A detailed study on high-voltage capacitor dielectric system under multistress conditions

This paper presents the results of a detailed study conducted using model capacitors and dielectric film to estimate the service life and the interaction behaviour of film and the impregnant. Model capacitors were prepared using films procured from different sources and subjected to accelerated ageing. The working life of HT capacitors at 25°C and 50 volts/micron stress is found to be above 30 years. The effect of temperature on the design of the model capacitor is discussed. A relatively new short-term technique of life estimation of film by continuous constant stress application has been studied. A new phenomenon of the formation of liquid-droplets on the film surface in this test was observed. The causes for this are discussed