Revision Standard - Active.Instructions are given for measuring electrical quantities that are commonly needed to determine the performance characteristics of electric machinery and equipment. Methods are given for measuring voltage, current, power, energy, power factor, frequency, impedance, and magnetic quantities, with either analog or digital indicating or integrating instruments, in DC or AC rotating machines, transformers, induction apparatus, arc and resistance heating equipment, mercury arc, thermionic, or solid-state rectifiers and inverters. Ancillary instruments and equipment are discussed. Computer-based techniques and the use of optical fibers in instrumentation are considered.