Exam Question

(a) With the aid of delta and star connection diagrams, state the basic equation from which the delta-star and star-delta connection equation can be derived (6)

(b) A 230/115V, single phase transformer is supplied with a load of 5A at p.f. of 0.86 lagging, the no-load current is 0.2 A at p.f 0.208 lagging. Calculate the primary current and p.f (10)