An experimental 350-kv 1-picofarad air capacitor

This paper describes the design, features, and performance of a 1-picofarad 350-kv (rms), atmospheric-pressure air capacitor. Built in 1961 in the High Voltage Laboratory of the National Bureau of Standards, it is a part of a continuing program of high-voltage measurements, at power frequency, using capacitance ratio dividers. The immediate need was for its use in an interlaboratory comparison test of a 359-kv voltage ratio transformer, between the National Research Council of Canada and the National Bureau of Standards. The present paper supplements another paper which describes this test.¹ Details of the complete capacitance divider, and of the measuring bridge and its use, are contained in this reference. The capacitor was considered to be an interim item which, besides filling the immediate need, would give experience with the method and test the capacitor design.