The commonly used transformer core is generally made of silicon steel sheet. Because the silicon steel itself is a magnetic material with strong magnetic conductivity, in the energized coil, it can produce a large magnetic induction intensity, so that the volume of the transformer can be reduced.
As we know, the actual transformer always works in the AC state, the power loss is not only in the resistance of the coil, but also in the core under the alternating current magnetization. The power loss in the iron core is usually called "iron loss". The iron loss is caused by two reasons, one is "hysteresis loss" and the other is "eddy current loss".
Hysteresis loss is the iron loss caused by the existence of hysteresis phenomenon in the process of magnetization of the iron core. The size of this loss is proportional to the size of the area surrounded by the hysteresis loop of the material. The hysteresis loop of silicon steel is narrow, and the hysteresis loss of transformer core is small, which can greatly reduce its heating degree.
Varelen's transformer, The three-limb iron core is made of oblique cut Grain-oriented, seven-step silicon steel laminations insulated on both sides, guaranteeing low losses and low noise. These values are even improved by laser treatment. It is protected on the surface with a flash-proof varnish in order to prevent the sheet from corrosion and to reduce the noise.
Distribution Transformers use silicon steel sheets for the iron core mainly because of their excellent electrical and magnetic properties, which help improve efficiency and reduce energy losses. Here are the key reasons:
1. Reduced Eddy Current Losses
- Silicon steel has high electrical resistance, which minimizes eddy currents. Eddy currents are loops of electric current induced within the core by the alternating magnetic field. These currents lead to energy loss in the form of heat.
- By using thin silicon steel sheets, the core is laminated, which breaks the path of eddy currents, thereby reducing these losses significantly.
2. Low Hysteresis Losses
- Silicon steel exhibits low hysteresis loss, meaning less energy is wasted when the magnetic field within the core changes direction. This is crucial because the transformer's operation involves continuous changes in the magnetic field, especially in AC systems.
- The addition of silicon to steel helps in reducing these hysteresis losses, making the transformer more efficient.
3. High Magnetic Permeability
- Silicon steel has high magnetic permeability, allowing it to conduct magnetic flux more effectively. This means the material can easily magnetize and demagnetize, which is essential for the efficient transfer of energy in a transformer.
- High magnetic permeability also means that less magnetizing current is needed to generate the magnetic field, leading to improved performance.
4. Enhanced Durability
- The silicon content in the steel also makes it resistant to oxidation and corrosion, which helps in maintaining the core's properties over time. This enhances the transformer’s longevity and reliability.
5. Cost-Effective
- Silicon steel is cost-effective compared to other materials that might offer similar magnetic properties. Its availability and ease of manufacturing make it an ideal choice for transformer cores.
6. Temperature Stability
- Silicon steel can withstand high temperatures without significant degradation of its magnetic properties. This makes it suitable for transformers, which may operate under varying load conditions and temperatures.
