ABSTRACT
The basic processes which lead to the electrical breakdown of gases were summarized in chapter 2. Air is the most commonly used gaseous insulation medium in high voltage power networks because it is free, is abundant and becomes self-restoring after a breakdown. Thus, electrical breakdown behavior of air is very important for designers and operators of high voltage equipment. For this reason, electrical breakdown and prebreakdown of air gaps have been thoroughly investigated since the start of this century and a vast amount of literature and data are available on this subject. Based on such information, international recommendations for air clearances have been established and are being used for the design of air insulated, high voltage power lines and other equipment. This chapter provides a brief summary of the breakdown characteristics of air gaps and the most important factors which can influence air insulation characteristics from the power system engineer’s point of view.
