CHAPTER 15: THEORY OF OPERATION
PHASE DISTANCE APPLIED TO POWER TRANSFORMERS
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
643
Figure 551: Applications of the phase distance transformer settings
NOTE
NOTE:
In the following tables, the suffix “_21P” indicates current or voltage inputs to the phase
distance (ANSI 21P) element.
Table 24: Phase distance input signals for delta-wye transformers
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Transformer
connection
Loop
Current transformation
Voltage transformation
None
AB
BC
CA
Dy1
AB
BC
CA
Dy3
AB
BC
CA
B
A
AB
I
I
I
-
=
_21P
AB
AB
V
V
=
_21P
B
A
AB
I
I
I
-
=
_21P
BC
BC
V
V
=
_21P
A
C
CA
I
I
I
-
=
_21P
CA
CA
V
V
=
_21P
A
A
I
I
3
_21P
=
(
)
CA
AB
AB
V
V
V
-
=
3
1
_21P
B
B
I
I
3
_21P
=
(
)
AB
BC
BC
V
V
V
-
=
3
1
_21P
C
C
I
I
3
_21P
=
(
)
BC
CA
CA
V
V
V
-
=
3
1
_21P
C
AB
I
I
3
_21P
-
=
(
)
CA
BC
AB
V
V
V
-
=
3
1
_21P
A
BC
I
I
3
_21P
-
=
(
)
AB
CA
BC
V
V
V
-
=
3
1
_21P
B
CA
I
I
3
_21P
-
=
(
)
BC
AB
CA
V
V
V
-
=
3
1
_21P