Question

It is stated that

(i) balanced three-phase circuits can be solved in per unit on a per-phase basis after converting $\mathbf{∆}$-load impedances to equivalent Y impedances.

(ii) Base values can be selected either on a per-phase basis or on a three phase basis.

(a) Both statements are true.

(b) Neither is true.

(c) Only one of the above is true.

Short answer

Answer

Therefore, the correct option is (a) both statements are true.

Step-by-step solution

Check first statement

The per unit analysis is performed on the per phase system converting from three phase system. This is the advantage of per-unit analysis.

It is easy to perform per-unit analysis on $\mathbf{∆}$connection, when it is converted to Y-connection, and then into single phase.

Hence, statement (i) is correct.

Check second statement

The base value will be same, either it is selected from single phase system or from three phase system.

So, statement (ii) is correct.

Hence, the correct option is (a) both statements are true.