The calibration of inductors at power and audio frequencies

A brief description of the standard inductors at the National Physical Laboratory is given. The principal characteristics of self- and mutual inductors are then considered in relation to their measurement. The methods of inductance measurement at the N.P.L. are described; these include the calibration of mutual and self-inductors, the measurement of their variation with frequency, the a.c. resistance of inductors, and the components of self-capacitance. Emphasis is given to the precautions necessary to ensure precision.