Standards for measuring the power factor of dielectrics at high voltage and low frequency

This paper points out the need which exists in the electrical industry; particularly in connection with the testing of high-voltage cables for convenient standards for use in the measurement of dielectric loss. At present most laboratories make use of air condensers. In the paper these are classified and certain sources of error which must be guarded against are mentioned. Condensers with solid dielectrics would be much more convenient, more portable, and cheaper, but so far none have been produced which have satisfactory constancy for use as standards at high voltage.