A system for the measurement of the loss tangent and capacitance of high-voltage insulation over a wide range of frequency and voltage

There is no need to determine the high-voltage characteristics of high-voltage insulation systems used in high-powered electrical machines in order to evaluate the relevance of 0.1 Hz measurements to those taken at power frequency and to investigate their value for diagnostic purposes. A computer-controlled system for the generation of test voltages and the measurement of loss tangent and capacitance in the range 1 mHz to 1 kHz and 100 V to 22 kV RMS is described. The high voltage generator is basically a class B amplifier with an output rating of 30 kV (peak) and 100 mA (peak). The measurement system is based on the analysis of the out-of-balance signal of a modified capacitance bridge. The accuracy of the system is discussed and measurements from samples of high-voltage conductor bar insulation used in turbo-generators are presented.