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CHAPTER 6: SETPOINTS
Negative sequence instantaneous overcurrent (50_2)
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
The 350 relay has one Negative Sequence Overcurrent element per protection group. The
negative sequence over-current protection responds to negative sequence current, where
it is calculated as .
The negative sequence over-current elements are uniquely suited to detect phase-phase
faults and are not sensitive to balanced loads. While negative sequence elements do not
respond to balanced load, they do detect the negative sequence current present in
unbalanced load. For this reason, select an element pickup setting above the maximum
expected current due to load unbalance.
PATH:
SETPOINTS > S3 PROTECTION > SETPOINT GROUP 1(2) > NEG SEQ IOC
NEG SEQ IOC FUNCTION
Range: Disabled, Latched Alarm, Alarm, Trip
Default: Disabled
For details see
Common
NEG SEQ IOC PKP
Range: 0.05 to 20.00 x CT in steps of 0.01 x CT
Default: 1.00 x CT
This setting defines the negative sequence IOC pickup level.
NEG SEQ IOC DELAY
Range: 0.00 to 300.00 sec in steps of 0.01 sec
Default: 0.00 sec
This setting specifies the time delay before IOC operation. .
OUTPUT RELAY X
For details see
Common
BLOCK 1/2/3
For details see
Common
setpoints.
setpoints.
setpoints.
S3 PROTECTION
6–71
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