Which of the following statements is true?

Question

Question

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BPSC AE Paper 6 (Electrical) 25 Mar 2022 Official Paper

The zero sequence reactance of a transformer is approximately equal to the negative sequence reactance.
The zero sequence reactance of a transformer is approximately equal to the positive sequence reactance.
The zero sequence reactance is larger than the negative sequence reactance, but less than the positive sequence reactance in the transformer.
The zero sequence reactance depends upon the connection and winding of the transformer.

Answer 1

Zero sequence impedance of the transformer:

Zero sequence impedance is the impedance offered by the system to the flow of zero sequence current.
The zero sequence reactance of transformers depends upon the connection and winding of the transformer.
Since the transformer is a static device, the zero, positive and negative reactances are equal in magnitude.

Zero sequence network of the transformer:

F5 Madhuri Engineering 26.05.2022 D5

Switch 1 will be operated when the primary side of the transformer will be connected in a star with a neutral.
Switch 2 will be operated when the secondary side of the transformer will be connected in a star with a neutral.
Switch 3 will be operated when the primary side of the transformer will be delta connected.
Switch 4 will be operated when the secondary side of the transformer will be delta connected.