GE 750 Instruction Manual page 166

750/760
Feeder Management Relay
UNDERFREQ 1
5–70
b) Underfrequency
PATH: SETPOINTS S5 PROTECTION
[ ] UNDEFREQUENCY 1
FUNCTION: Disabled
UNDEFREQUENCY 1
MESSAGE
RELAYS (3-7): -----
UNDEFREQUENCY 1
MESSAGE
PICKUP: 59.00 Hz
UNDEFREQUENCY 1
MESSAGE
DELAY:
MINIMUM OPERATING
MESSAGE
VOLTAGE: 0.70 x VT
MINIMUM OPERATING
MESSAGE
CURRENT: 0.20 x CT
There are two identical underfrequency protection elements, ANSI devices 81U-1
and 81U-2. The setpoints for the Underfrequency 1 element are shown above; the
Underfrequency 2 setpoints are identical. See Overview on page 5–32 for additional
setting details.
• MINIMUM OPERATING VOLTAGE: Enter the minimum voltage required for
underfrequency element operation. This setpoint prevents incorrect operation
before energization of the source to the relay location, and during voltage dips.
• MINIMUM OPERATING CURRENT: Enter the minimum value of current
required on any phase to allow the underfrequency element to operate. This
setpoint is used to prevent underfrequency tripping during periods of light load,
when this action would have an insignificant effect on the system.
FIGURE 5–32: Underfrequency Logic
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FREQUENCY UNDERFREQ 1(2)
Range: Disabled, Trip, Alarm, Latched
Alarm, Control
Range: Any combination of 3 to 7
Auxiliary relays.
Range: 20.00 to 65.00 Hz in steps of
0.01
Range: 0.00 to 600.00 s in steps of 0.1
2.00 s
Range: 0.00 to 1.25 x VT in steps of
0.01
Range: 0.00 to 1.25 x CT in steps of
0.01
S5 Protection
GE Multilin