The Discharge Mechanism Leading to the Tracking Progress in Polyvinyl-Chloride-Sheathed Flat Cord

Abstract

Purposes This paper suggests the mechanism of the discharge phenomenon that leads to tracking progress. Methods For this purpose, a polyvinyl-chloride-sheathed flat cord (PVCSFC), which is widely used as a distribution cord, was employed and an artificial crack was intentionally made on the surface. Tracking was progressed using electrolyte droplets. The mechanism of the discharge phenomenon was suggested from the measurement and analysis of the current waveform. Results As carbonization progressed during the tracking progress, the frequency of scintillation discharge also significantly increased. The mechanism for scintillation discharge during the tracking progress was based on the change in the electric field of the dry band, initial electron, electron avalanche, photoionization, secondary electron generation (electron detachment, photoemission, and secondary electron emission avalanche), space charge due to positive ions, and formation of conductive channels. Conclusions This discharge mechanism could explain the physical phenomenon and change in the current waveform that occurs during the tracking progress.