What matters should be paid attention to when selecting a cast resin power transformer?
Dry-type cast resin power transformers have developed rapidly around the world. With the development of China's modernization construction, the load of urban and rural power grids continues to increase.
Notes on choosing the type of dry-type cast resin power transformer:
1. Temperature control system of dry-type transformer The safe operation and service life of dry-type transformers depend to a large extent on the safety and reliability of transformer winding insulation. The temperature of the coil exceeds the insulation withstand temperature and the insulation damage is one of the main reasons why the transformer cannot work normally. Therefore, the monitoring and alarm control of the operating temperature of the transformer is very important.
2. The protection method of dry-type cast resin power transformers According to the characteristics and protection requirements of the use environment, dry-type transformers can choose different outer packaging. Usually choose IP20 protective shell, which can prevent the entry of solid foreign objects larger than 12mm in diameter and small animals such as mice, snakes, cats, and sparrows, causing vicious failures such as short circuit and power failure, and providing a safe barrier for live parts. If the transformer is installed outdoors, you can choose an IP23 protective enclosure. In addition to the above IP20 protection function, it can further prevent the entry of water droplets within a vertical line and an angle of 60°. However, the IP23 frame reduces the cooling capacity of the transformer, and it is necessary to pay attention to the reduction of its operating capacity when selecting.
3. Cooling method of dry-type transformer The cooling method of dry-type transformer can be divided into natural air cooling (AN) and forced air cooling (AF). When the natural air is cooled, the transformer can run continuously for a long time under the rated capacity. In forced air cooling, the outlet capacitance of the transformer can be increased by 50%. It is suitable for intermittent overload driving or overload driving caused by accidents; when overloaded, the load loss and impedance voltage increase greatly, and it is in a non-economic operation state, so it should not be continuously overloaded for a long time.
Fourth, the overload capacity of the dry-type cast resin power transformer is related to the ambient temperature, the load condition before overload (starting load), the insulation thermal condition of the transformer and the heating time constant.
