IEEE Std 998-1996 IEEE Guide for Direct Lightning Stroke Shielding of Substations references
A Computer Program for Designing the Lightning Shielding Systems of Substations, Mousa, A.M., IEEE Transactions on Power Delivery, Jan. 1991
Abstract
A computer program is presented for designing the shielding systems of substations. The program is based on the most up-to-date version of the electrogeometric model (EGM). The calculation method is made free from the conservatism of some earlier versions of the EGM by introducing rational revisions. Shielding designs for typical layouts are also presented.
This is partly based on the Mousa program. I've used an earlier version and find it somewhat restrictive on what layouts can be analyzed. I prefer to use the rolling sphere method and use Mathcad to analyze different layouts. This is much more flexible, but difficult. You can determine areas protected by non-parallel shield wires, three masts of different heights, as well as the more simple configurations analyzed in IEEE Std 998.
If you are designing lightning shielding systems for outdoor substations in accordance with the IEC standard, then you need the new British standard BS EN 62305 for protection against lightning.
For your information BS EN 62305 WILL replace BS 6651 in September 2008. Currently the two standards are running in parallel with one another and therefore our information on BS 6651 and software produced for this standard can still be used at this time.
This new standard has a significant impact on all those involved in the design and installation of lightning protection on structures.
The vendor, Furse StrikeRisk Software Version 4.0 should prove invaluable to those of you involved in risk assessment calculations. I tried this software and the calculation results is acceptable to our clients in the oil and gas industry.