Hawkins Electrical Guide v. 08 (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

Ans. Mineral oil.

Fig. 2,855.—General arrangement of air blast transformers and blowers.

Ques. How is it obtained?

Ans. By fractional distillations of petroleum unmixed with any other substances and without subsequent chemical treatment.

Ques. What is the important requirement for transformer oil?

Ans. It should be free from moisture, acid, alkali or sulphur compounds.

Ques. How may the presence of moisture be determined?

Ans. By thrusting a red hot iron rod in the oil; if it "crackle," moisture is present.