Electrical steel is generally used to make original components of motors and transformers. Motors, transformers and other electrical components are generally required to have high efficiency, low power consumption, small size and light weight. Electrical steel plates usually use core loss and magnetic induction intensity as the guaranteed magnetic properties of the product. The performance requirements for electrical steel plates are as follows.
Requirements for magnetic anisotropy
The motor works in a running state. The iron core is composed of a stator and a rotor made of toothed circular punched sheets. The electrical steel plate is required to be magnetically isotropic, so it is made of non-oriented cold-rolled electrical steel or hot-rolled silicon steel. Generally, it is required that the difference in vertical and horizontal iron losses is less than 8%, and the difference in magnetic induction is less than 10%.
The transformer works in a static state. The cores of large and medium-sized inductors are made of laminated strips. Some distribution transformers, current and voltage transformers, and pulse transformers are made of wound cores. This ensures cutting and magnetization in the rolling direction of electrical steel plates. Therefore, All are made of cold-rolled oriented silicon steel. Some small transformer cores are made of E-1 type punched sheets, which can only ensure that the yoke of the punched sheets is magnetized along the rolling direction. In addition to being made of oriented silicon steel, non-oriented electrical steel is also commonly used. The stator core of a large steam turbine generator can also be punched into sector-shaped wells of oriented silicon steel plates and overlapped into a circular core, so that the yoke of the sector-shaped sheets is parallel to the rolling direction of the steel plate and the teeth are perpendicular to the rolling direction.
Good film processing performance
Users have a heavy workload of punching and shearing when using electrical steel plates. A small motor core requires thousands of 0.50mm thick punched sheets to be stacked. The stator core of a 600MW turbine generator is made of hundreds of thousands of 0.50mm thick sector-shaped punched sheets, which requires about 400t of high-grade non-oriented silicon steel. The core of a 360MV·A power transformer is made of about 100,000 0.35mm or 0.30mrn thick strips, requiring more than 300t of oriented silicon steel. Therefore, the electrical steel plate should have good punching properties, which is especially important for micro and small motors. Good punching performance can increase the life of the punching die and scissors, ensure accurate punching and shearing sheet dimensions, and reduce punching and shearing sheet burrs. Burrs cause short circuits between laminations and reduce the lamination coefficient (that is, the effective use of space in the core).