GE 889 - Page 249

CHAPTER 4: SETPOINTS PROTECTION
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–119
Figure 4-39: Percent Differential logic diagram
SETPOINT
Phase A current (Ia)
SETPOINT
FUNCTION
Disabled
Trip
Pickup
AND
Phase B current (Ib) Phase C current (Ic)
RUN
TRIP
LED: PICKUP
OR
Neutral side currents (I
ns
)
(K1-CT) Bank
SETPOINT
BLOCK Off = 0
OR
AND
Configurable
SETPOINTS
Output Relays Do Not Operate, Operate
LED: TRIP
Percent Diff PKP C
FlexLogic Operands
Phase A current (Ia) Phase B current (Ib) Phase C current (Ic)
Terminal side currents (
I
ts
)
(J1-CT) Bank
I
ar
I
br
I
cr
Restraint Phasors
I
ad
I
bd
I
cd
Differential
Phasors
Break2 Slope2 Slope1 Break1
Percent Diff PKP A
FlexLogic Operands
Percent Diff PKP
FlexLogic Operands
Percent Diff PKP B
FlexLogic Operands
Percent Diff OP C
FlexLogic Operands
Percent Diff OP A
FlexLogic Operands
Percent Diff OP
FlexLogic Operands
Percent Diff OP B
FlexLogic Operands
Percent Diff Sat C
FlexLogic Operands
Percent Diff Dir C
OR
AND
Percent Diff Sat B
FlexLogic Operands
Percent Diff Dir B
OR
AND
Percent Diff Sat A
FlexLogic Operands
Percent Diff Dir A
OR
AND
OR
|I
d
|=|I
ts
-I
ns
|
|I
r
| = MAX{|I
ts
|, |I
ns
|}
I
ad
>( 0 . 5 x PKP)
I
bd
>( 0 . 5 x PKP)
I
cd
> ( 0. 5 x PKP )
OR
Percent Diff Warn
FlexLogic Operands
10s
0s
RUN RUN
T
pkp
0
T
pkp
0
T
pkp
0
SETPOINT
SETPOINT SETPOINT
894147.CDR