This type of current transformer is fully enclosed structure with epoxy resin cast outdoors. It is suitable for power system with rated frequency 50Hz or 60Hz and rated voltage 35KV and below. It is used for energy metering, current measurement and relay protection.  This product iec18521GB12085-2006 "current transformer" standard Current transformer have the whole-sealed structure with epoxty resin as its main insulation. Its core adopts the crystallitic alloy or excellent silicon steel sheets to enwind becoming annular, then secondary leads are enwinded on it evenly. Primary conducts are winded by insulation belt to avoid short circuit between conducts. There are earth bolts and holes suitable for mounting on the bottom of the product suitable the mounting 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.