Registration experience of partial discharges in operating equipment with digital oscillograph

The paper discusses the measurement of partial discharges from AT-2 autotransformers, and also AT-3 and AT-4 groups, using digital oscillographs. The techniques of registration of PD differed for different objects according to available capabilities. For AT-2 the measured signals on CP of inputs of one class of voltage but different phases, and also signals on CP of inputs 220 and 110 kV of one phase were investigated. Thus the filtration of signals by series connection to circuit of high frequencies filters, and coordination of impedance of a cable with load was performed. During registration polarity and level of start of sweep, the scales on axes of the oscillograms changed. Finally the distinctive features of signals of a different kind of interference including corona, and PD were determined.