ABB RELION REX640 Technical Manual page 601

1MRS759142 C
REX640
Technical Manual
The vector group matching can be implemented either on both, winding 1 and winding
2, or only on winding 1 or winding 2, at intervals of 30° with the Clock number setting.
When the vector group matching is Yy0 and the CT connection type is according to
"Type 2", the phase angle of the phase currents connected to the protection relay does
not change. When the vector group matching is Yy6, the phase currents are turned
180° in the protection relay.
Example 1
Vector group matching of a Ynd11-connected power transformer on winding 1, CT
connection type according to type 1. The Winding 1 type setting is "YN", Winding 2
type is "d" and Clock number is "Clk Num 11". This is compensated internally by
giving winding 1 internal compensation value +30° and winding 2 internal
compensation value 0°:
I I
−
L L
I 1 2
=
L mHV
1
3
I I
−
I L 2 L 3
=
L mHV 2
3
I I
−
I L 3 L 1
=
L mHV 3
3
GUID-4BEE3D94-6BFE-4831-ADF2-8B2FA872434F V1 EN
Example 2
But if vector group is Yd11 and CT connection type is according to type 1, the
compensation is a little different. The Winding 1 type setting is "Y", Winding 2 type is
"d" and Clock number is "Clk Num 11". This is compensated internally by giving
winding 1 internal compensation value 0° and winding 2 internal compensation value
-30°;
I I
L − L
1 3
I
=
L mLV 1
3
I I
L 2 − L 1
I
L mLV 2 =
3
I I
L 3 − L 2
I
L mLV 3 =
3
GUID-F8BA2E45-443D-408A-ACB3-AC8108256B78 V1 EN
The "Y" side currents stay untouched, while the "d" side currents are compensated to
match the currents actually flowing in the windings.
In this example there is no neutral current on either side of the transformer (assuming
there are no earthing transformers installed). In the previous example, however, the
matching is done differently to have the winding 1 neutral current compensated at the
same time.
Section 4
Protection functions
(Equation 106)
(Equation 107)
595