A Precision Current Transformers Used for Audio Frequency Power Standard

A precision current transformer of audio frequency has been developed, in which an auxiliary current transformer is introduced to equalize the potential along the primary and secondary winding of the main current transformer, resulting a dramatic reduction of capacitive leakage current. In this way, a ratio error less than 10 ppm and phase angle error less than 10 rad have been achieved at the frequency up to 15000 Hz.