GE 750, Instruction Manual

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750/760 Feeder Management Relay GE Power Management
12.7 VOLTAGE 12 S5 PROTECTION
12
12.7.4 LINE UNDERVOLTAGE
Line undervoltage 3 and 4 are identical protection elements that generate outputs in response to an undervolt-
age condition on the line voltage input. The time delay characteristic can be programmed as either definite time
or inverse time. A minimum operating voltage level is programmable to prevent undesired operation before
voltage becomes available. The setpoints for the Undervoltage 3 element are shown below. Undervoltage 4
setpoints are identical.
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LINE UNDERVOLT 3
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[ENTER] for more
The Line Undervoltage 3 setpoints path is:
\ SETPOINTS \ S5 PROTECTION \ VOLTAGE \ LINE UNDERVOLTAGE 3
LINE UNDERVOLTAGE 3
FUNCTION: Disabled
Range: Disabled, Trip, Alarm, Latched Alarm, Control
Select the required function.
LINE UNDERVOLTAGE 3
RELAYS (3-7): -----
Range: Any Combination of the 3-7 AUXILIARY Relays
Select the output relays required.
LINE UNDERVOLTAGE 3
PICKUP: 0.75 x VT
Range: 0.00 to 1.25 in steps of 0.01 x VT
Selects the pickup as a fraction of the nominal bus VT Secondary Voltage. For
example, if the nominal VT secondary voltage is 120 V, and an alarm is
required whenever the voltage goes below 110 V, enter 110 / 120 =
0.92 x VT
for the pickup.
LINE UNDERVOLTAGE 3
CURVE: Definite Time
Range: Definite Time, Inverse Time
Selects the shape of the undervoltage time curve to be used.
Definite Time: Time delay equal to the Bus Undervoltage 1 Delay setpoint.
Inverse Time: See Section 12.1.4: IAC CURVES on page 12–4.
LINE UNDERVOLTAGE 3
DELAY: 2.0 s
Range: 0.0 to 6000.0 in steps of 0.1 s
Selects the minimum operating time of Line Undervoltage 3. If voltage is above
the pickup level or below the minimum operating voltage the timer resets.
MINIMUM OPERATING
VOLTAGE: 0.30 x VT
Range: 0.00 to 1.25 in steps of 0.01 x VT
The Line Undervoltage 3 element is inhibited for voltages below this level. Set-
ting this voltage to
0.00 will allow a dead bus to be considered a fault condition.