FZW28-12F series outdoor demarcation vacuum load switch is suitable for outdoor three-phase AC power distribution system with rated voltage of 12KV and rated frequency of 50Hz, used for opening and closing load current and closing short-circuit current. FZW28-12F series outdoor demarcation vacuum load switch is suitable for substations, industrial and mining enterprises and automatic distribution networks of urban and rural power grids for protection and control, and places with frequent operations. This product can also be used for the operation control switch for overhead line power distribution system. There are various types, with outstanding advantages such as oil-free, simple structure, reliable performance, and no maintenance. It has been widely used so far. The product is combined with FDR type fault detector or RTU remote control terminal device and other equipment to form a distribution automation system with a simple structure, which can realize automatic location of overhead line faults and automatic isolation of fault sections. In order to update the existing distribution switchgear and make it realize the need for the transformation of distribution equipment characterized by oil-free and automation. Automatically cut single phase earthing fault : when users tributary line cause single phase earthing fault, the boundary switch will open automatically, other distribution line users of the substation and feeding line will be without influence; isolation interphase short circuit fault automatically. When the tributary line cause interphase short-circuit fault, boundary switch will open at once after out-wire protection tripping. After the substation reclose, fault line is isolated passively,other distribution users in feeding line resume power supply rapidly(equal to a transient fault). Quick localization of fault: the tributary line fault cause boundary switch protection action, only the accident user cause power cut and by itself report the fault information, the power company could dispatch worker to life investigation;if the boundary switch match with communication module, it could transmit message to electricity management center. Monitoring users load, boundary switch could configure wired or wireless communication enclosure to monitor data and transmit to electricity management center,make the achievement of real-time data monitoring of users load in long distance. Function of network running, it could be used in network lines,function of measurement,monitor voltage,current,frequency and quantity of electricity of lines,and transmit to management center in long distance.Function of harmonic analyzing to supply reliable basis for pollution administration of electricity net afterwards.Ambient temperature:-10ºC-+40ºC Relative humidity:The average humidity of a day should be no more than 95%. The average humidity of a month should be no more than 90%. Earthquake intensity: not exceed 8 degrees. Saturated vapor pressure the average pressure of a day should be no more than 2.2kPa; the average pressure of a month should be no more Than1.8Kpa; The height above sea level:≤1000 m (Except special requirements) It should be installed in the places without fire, explosion, serious filth, and chemical erosion and violent vibration.