Insulation tests of transformers as in fluenced by time and frequency

Vladimir Kara pet off: For several years previous to his death, Dr. Steinmetz talked from time to time about third-class conductors and pyroelectric effects, and I often asked myself, why this interest in the third-class conductors. I did not see t he point until the appearance of his paper in the “Electrical World” giving the so-called pyroelectric theory of breakdown of insulation. At the same time, but independently from Dr. Steinmetz, Dr. Willy K. Wagner in Germany was working on the same subject. He came to this country on a visit in 1922 and read a paper (printed in the 1922 A. I. A. E. TRANSACTIONS) which for a long time will remain a classic on t he subject. In other words, where Dr. Steinmetz only had time to go into the theory qualitatively, Dr. Wagner also gave us at least a beginning of a mathematical theory of the breakdown of solid dielectric.