ABB 615 Series ANSI, Техническое руководство

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Section 4
1MAC050144-MB C
Protection functions
340 615 series ANSI
Technical Manual
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°;
(Equation 37)
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°;
(Equation 38)
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 grounding 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 4”, “Clk Num 6”, “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 ground faults occurring outside the protection area is eliminated in the
numerically implemented delta connection before the differential current and the
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