... frequency:50-70Hz 3.Phase:three phase 4. Power type:AC AC Three-phase Surge Protector with 3 Wires1. Working principle HK ... ,Surge Suppressor,Overvoltage Protector,Thunder Protection,Electrical Control,System Protector, Direct Strick Protection, Power solutions,Surge Diverter,Thunder Arrester,Surge Absorber ...