GE 750 Instruction Manual page 143

S5 Protection
GE Multilin
FIGURE 5–13: Neutral Directional Voltage Polarization
The Neutral Directional specific setpoints are described below.
• NEUTRAL POLARIZING: 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: Enter the maximum torque angle by which the
operating current leads the polarizing voltage. This is the angle of maximum
sensitivity. This setpoint affects voltage polarizing only. Additional information is
provided in the figure above.
• MIN POLARIZING VOLTAGE: This setpoint 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 × VT" is appropriate
for most solidly grounded systems.
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Feeder Management Relay
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