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CHAPTER 4: SETPOINTS
PROTECTION
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
4–119
Figure 4-39: Percent Differential logic diagram
SETPOINT
Phase
A
current
(I
a)
SETPOINT
FUNCTION
Disabled
T
rip
Pickup
AND
Phase B current
(I
b)
Phase C current
(I
c)
RUN
TRIP
LED
:
PICKUP
OR
Neutral side currents
(I
ns
)
(K
1
-CT
)
Bank
SETPOINT
BLOCK
Of
f
=
0
OR
AND
Configurable
SETPOINTS
Output Relays
Do Not Operate
,
Operate
LED
:
TRIP
Percent Dif
f PKP
C
FlexLogic Operands
Phase
A
current
(I
a
)
Phase B current
(I
b
)
Phase C current
(I
c)
T
erminal side currents
(I
ts
)
(J
1
-CT
)
Bank
I
ar
I
br
I
cr
Restraint
Phasors
I
ad
I
bd
I
cd
Dif
ferential
Phasors
Break
2
Slope
2
Slope
1
Break
1
Percent Dif
f PKP
A
FlexLogic Operands
Percent Dif
f PKP
FlexLogic Operands
Percent Dif
f PKP
B
FlexLogic Operands
Percent Dif
f OP
C
FlexLogic Operands
Percent Dif
f OP
A
FlexLogic Operands
Percent Dif
f OP
FlexLogic Operands
Percent Dif
f OP
B
FlexLogic Operands
Percent Dif
f Sat C
FlexLogic Operands
Percent Dif
f Dir C
OR
AND
Percent Dif
f Sat B
FlexLogic Operands
Percent Dif
f Dir B
OR
AND
Percent Dif
f Sat
A
FlexLogic Operands
Percent Dif
f 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 Dif
f W
arn
FlexLogic Operands
10
s
0s
RUN
RUN
T
pkp
0
T
pkp
0
T
pkp
0
SETPOINT
SETPOINT
SETPOINT
894147.
CDR