GE MI-869 - Page 283

CHAPTER 4: SETPOINTS PROTECTION
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–165
Figure 4-54: Underpower logic diagram
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Three Phase Currents
from CT bank
IA IB IC
WYE DELTA VAG VAB VBG VBC VCG VCA
Three Phase Voltages from
VT Bank
VOLTAGE CONNECTION
SETPOINT
Configurable TRIP FUNCTION:
Disabled=0
Trip
Motor Stopped
FLEXLOGIC OPERAND
P
3p h
= P
a
+ P
b
+ P
c
IA mag > 0.1 x FLA IB mag > 0.1 x FLA IC mag > 0.1 x FLA
AND
VA mag > 0.25 x Vrated VB mag > 0.25 x Vrated VC mag > 0.25 x Vrated
AND
SETPOINT
BLOCK: Off=0
AND
START BLOCK DELAY:
SETPOINT
t
BLK
0
AND
SETPOINT
LATCH ALARM ALARM FUNCTION:
Disabled=0
ALARM
OR
AND
AND
RUN
TRIP PICKUP:
SETPOINT
P
3p h
< Trip Pickup
RUN
ALARM PICKUP:
SETPOINT
P
3p h
< ALarm Pickup
TRIP PICKUP DELAY:
SETPOINTS
TRIP DROPOUT DELAY: t
PKP
t
DPO
ALARM PICKUP DELAY:
SETPOINTS
ALARM DROPOUT DELAY:
t
PKP
t
DPO
AND
Operate Output
Relay 1(TRIP)
LED: TRIP
LED: Alarm
AND AND
OR
LATCH
S R
RESET
Command
Underpwr Trip PKP
FLEXLOGIC OPERANDS
Underpwr Trip OP
Underpwr Alarm PKP
FLEXLOGIC OPERANDS
Underpwr Alarm OP
SETPOINT
Trip Output Relay X
Do Not Operate, Operate
SETPOINT
Alarm Output Relay X
Do Not Operate, Operate
OR