... ac power 2.working voltage: 220V /380V AC 3.1,2,3,4P(+NPE) 4.ISO9001 5.8 years experience 3 Level Power-supply Module ... (4P,3P+NPE) surge protector for ac power 1. Third level protection2. install ... standard plug-in modular design, easy installation, simple maintenance, module degradation indication, automatic switching off at exit failure and recovery ...