The iron core of a transformer constitutes the magnetic circuit of the transformer and also serves as the skeleton of the body. The transformer core is generally made of silicon steel sheets with a thickness of 0.35mm and coated with insulating paint on the outer surface. The primary purpose of applying insulation paint to the iron core is to reduce iron core loss, primarily due to the following reasons:

1. Silicon steel sheets themselves are also conductors, and under the effect of alternating magnetic flux, induced currents are also generated inside the iron core.

2. If the iron core is not coated with insulating paint, it will become a whole, equivalent to a conductor with a large area and low resistance. Although the induced voltage is not high, the induced current is large. This will result in significant eddy current (circulation) losses. When severe, it can cause the iron core to heat up and even rust to melt, known as iron core "fire".

3. After applying insulation paint between each piece, the iron core is divided into many small cross-sectional conductors. So its resistance increases. The painted iron core, although also experiencing eddy current losses (which are a part of iron losses), is much smaller.

Article source: Transformer silicon steel sheethttp://www.cheungshun.com/