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S3 PROTECTION
Neutral instantaneous overcurrent protection (50N)
6–64
The relay has two Instantaneous Overcurrent protection elements per setpoint group. The
settings of this function are applied to the calculated neutral current for pickup and trip
flags. The Neutral IOC pickup flag is asserted, when the neutral current is above the PKP
value. The Neutral IOC operate flag is asserted if the element stays picked up for the time
defined by the Neutral IOC Delay setting. If the pickup time delay is set to 0.00 seconds, the
pickup and operate flags will be asserted at the same time. The element drops from pickup
without operation, if the neutral current drops below 97-99% of the pickup value before
the time for operation is reached.
The following path is available using the keypad. For instructions on how to use the
keypad, please refer to Chapter 3 - Working with the Keypad.
PATH:
SETPOINTS > PROTECTION > ETPOINT GROUP 1 (2) > NEUTRAL IOC1(2)
NTRL IOC1(2) FUNCTION
Range: Disabled, Latched Alarm, Alarm, Trip
Default: Disabled
For details see
Common
NTRL IOC PKP
Range: 0.05 to 20 x CT in steps of 0.01 x CT
Default: 1.00 x CT
This setting sets the neutral instantaneous overcurrent pickup level.
NTRL IOC DELAY
Range: 0.00 to 300 sec in steps of 0.01 sec
Default: 0.00 sec
This setting sets the neutral instantaneous overcurrent delay.
NTRL IOC DIRECTION
Range: Disabled, Forward, Reverse
Default: Disabled
This setting provides control to the Neutral IOC1(2) function in terms of permitting
operation upon fault conditions in the selected current flow direction, and blocking it
when faults occur in the opposite direction.
A special case is considered when fault direction is undefined. Then "BLK OC DIR UN"
setting in Neutral Directional defines the fault direction.
OUTPUT RELAY X
For details see
Common
BLOCK 1/2/3
For details see
Common
setpoints.
setpoints.
setpoints.
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS
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