Internal discharges in dielectrics: their observation and analysis

Previous work on the observation of discharge phenomena is reviewed briefly. Methods used by the authors are described, together with means of determining the quantitative significance of the results. It is shown that the h.f. discharge detector is sensitive and convenient in use, while the oscillograph bridge is more informative. The theory of the sequence of discharge on alternating current is developed in the light of experimental observations and yields values for the energy loss in an idealized case in accordance with experiment. Some consideration is given to the choice of method appropriate to various cases, and the sensitivities of a number of methods are compared. The application of discharge detection to two particular cases is described, and the relationship between discharge characteristics and life under certain conditions is established.