... TN-S, TN-C-S, TT, IT etc. power supply system of AC 50/60Hz, <440V, installed on the joint of ... release will help electric equipments separate from the power supply system and give the indication signal, green means normal, red means ... -D20/4P-385, 8 pieces.Main Technical Parameters Surge Protection Device CAN-D20Max. Continuous Operating Voltage Uc (V~)275V320V385V420V440VVoltage Protection Level ...