, the relay CT tap must match the feeder CT
tap (5 A or 1 A).
As the phase CTs are connected in wye (star), the calculated phasor sum of the three
phase currents (Ia + Ib + Ic = Neutral Current = 3I
0
) is used as the input for the neutral
overcurrent. In addition, a zero-sequence (core balance) CT which senses current in all of
the circuit primary conductors, or a CT in a neutral grounding conductor may also be
used.
PHASE CT SECONDARY
Range: 1 A or 5 A
Default: 5 A
Configurable 1 A or 5 A secondary, available with Phase Current option ‘P0’ installed.
Enter the rated phase CT secondary current of the three-phase current transformers.
GROUND [SENS GND] CT PRIMARY
Range: [1 A to 600 A] 1 A to 6000 A
Default: 50 A
For the above configuration, the ground CT primary rating must be entered. To detect
low level ground fault currents, the sensitive ground input may be used. In this case, the
sensitive ground CT primary rating must be entered. The Sens GND CT primary range is
1 A to 600 A
The relay phase and ground CT types (5 A, 1 A) must match the feeder phase and ground
CT taps.
GROUND [SENS GND] CT TYPE
Range: 1 A or 5 A
Default: 5 A
Configurable 1 A or 5 A secondary, available with Ground Current option ‘G0’ or ‘S0’
installed. Enter the rated ground CT secondary current of the ground current
transformer.
S2 SYSTEM SETUP
CURRENT SENSING
VOLTAGE SENSING
POWER SYSTEM
BREAKER
USER CURVE
FLEXCURVE A
FLEXCURVE B
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898765A3.cdr
