Hawkins Electrical Guide v. 06 (of 10) / Questions, Answers, & Illustrations, A progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications

by N. Hawkins

Ques. Does a transformer take any current when the secondary circuit is open?

Ans. Yes, a "no load" current passes through the primary.

Ques. Why?

Ans. The energy thus supplied balances the core losses.

Fig. 1,945.—Cover construction of Wagner 350 kva., oil filled 1,100-2,200 volt transformer. In transformers with corrugated cases, the base and top ring are cast to the corrugated iron sheets.

Ques. Are the iron or copper losses the more important, and why?

Ans. The iron losses, because these are going on as long as the primary pressure is maintained, and the copper losses take place only while energy is being delivered from the secondary.