GE 750 - Page 173

GE Power Management 750/760 Feeder Management Relay 12-
21
12 S5 PROTECTION 12.3 NEUTRAL OVERCURRENT
12
The setpoints for Neutral Directional are as follows:
■ NEUTRAL DIRECTION
■ [ENTER] for more
The Neutral Time Overcurrent 1 setpoints path is:
\ SETPOINTS \ S5 PROTECTION \ NEUTRAL CURRENT \ NEUTRAL DIRECTION
NEUTRAL DIRECTIONAL
FUNCTION: Disabled
Range: Disabled, Alarm, Latched Alarm, Control
Select the required function.
NEUTRAL DIRECTIONAL
RELAYS (3-7): -----
Range: Any Combination of the 3-7 AUXILIARY Relays
Select the output relays required.
NEUTRAL POLARIZING:
Voltage
Range: Voltage, Current, Dual
If neutral directional control with both voltage and current polarized elements is
desired, enter
Dual . If neutral directional control with only the voltage polarized
element is desired, enter
Voltage . If neutral directional control with only the
current polarized element is desired, enter
Current .
NEUTRAL DIRECTIONAL
MTA: 315° Lead
Range: 0 to 359 Lead in steps of 1
°
Enter the maximum torque angle by which the operating current leads the
polarizing voltage. This is the angle of maximum sensitivity. This setting affects
voltage polarizing only. See Figure 12–9: NEUTRAL DIRECT VOLTAGE
POLARIZING on page 12–20 for more information.
MINIMUM POLARIZING
VOLTAGE: 0.05 x VT
Range: 0.00 to 1.25 in steps of 0.01 x VT
This setting affects the voltage element only. As the system zero sequence
voltage is used as the polarizing voltage for this element, a minimum level of
voltage must be selected to prevent operation caused by system unbalanced
voltages or VT ratio errors. For well-balanced systems and 1% accuracy VTs,
this setpoint can be as low as 2% of VT nominal voltage. For systems with
high-resistance grounding or floating neutrals, this setpoint can be as high as
20%. The default value of
0.05 x VT is appropriate for most solidly grounded
systems.