GE UR Series Instruction Manual page 267
Line differential relay
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6 ACTUAL VALUES
Inserting equations 2 and 3 into equation 1 and solving for the fault resistance yields:
⋅
⋅
V
–
m Z I
A
A
R
eqn. 4
=
-----------------------------------
F
I
⋅
BF
I
1
+
------- -
AF
I
AF
Assuming the fault components of the currents, I
ance, does not have any imaginary part gives:
⋅
⋅
V
m Z I
–
A
A
Im
-----------------------------------
eqn. 5
I
AF
where: Im() represents the imaginary part of a complex number. Equation 5 solved for the unknown m creates the following
fault location algorithm:
∗
(
⋅
)
Im V
I
A
AF
m
=
--------------------------------------- -
eqn. 6
∗
(
⋅
⋅
)
Im Z I
I
A
AF
where: * denotes the complex conjugate and:
Depending on the fault type, appropriate voltage and current signals are selected from the phase quantities before applying
equations 6 and 7 (the superscripts denote phases, the subscripts denote stations):
•
For AG faults:
V
V
=
A
•
For BG faults:
V
=
V
A
C
•
For CG faults:
V
=
V
,
A
A
•
For AB and ABG faults:
•
For BC and BCG faults:
•
For CA and CAG faults:
where K
is the zero sequence compensation factor (for equations 8a to 8f)
0
•
For ABC faults, all three AB, BC, and CA loops are analyzed and the final result is selected based upon consistency of
the results
The element calculates the distance to the fault (with m in miles or kilometers) and the phases involved in the fault.
SETTING
FAULT REPORT
TRIG:
Off=0
SETTING
FAULT REPORT
SOURCE:
SRC X 50DD OP
I
A
I
B
I
C
3 _0
I
VA
VB
VC
SHOT # FROM
AUTO RECLOSURE
As fault locator algorithm is based on the single-end measurement method, in 3-terminal configuration the
estimation of fault location may not be correct at all 3 terminals especially if fault occurs behind the line's
NOTE
tap respective to the given relay.
GE Power Management
and I
AF
BF
I
I
I
=
–
AF
A
Apre
A
A
⋅
,
I
I
K
I
eqn. 8a
=
+
A
A
A
0
0 A
B
B
⋅
,
I
=
I
+
K
I
eqn. 8b
A
A
A
0
0 A
BC
⋅
I
=
I
+
K
I
eqn. 8c
A
A
0
0 A
A
B
A
V
V
V
I
I
=
–
,
=
–
A
A
A
A
A
B
C
B
V
V
V
,
I
I
=
–
=
–
A
A
A
A
A
C
A
C
V
V
V
,
I
I
=
–
=
–
A
A
A
A
A
0
1 SEC
Figure 6–5: FAULT LOCATOR SCHEME
L90 Line Differential Relay
are in phase, and observing that the fault resistance, as imped-
eqn. 7
B
I
eqn. 8d
A
C
I
eqn. 8e
A
A
I
eqn. 8f
A
AND
RUN
ACTUAL VALUES
FAULT REPORT #
DATE
TIME
FAULT
FAULT TYPE
LOCATOR
FAULT LOCATION
FAULT# RECLOSE SHOT
6.4 RECORDS
827094A1.CDR
6-19
6
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