I am interested to know how to calculate and select a right type of lightning arrestor. how the rating is selected? is it different for the earthed and unearthed system?
It is very dependent on which standard your application should comply. A popular device to do this work is sidactors. Please look at this link for some explenations:
Hello I am not interested in lightening at this time but your link to the littlefuse site is useful thanks Ian.
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There's them that knows and them that just thinks they know, whitch are you? Stir the pot and see what rises up. I have catalytic properties I get a reaction going.