Electromagnets are extremely widely used in everyday life. Electromagnets are an application of current magnetic effects (electro-magnetic) and are closely related to life, such as electromagnetic relays, electromagnetic cranes, maglev trains, etc. Electromagnets can be divided into two types: DC electromagnets and AC electromagnets. If the electromagnets are divided according to the purpose, they can be mainly divided into the following five types: (1) Traction electromagnets - mainly used to pull mechanical devices, open or close various valves to perform automatic control tasks. (2) Lifting electromagnets - used as lifting devices to lift ferromagnetic materials such as steel ingots, steel, and iron sand. (3) Brake electromagnet - mainly used to brake the motor to achieve accurate parking. (4) Electromagnetic systems of automatic electrical appliances - such as electromagnetic systems of electromagnetic relays and contactors, electromagnetic trips of automatic switches, and operating electromagnets. (5) Electromagnets for other purposes - such as electromagnetic chucks for electromagnetic machines and electromagnetic vibrators.