ABB RED615 Technical Manual page 393

1YHT530004D05 D
615 series
Technical Manual
by giving winding 1 internal compensation value +30° and winding 2 internal
compensation value 0°:
I − I
L 1 L 2
I =
L mHV 1
3
−
I I
2 3
L L
I =
L mHV 2
3
−
I I
L 3 L 1
I =
L mHV 3
3
GUID-633921A4-D973-4BD2-BFDF-E9FF73C3B9E3 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 1 L 3
=
I
1
L mLV
3
−
I I
L 2 L 1
I =
L mLV 2
3
I − I
L 3 L 2
I =
L mLV 3
3
GUID-41089920-D9BF-4574-96FB-0B1F48019391 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.
Zero-sequence component elimination
If Clock number is "Clk Num 2", "Clk Num 4", "Clk Num 8" or "Clk Num 10", the
vector group matching is always done on both, winding 1 and winding 2. The
combination results in the correct compensation. In this case the zero-sequence
component is always removed from both sides automatically. The Zro A
elimination parameter cannot change this.
If Clock number is "Clk Num 1", "Clk Num 5", "Clk Num 7" or "Clk Num 11", the
vector group matching is done on one side only. A possible zero-sequence
component of the phase currents at earth faults occurring outside the protection
area is eliminated in the numerically implemented delta connection before the
differential current and the biasing current are calculated. This is why the vector
Section 4
Protection functions
(Equation 46)
(Equation 47)
387