644
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
PHASE DISTANCE APPLIED TO POWER TRANSFORMERS
CHAPTER 15: THEORY OF OPERATION
Table 25: Phase distance input signals for wye-delta transformers
Dy5
AB
BC
CA
Dy7
AB
BC
CA
Dy9
AB
BC
CA
Dy11
AB
BC
CA
Transformer
connection
Loop
Current transformation
Voltage transformation
Yd1
AB
BC
CA
Yd3
AB
BC
CA
Transformer
connection
Loop
Current transformation
Voltage transformation
B
AB
I
I
3
_21P
-
=
(
)
AB
BC
AB
V
V
V
-
=
3
1
_21P
C
BC
I
I
3
_21P
-
=
(
)
BC
CA
BC
V
V
V
-
=
3
1
_21P
A
CA
I
I
3
_21P
-
=
(
)
CA
AB
CA
V
V
V
-
=
3
1
_21P
A
AB
I
I
3
_21P
-
=
(
)
AB
CA
AB
V
V
V
-
=
3
1
_21P
B
BC
I
I
3
_21P
-
=
(
)
BC
AB
BC
V
V
V
-
=
3
1
_21P
C
CA
I
I
3
_21P
-
=
(
)
CA
BC
CA
V
V
V
-
=
3
1
_21P
C
AB
I
I
3
_21P
-
=
(
)
BC
CA
AB
V
V
V
-
=
3
1
_21P
A
BC
I
I
3
_21P
-
=
(
)
CA
AB
BC
V
V
V
-
=
3
1
_21P
B
CA
I
I
3
_21P
-
=
(
)
AB
BC
CA
V
V
V
-
=
3
1
_21P
B
AB
I
I
3
_21P
-
=
(
)
BC
AB
AB
V
V
V
-
=
3
1
_21P
C
BC
I
I
3
_21P
-
=
(
)
CA
BC
BC
V
V
V
-
=
3
1
_21P
A
CA
I
I
3
_21P
-
=
(
)
AB
CA
CA
V
V
V
-
=
3
1
_21P
(
)
C
B
A
AB
I
I
I
I
-
-
=
2
3
1
_21P
A
AB
V
V
3
_21P
=
(
)
C
A
B
BC
I
I
I
I
-
-
=
2
3
1
_21P
B
BC
V
V
3
_21P
=
(
)
B
A
C
CA
I
I
I
I
-
-
=
2
3
1
_21P
C
CA
V
V
3
_21P
=
(
)
C
B
A
AB
I
I
I
I
2
3
1
_21P
-
+
=
C
AB
V
V
3
_21P
-
=
(
)
A
C
B
BC
I
I
I
I
2
3
1
_21P
-
+
=
A
BC
V
V
3
_21P
-
=
(
)
B
C
A
CA
I
I
I
I
2
3
1
_21P
-
+
=
B
CA
V
V
3
_21P
-
=