三相四线制零线断保护装置彭通光璧山县水电局理论分析和实践证明，在三相四线制低压系统中，如果零线断开，则负载较大一相的电压要低于２２０Ｖ；负载较小一相的电压要高于２２０Ｖ，有烧毁用电设备的危险。在实际运行中，经常遇到国零线断开而烧坏家用电器的例子。为此... Three-phase four-wire zero line protection device Peng Tongguang Bishan County Water Power Bureau theoretical analysis and practice proved that in the low-voltage three-phase four-wire system, if the zero line is disconnected, then the load voltage of a larger phase less than 220V ; The voltage of a smaller load is higher than 220V, there is the danger of burning electrical equipment. In the actual operation, often encountered in the national zero line disconnect and burn out household appliances example. to this end...