A precision transformer used for an audio-frequency power standard

A precision current transformer for the audio-frequency band in which an auxiliary current transformer equalizes the potential along the primary and secondary windings of the main current transformer is discussed. The arrangement results in a dramatic reduction of capacitive leakage current. In this way, a ratio error of less than 10 p.p.m. and phase angle error of less than 10 μrad is achieved at frequencies up to 10000 Hz