An Improved Method for Calculating the Impulse Strength of Wood Porcelain Insulation

This paper describes an improved method of predicting the breakdown voltage and volt-time characteristic of wood-porcelain combinations. The model accounts for the different voltage waveshapes that stress each element of the combination. The integration method is used to evaluate the breakdown and the time to breakdown of each element, from which are derived the insulation strength and the volt-time characteristic of the combination. This method can reproduce laboratory results to within 10 percent for a wide range of wood-porcelain combinations.