Question

Hopkinson’s test gives _______________

(a) Combined iron losses of two machines which can be separated

(b) Combined iron losses of two machines which can’t be separated

(c) Doesn’t include iron losses

(d) Depends on actual setup

I got this question in semester exam.

My question is based upon Hopkinson’s Test topic in division Efficiency and Testing of DC Machines

Answer 1

Correct choice is (b) Combined iron losses of two machines which can’t be separated

Easiest explanation: From Hopkinson’s test both machines are not loaded equally and this crucial in small machines. Thus, it is important to know the separate iron losses for given machines. But, test gives combined losses which are different for different machines as excitation differs.