Some applications of instrument transformers

Methods and apparatus are described in this paper for the measurement of amperage, voltage, and wattage, and for the calibration of meters and instrument transformers, by means of multirange precision transformers of special design. These methods are said to obviate the use of the multiplicity of primary standards commonly used in standardizing laboratories and to reduce the work of maintaining substandards in calibration. The methods and apparatus described have been used extensively in the laboratory and field by a large western power company; one of the principal benefits has been a noticeable improvement in the average accuracy of watt-hour meters on the system.