Abstract :
WHEN any part of the air path included in the insulating circuit of a piece of electrical equipment is overstressed, ionization occurs. The critical value of voltage is a function of the nature of the remainder of the dielectric circuit, the manner of use, surface conditions, the proximity of grounded conducting bodies, the temperature, and in some cases, the relative humidity. Ionization in air causes the formation of small quantities of ozone and oxides of nitrogen. The presence of ozone leads to accelerated aging of insulating materials, especially organic materials such as varnished cambric and paper.
