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350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
S3 PROTECTION
CHAPTER 6: SETPOINTS
Neutral overvoltage (59N)
The relay has one Neutral Overvoltage element per protection group. This element requires
the three phase Bus VTs to be Wye connected. When setting the pickup for this element, it
is important to consider the error in the VT ratio, as well as the normal voltage unbalance
on the system.
NOTE
NOTE:
This element should be used with caution. It would normally be applied to give line to
ground fault coverage on high impedance grounded or ungrounded systems, which are
isolated. This constraint stems from the fact that a measurement of 3V0 cannot
discriminate between a faulted circuit and an adjacent healthy circuit. Use of a time
delayed back-up or an alarm mode allow other protections an opportunity to isolate the
faulted element first.
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 > S3 PROTECTION > SETPOINT GROUP 1(2) > NEUTRAL OV
NEUTRAL OV FUNCTION
Range: Disabled, Alarm, Latched Alarm,Trip
Default: Disabled
For details see
NEUTRAL OV PKP
Range: 0.00 to 1.25 x VT in steps of 0.01
Default: 0.30 x VT
This setting defines the neutral OV pickup level.
NEUTRAL OV DELAY
Range: 0.00 to 600.00 sec in steps of 0.01 sec
Default: 2.0 s
This setting specifies the time delay before OV operation.
OUTPUT RELAY X
For details see
BLOCK 1/2/3
For details see