Routine testing equipment for transformer steels

The paper describes the application of an a.c./d.c. null wattmeter method of iron testing to routine work. The wattmeter circuit is incorporated with computing networks so arranged that the work of the operator is confined to the insertion of basic data and the establishment of a series of four null balances. Use is made of an a.c. peak fluxmeter in establishing the conditionsof test, and compensation is made automatically for circuit losses and air-flux corrections. The method of setting up and of calibration is briefly described.