Lightning Protection / Earthing Screen

[sky72]

I need some information about earthing screen which protect the outdoor equipment (high voltage switchgear - conventional type/air insulated) from direct lightning strikes.

The earthing screen required to cover the whole plant using graphical methods (Rolling Sphere Method).

Appreciate somebody can provide the guideline of Rolling Sphere Method.

Thanks.

 

[jghrist]

IEEE Guide for Direct Lightning Stroke Shielding of Substations, IEEE Std 998-1996

Abstract
Design information for the methods, historically and typically applied by substation designers to minimize direct lightning strokes to equipment and buswork within substations is provided. Two approaches, the classical empirical method and the electrogeometric model, are presented in detail. A third approach involving the use of active lightning terminals is also briefly reviewed.

The electrogeometric model is the "rolling sphere" method.