GE 750 Instruction Manual page 260

S7 CONTROL
5.8.6 Underfrequency Restore
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UNDERFREQUENCY
RESTORATION
5 - 134
FIGURE 5–64: Undervoltage Restoration Logic
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PATH: SETPOINTS S7 CONTROL
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MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
This scheme is initiated by a trip of either the Bus Underfrequency elements. After the
feeder breaker has been tripped, it will display the
programmed output relays. Once initiated it will monitor the bus voltage level and
frequency, and send a close command to the Close Relay when the voltage on the phase A
input has risen above the programmed minimum level and frequency for a selected time
interval. The scheme is equipped with an incomplete sequence timer, so it will not remain
initiated for an indeterminate time, but will automatically reset if the voltage does not
recover during the programmed interval. Initiation of the scheme can be canceled by a
reset command. Cancellation of a previous initiation is only effective if the voltage and
frequency are above the restoration thresholds. A "Block Restoration" logic input is
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UNDERFREQUENCY RESTORATION
UNDERFREQ RESTORE
FUNCTION: Disabled
UNDERFREQ RESTORE
RELAYS (3-7): -----
UNDERFREQ RESTORE
MIN VOLTS: 0.90 x VT
UNDERFREQ RESTORE
MIN FREQ: 59.90 Hz
UNDERFREQ RESTORE
DELAY: 10 s
INCOMPLETE SEQUENCE
TIME: 100 min
UFreq Restore Init
750 FEEDER MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS
Range: Disabled, Alarm,
Latched Alarm,
Range: Any combination of 3
to 7 Auxiliary relays
Range: 0.00 to 1.25 x VT in
steps of 0.01
Range: 20.00 to 65.00 Hz in
steps of 0.01
Range: 0 to 10000 s in steps
of 1
Range: 1 to 10000 min. in
steps of 1
and operate any