Lightning and surge protection of substations

Lightning and switching transients along with ground faults create significant voltage anomalies on transmission and some distribution circuits. Not only direct strikes, but nearby strikes, create significant voltage anomalies and subsequent line outages. Developments have made it possible to provide a solution to lightning and surge problems, and also reduce the overall cost of substation designs. It is now possible to prevent lightning strikes to any substation component (including the protection system), and to limit incoming transient voltages to as little as 10% over their normal sine wave peaks. This paper defines the problem confronting protection systems engineers, reviews the protection systems conventionally used and defines two new protective systems: the Dissipation Array System (DAS) and the series hybrid forms of surge protection. The DAS has been in use for over twenty years as a strike preventer. The series hybrid protection concept is new to substation applications, but has been in use at secondary levels of up to 2500 V for approximately sixteen years. As a result, lightning or other forms of transient phenomena does not need to be a threat to substations or drive up the overall costs