Power Arc Protective Fittings for Composite Long Rod Insulators

Abstract

Various factors determine whether or not power arc protective fittings need to be used. Network parameters such as the current, duration and frequency of a short circuit are very influential. However, the basic set-up of the insulator string is also significant: Here, it is necessary to differentiate between the cap and pin design and the long rod design, which behave differently when there is a power arc and therefore influence the philosophy of power arc protection. Composite insulators have a long rod design. Unlike porcelain long rod insulators, however, they have the distinctive feature of being able to be manufactured in one piece without any intermediate fittings, even for the highest voltage levels. As a result of this classification, many "power arc" experiences and rules associated with porcelain long rod insulators also apply to composite long rods. There is also one notable difference: The slenderness of the composite long rods results in smaller fitting diameters, which makes it necessary to protect the insulator against corona at lower transmission voltages and can require a coordination of corona and power arc protection. © Springer-Verlag Berlin Heidelberg 2013.