GE Multilin 350 Series

CHAPTER 6: SETPOINTS S3 PROTECTION
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–107
Figure 36: Underfrequency logic diagram
Phase Voltage Inputs
(associated setpoints)
SETPOINTS
Vab
SETPOINT
UNDERFREQ FUNCTN: Disabled = 0
Latched Alarm
UNDERFREQ PKP:
Vbc Vca
Operate Output Relay 1 (TRIP)
Event Recorder
Transient Recorder
LED: TRIP
Alarm
OR
OR
AND
SETPOINTS
Operate
output relays
upon
selection
OUTPUT RELAY 4 OUTPUT RELAY 5 OUTPUT RELAY 6 OUTPUT RELAY 3
Trip
AND
Trip
(To Breaker Failure)
SETPOINTS
BLOCK 1: Off=0 BLOCK 2: Off=0 BLOCK 3: Off=0
OR
RUN
Van Vbn
Vcn
None
AND
Delta
Wye
LED: PICKUP
Event Recorder
Transient Recorder
Underfrequency1(2)
Message
f < PICKUP
Frequency
Measurement
f ( Va) - frequency
Va > Minimum
MIN VOLTAGE:
SETPOINT
f=0
UNDERFREQ
DELAY:
SETPOINT
t
PKP
LED: ALARM
RESET
Command
AND
S
R
LATCH
898004.cdr
Courtesy of NationalSwitchgear.com