GE 850 - Page 408

6–140 850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
FREQUENCY ELEMENTS CHAPTER 6: PROTECTION SETPOINTS
Figure 6-61: Underfrequency Protection logic diagram
892737A4.cdr
LED: PICKUP
CT INPUT
CT Bank 1 – J1
SETPOINTS
BLOCK : Off=0
AND
SETPOINTS
UNDERFREQ 1 FUNCTION : Disabled Trip Alarm Latched Alarm Configurable
OR
Positive -
sequence
SETPOINTS
UNDERFREQ 1 MINIMUM CURRENT : I ≥MINIMUM
SETPOINTS
UNDERFREQ 1 MINIMUM VOLTAGE :
AND
SETPOINTS
UNDERFREQ 1 PICKUP: 0<f≤PICKUP
FREQUENCY f
RUN
SETPOINTS
UNDERFREQ 1 PICKUP DELAY :
t
PKP
t
DPO
UNDERFREQ 1 DROPOUT DELAY :
Underfreq1 OP
FlexLogic Operands
Underfreq 1 PKP
AN D AND AND
Command
RESET
OR
LED: ALARM
LED: TRIP
Operate Output Relay 1 (TRIP)
RUN
V ≥MINIMUM
RUN
SETPOINTS
OUTPUT RELAYS 3(X) Do Not Operate , Operate
S
LATCH
Set-
Dominant
R
SETPOINTS
UNDERFREQ 1 VT INPUT :
Positive -
sequence
Composite
SETPOINTS
Ph VT Bnk 1 – J2
wye/delta
Vx