To wind a power transformer, we must have a certain understanding of the materials related to the power transformer. Therefore, I will introduce this knowledge here.
1. Core material
The core materials used in power transformers mainly include iron sheets, low silicon wafers, and high silicon wafers. Adding silicon to steel sheets can reduce their conductivity, increase their resistivity, and reduce eddy currents, resulting in reduced losses. We usually refer to steel sheets with added silicon as silicon steel sheets. The quality of silicon steel sheets used in power transformers is closely related to their quality. The quality of silicon steel sheets is usually represented by magnetic flux density B. Generally, the B value of black iron sheets is 6000-8000, low silicon wafers are 9000-11000, and high silicon wafers are 12000-16000.
2. The materials commonly used for winding power transformers
Lacquered wire, yarn wrapped wire, silk wrapped wire, the most commonly used enameled wire. The requirements for wires are good conductivity, sufficient heat resistance of the insulation coating, and a certain degree of corrosion resistance. In general, it is best to use high-strength polyester enameled wire of QZ model.
3. Insulation material
In the winding transformer, insulation materials are used for the isolation between the coil frame layers and between the windings. Generally, the frame material of the power transformer can be made of phenolic cardboard, and the insulation between the layers can be made of polyester film or telephone paper. The insulation between the windings can be made of yellow cloth.
4. Impregnating material
After the power transformer is wound, it still needs to go through the last process, which is to impregnate the insulation paint. It can enhance the mechanical strength, improve the insulation performance, and extend the service life of the power transformer. Generally, cresol varnish can be used as the impregnating material.
