Δ - Δ Connected Transformer
The schematic diagram of a Δ - Δ connected transformer is shown in Fig. 7.13. Now we have
|
(7.61) |
Again
Fig. 7.13 Schematic diagram of a Δ - Δ connected transformer.
Therefore from (7.61) we get
|
(7.62) |
The sequence components of the line-to-line voltage VAB can be written in terms of the sequence com ponents of the line-to-neutral voltage as
|
(7.63) |
|
(7.64) |
Therefore combining (7.62)-(7.64) we get
|
(7.65) |
Hence we get
|
(7.66) |
Thus the positive and negative sequence equivalent circuits are represented by a series impedance that is equal to the leakage impedance of the transformer. Since the Δ -connected winding does not provide any path for the zero sequence current to flow we have
However the zero sequence current can sometimes circulate within the Δ windings. We can then draw the zero sequence equivalent circuit as shown in Fig. 7.14.
Fig. 7.14 Zero sequence diagram of Δ - Δ connected transformer.
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