Atmospheric variations and apparatus flashover

I. Introduction IN practically all electrical apparatus use is made of the insulating properties of air. The electrical breakdown strength of air, for the electrode arrangements found in apparatus, depends upon air temperature, pressure and moisture content. This condition has long been appreciated and recognized in various standards for testing and for determining insulation ratings. However, the range and significance of the extreme conditions encountered, is not always appreciated. It is proposed, therefore, to consider the variations found in actual service and determine how well current standards and application practices cover these variations. In addition, the desirability of uniform application practices and reference ranges for different apparatus is suggested.