Impulse test classification of surge protective device

class I tests
tests carried out with the impulse discharge current Iimp, with an 8/20 current impulse with a crest value equal to the crest value of Iimp, and with a 1,2/50 voltage impulse

class II tests
tests carried out with the nominal discharge current In, and the 1,2/50 voltage impulse

class III tests
tests carried out with the 1,2/50 voltage - 8/20 current combination wave generator