Electrical and magnetic measurements in an electrical engineering factory

The paper describes how, by the application of negative feedback amplifiers and high-speed polarized relays, new methods of performing the commoner electrical and magnetic measurements in power engineering have been developed. Examples include the application of amplifier techniques to the measurement of power and voltage, and of high-speed relays to the measurement of speed, frequency and the slip frequency of induction motors. In a Section on industrial magnetic measurements, apparatus is described for routine tests on whole sheets of transformer steel and on toroidal specimens; while a new approach to routine permeability measurements is given. The paper concludes with an example in the field of dielectric measurements¿the rapid measurement of the power-factor of insulation samples.