Function of Insulating Paint on Transformer Core
Sep 10, 2022
The iron core of the transformer constitutes the magnetic circuit of the transformer and plays the role of the skeleton of the body. The transformer core is generally made of 0.35mm thick silicon steel sheets coated with insulating paint. The iron core is coated with insulating paint mainly to reduce core loss:
1. Silicon steel sheet itself is also a conductor. Under the action of AC magnetic flux, induced current is also generated in the iron core.
2. If the iron core is not coated with insulating paint, it will become a whole, which is equivalent to a conductor with a large area. Its resistance value is small. Although the induced voltage is not high, the induced current is large. This will cause great eddy current (circulating current) loss. In serious cases, it will make the iron core hot or even the rust melt, which is called "fire" of the iron core.
3. After insulating paint is applied between each piece, the iron core is divided into many conductors with small section. The resistance becomes larger. The painted iron core also has eddy current loss (a part of the iron loss), but it is much smaller.
4. Therefore, silicon steel sheets are thin and should be coated with insulating paint.
