抄録
In this paper, the process leading to inception of surface discharge on organic insulating materials in atmosphere of fogs was investigated with particular attention on inception time. Fogs were formed by an ultrasonic vibration. Specimens used in this test were chroloplene-rubber (CPR), epoxy resin (EX), polycarbonate (PC), polystylene (PS) and phenolic paper laminate (KPL). In part, a piece of ceramic insulator was used.
The mean radius of fogs formed by the ultrasonic vibration is about 4.5μm, and the size and frequency distribution of the fogs are the same as fogs formed by radiation cooling. With increased exposure to the fog, a large number of droplets are formed on the specimen due to mutual collision and combination among the droplets.
A glow-like discharge initiates locally across a dry belt formed by Joule heat several 10 msec several sec after the droplets had bridged across the electrodes, the time depending upon, the applied voltage. The relation among specimens for the inception time of surface discharge is given by
CPR_??_EX>PC_??_PS>KPL<Ceramic insulator. This tendency corresponds with that of the contact angle among specimens.
