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. This product is assembled from dry single components, and there is no leakage problem, so it is oil-free. 2. The voltage and current are all cast with imported resin, which is like a building block structure, which is easy to replace, easy to maintain and save 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 special materials enables the product to have high dynamic and thermal stability. 5. The voltage part can be equipped with a 220V auxiliary winding to provide power for switches, etc. Applicable working conditions: 1. The height above sea level is not above 1000m. (Please indicate height above sea level if it is used in high land area). 2. Max.change of environment temperature doesn't exceed 5℃ to 40℃. (If there is any requirement. Please indicate in the order). 3. Ordinary products can be used in the area with relative humidity not above 85%. 4. There is no gas, steam, chemical sedimentation, dust or dirt or other explosive and corrosive medium that seriously affect transformer at installation site. There is no serious vibration or bump. Either.Ordering instructions: 1. Model, name and quantity of circuit breakers; 2. The rated voltage, rated current and rated short-circuit breaking current of the circuit breaker; 3. Circuit breaker shell material; 4. The operation mode of the operating mechanism (manual, electric, with remote control), the type and rating of the operating current; 5. Accuracy, transformation ratio, and quantity of current transformers; determine zero-sequence transformers, voltage transformers, etc. 6. The name and quantity of spare parts and spare parts; 7. If users have special requirements, please explain them when ordering. Precautions: 1. When the primary current passes through the current transformer, the secondary winding is not allowed to open circuit, otherwise high voltage will be generated, which will affect the performance of the product. 2. The secondary winding of the voltage transformer is not allowed to be short-circuited. Otherwise it will burn the transformer. 3. The repeated power frequency withstand voltage test of the primary winding shall be performed at the specified test voltage.80% of the value.