... be replaced for the module. Product DescriptionNS1-(D, C, B) 5 series surge protection device (in short: SPD, ... system and give the indication signal, green means normal, red means abnormal, it also could be replaced ... Scope and Installation PositionNS1-(D, C, B)5 surge protective device is applicable for D, ... C,B grade lightening-proof, installed on the joint ...