Composition Requirements and High Mechanical Strength of EI Cores

EI cores are generally manufactured using silicon steel sheets. Silicon steel is a type of steel containing silicon (also known as silicium), with a silicon content ranging from 0.8% to 4.8%. Silicon steel is used for transformer cores because it is a highly permeable magnetic material. When used in energized coils, it can generate a high magnetic flux density, thereby reducing the overall size of the transformer.

In EI cores, the core limbs and yokes are not in the same plane. Their structural configurations include radial, involute, and symmetrical types. Because the magnetic flux is distributed relatively evenly, core losses can be reduced. In contrast, planar cores have their limbs and yokes in the same plane, which provides high mechanical strength and excellent manufacturability.

EI cores are laminated cores assembled from stacked sheets. There are various types of wound cores. In involute cores, the air gap between the core limbs and yokes is relatively large, which affects the no-load current; therefore, their capacity cannot be too small. However, because the leakage flux enters the plane of the core laminations perpendicularly, it increases additional losses. Thus, the width of the sheets should not be too large, meaning their capacity cannot be excessively high.

EI cores primarily consist of the core body, clamping hardware, and insulating components:

1. Core body (magnetic conductor): Made of electrical steel sheets.

2. Clamping hardware: Includes clamps, bolts, glass fiber binding tapes, rigid binding straps, and spacer blocks.

3. Insulating components: Include clamp insulation, insulating tubes and pads, grounding straps, and feet.