GE 750 User Manual

12-
16
750/760 Feeder Management Relay GE Power Management
12.3 NEUTRAL OVERCURRENT 12 S5 PROTECTION
12
12.3 NEUTRAL OVERCURRENT 12.3.1 DESCRIPTION
Four neutral overcurrent protection elements are provided. Two time overcurrent elements and two instanta-
neous overcurrent elements. They all monitor the calculated neutral current (3
I
o
= I
a
+ I
b
+ I
c
) which has DC off-
set and harmonic components removed. Neutral overcurrent elements can be controlled by the neutral
directional element allowing operation for faults in the permitted direction only. Also, the elements can be
blocked individually or as a group by logic inputs.
12.3.2 NEUTRAL TIME OVERCURRENT
Neutral time overcurrent elements 1 and 2 are programmed in this subgroup. They are two identical protection
elements each equivalent to a single ANSI device 51N neutral time overcurrent relay.
■ NEUTRAL TIME OC 1
■ [ENTER] for more
The Neutral Time Overcurrent 1 setpoints path is:
\ SETPOINTS \ S5 PROTECTION \ NEUTRAL CURRENT \ NEUTRAL TIME OC 1
NEUTRAL TIME OC 1
FUNCTION: Disabled
Range: Disabled, Trip, Trip & AR, Alarm, Latched Alarm, Control
Select the required function.
NEUTRAL TIME OC 1
RELAYS (3-7): -----
Range: Any Combination of the 3-7 AUXILIARY Relays
Select the output relays required.
NEUTRAL TIME OC 1
PICKUP: 1.00 x CT
Range: 0.05 to 20.00 in steps of 0.01 x CT
Select the current level required.
NEUTRAL TIME OC 1
CURVE: Ext Inverse
Range: Ext Inverse, Very Inverse, Norm Inverse, ..., Flex Curve B
See description in Section 12.1: TIME OVERCURRENT CURVE CHARAC-
TERISTICS on page 12–1.
NEUTRAL TIME OC 1
MULTIPLIER: 1.00
Range: 0.00 to 100.00 in steps of 0.01
See description in Section 12.1: TIME OVERCURRENT CURVE CHARAC-
TERISTICS on page 12–1.
NEUTRAL TIME OC 1
RESET: Instantaneous
Range: Instantaneous, Linear
See description in Section 12.1: TIME OVERCURRENT CURVE CHARAC-
TERISTICS on page 12–1.
NEUTRAL TIME OC 1
DIRECTION: Disabled
Range: Disabled, Forward, Reverse
Select the direction(s) of current flow for which operation is permitted.

GE 750 Specifications

General

Brand	GE
Model	750
Category	Relays
Language	English