WCB-820 series (including WCB-821 and WCB-822) microcomputer factory variable protection measurement and control device is mainly suitable for 3 ~ 10kV voltage level small ground current system or small resistance ground system in the plant variable, used or ground change protection. Rated data a. Rated power supply voltage: DC220V or DC110V or AC220V (the order indicates that AC220V is used in AC operating loop)b. Rated AC data: AC voltage: 100/ V, 100V zero sequence voltage: 100V AC current: 5A or 1A(order indicate) Zero sequence current on high voltage side: 1A or 5A(order indicate) Zero sequence current on low voltage side: 5A Rated frequency: 50Hz