Ignition Process of Attachment Plugs due to Thermal Deterioration

Abstract

In this paper, a process, from thermal deterioration to ignition, of an attachment plug due to joule heat of defective contact between socket receptacles and plug blades (both are of 2 poles) supplied with AC100V, is studied through experiments and a new ignition process is discussed.
This process proposed is as following. Defective contact causes heat, which thermally deteriorate on the surface and inside of PVC plug insulators. The severely deteriorated PVC undergoes dehydrochlorination due to pyrolysis and reacts with calcium involved, producing calcium chloride with high hygroscopic property. Due to this thermal deterioration, it is found that the insulation resistance between 2 blades drops to 10⁵ Ω order, and if kept as it is, drops further to 10³ Ω order due to water absorption on the surface and inside the PVC. Ignition experiments was performed through this process using the plug with dropped inlsulation resistance, and it is found that there is danger of ignition when insulation resistance between 2 blades drops to 10³ Ω order.