GE 845 - Page 311

CHAPTER 4: SETPOINTS PROTECTION
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–183
Figure 4-62: Ground Instantaneous Overcurrent Protection logic diagram
SETPOINTS
Ground current (Ig)
RUN
SETPOINTS
BLOCK: Off = 0
PICKUP:
Ig > PICKUP
OR
AND
Aux Relay # upon selection
LED: TRIP
OR
OR
From Cold Load Pickup
From Ground CT
AND AND
SETPOINT
FUNCTION: Disabled = 0 Trip Alarm
Latched Alarm
PICKUP DELAY:
SETPOINTS
t
PKP
From Autoreclose
(per shot settings)
LED: ALARM
RESET
Command
AND
S R
LATCH
LED: PICKUP
SETPOINTS
Do Not Operate, Operate RELAYS
DIRECTION:
DROPOUT DELAY:
t
RST
Configurable
Ground IOC 1 PKP
FLEXLOGIC OPERANDS
Ground IOC 1 OP
FLEXLOGIC OPERANDS
Set
Dominant
Direction (from Ground
Directional OC element)
From Manual Close
Blocking
894119A1.cdr
850 Only
850, 889, 845 Only