I have some questions regarding the design of lightning system for ACC platform. I was wondering if it is possible for you to help me on the issue.
The questions are as follows:
1- Do ACC platforms need any protection against lightning? And if yes, how are they protected? Which kind of protection is more appropriate for this structure (conventional LPS or E.S.E)?
2- As you know, according to IEC 62305-3, metal parts of a structure(under specific condition) should be considered, and may be used, as natural air termination components and part of an LPS or may be used as the down conductors.
In case of using the natural components of the ACC (piping and steel structure) as parts of LPS, when lightning flashes occur do the equipment bonded to it remain safe and protected, or they may subject to damage? For example, may lightning current pass through the tube bundles and fan motors, which are electrically connected to structure and cause any damage?
It should be mentioned that all metal parts and equipment of the ACC steel structure are electrically bonded to the structure and we usually connect the structure to ground at least in four different points. Besides, all existing electrical and I&C equipment are also connected to secondary earthing system and are grounded. Main grounding system contains grid meshes which spread over whole power plant with relatively low resistance.

It would be great if you could inform us about your solution and method of lightning protection system for ACC platforms.