This type of voltage and current combined transformer (measuring box) is used for AC 50Hz, rated voltage 20KV three-phase line, for voltage, current and energy measurement and relay protection. It is suitable for outdoor substations of urban power grids and rural power grids, and can also be used for various transformer power distribution stations in industrial and mining enterprises. The combined transformer is equipped with active and reactive watt-hour meters, which is called a high-voltage power metering box. This product can replace the oil-immersed combined transformer (metering box). (1) combined transformers are assembled from dry single components, and there is no oil leakage problem, so oil-free is realized; (2) The voltage and current are all cast with resin, like a building block structure, which is easy to replace, easy to maintain, and saves costs; (3) The product has high precision, and the current transformer can reach 0.2S level, which realizes wide load measurement; (4) The use of materials makes the product have high dynamic and thermal stability; (5) The voltage part can be equipped with a 220V auxiliary winding to provide power for switches, etc. Conditions of Use: 1. The ambient temperature is between -45°C and 40°C, not exceeding the daily average temperature of 35°C; 2. The altitude does not exceed 1000 meters (please provide the altitude when using in high altitude areas); 3. Wind speed: ≤34m/s; 4. Relative humidity: the daily average is not more than 95%, and the monthly average is not more than 90%; 5. Shock resistance: horizontal acceleration 0.25g, vertical acceleration 0.125g; 6. This product can run for a long time at 1.2 times the rated voltage factor; 7. Device category: outdoor composite insulation fully enclosed structure;