The importance of generator operating conditions on PD data evaluation

This paper summarizes the results of a preliminary study on the influence of generator operating conditions on its partial discharge (PD) activity. This study covers results from the field measurements as well as from laboratory investigations. The turbo generator discussed in this paper showed an extra PD source at high temperature. This extra PD source was activated at high temperatures and vanished at lower temperatures. The activation and the de-activation process had a clear hysteresis character. Both the measurements on the turbo generator and in the laboratory showed that there is certain dependence between the internal PD and the actual temperature of the stator coil. Due to the fact that in practice the moment at which a periodic measurement is performed does not always represent the PD activity of a generator under all its operating conditions, it is of practical interest to investigate the dependences between the power, temperature and the actual PD activity. A full investigation into the relation between generator operating conditions and its PD activity is justified.