Improvement of signal to noise ratio in partial discharge measurements

In some cases of partial discharge (PD) measurements it is necessary to improve the signal-to-noise and disturbance ratio, particularly when the measurements are to be carried out on large capacitance objects. The paper presents the partial discharge measurement method based on signal theory. The measuring system presented in the paper can be used in such conditions. It is based on the method of multiple accumulation and averaging of the detected signal, which is the sum of the disturbance signal and of the partial discharge one. After such averaging the PD signal-to-noise-and-disturbance ratio increases and the phase location of the partial discharge signal can be distinguished from the disturbances and noises. The essential theoretical conditions of application of this method are discussed. The computer-aided system for data acquisition and following evaluation is described. The measurement results obtained in controlled model conditions are presented. The discussion of resultant improvement of signal-to-noise and disturbance ratio is given. The critical comparison with other methods which are being used for this aim is presented.