Measuring dissipation and dielectric constants

THE VARIATION of susceptance method of measuring dissipation factor has been described by Hartshorn and Ward.¹ This article describes apparatus and technique designed to increase the speed and, under certain conditions, the accuracy of this method by reducing the number of manual adjustments and instrument readings normally required in its application. A recording meter is employed to obtain traces of the resonance curves for the circuit with and without the dielectric specimen. This is done by having a constant-speed motor-driven capacitor tune the circuit through resonance while a recording milliammeter operated from the vacuum-tube voltmeter traces the voltage resonance curve. Limit switches operate relays which reverse the motor at each end of the travel of the micrometer tuning capacitor, so that the circuit is automatically tuned back and forth through resonance. During the test it is necessary to make only two readings, the settings of the specimen capacitor with and without the specimen in place and to make only one accurate manual capacitor setting for resonance. The resonance curves can be examined at leisure and the computations can readily be made from them. A permanent record of the test is obtained.