抄録
This paper deals with the study on the possibility of an aerial flashover between a coil conductor and a casing in rotating machines under an application of lower voltage compared with Paschen's voltage even when enough insulation distance is secured. The time lag to aerial flashover originated from surface flashover was measured. To understand the aerial flashover influenced by the parameters of voltage application circuit, the aerial flashover distance was measured using cable which had a simulated pore to confirm the above consideration. A surface flashover characteristic was also measured using a photomultiplier tube (PMT). It became clear that the aerial flashover occurred at about a few milliseconds after the surface flashover generation. After showing the peak, the aerial flashover distance decreased with increasing time constant. The surface flashover time estimated by PMT output exhibited the different values with the change of a capacitance when the time constant is larger. On the other hand, the average surface flashover current was almost the same in spite of the change of a capacitance. Form these results, it was considered that the aerial flashover distance was influenced by time constant of circuit.
