Underfrequency Restoration - GE Feeder Management Relay 750 Instruction Manual

5.8 S7 CONTROL
PATH: SETPOINTS S7 CONTROL
UNDERFREQ RESTORE
[ENTER] for more
This scheme is initiated by a trip of either the Bus Underfrequency elements. After the feeder breaker has been tripped, it
will display the
UFreq Restore Init
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
5
previous initiation is only effective if the voltage and frequency are above the restoration thresholds. A "Block Restoration"
logic input is available to prevent both initiation and operation. It is recommended that if automatic underfrequency restora-
tion is to be used, that the cold load pickup feature is also enabled, to prevent the breaker from tripping shortly after it is
automatically closed.
5-106
Courtesy of NationalSwitchgear.com
UNDERFREQ RESTORE
ð
UNDERFREQ RESTORE
ENTER
ESCAPE FUNCTION: Disabled
UNDERFREQ RESTORE
ESCAPE
MESSAGE RELAYS (3-7): -----
UNDERFREQ RESTORE
ESCAPE
MIN VOLTS: 0.90 x VT
MESSAGE
UNDERFREQ RESTORE
ESCAPE
MIN FREQ: 59.90 Hz
MESSAGE
UNDERFREQ RESTORE
ESCAPE
DELAY: 10 s
MESSAGE
INCOMPLETE SEQUENCE
ESCAPE
TIME: 100 min
MESSAGE
and operate any programmed output relays. Once initiated it will monitor the bus voltage
750/760 Feeder Management Relay

5.8.6 UNDERFREQUENCY RESTORATION

Range: Disabled, Alarm, Latched Alarm, Control
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
5 SETPOINTS
GE Multilin