An electromagnet consists of a piece of iron or steel surrounded by a coil. The metal becomes magnetic when an electric current is passing through the coil. The iron is normally shaped into a bar or a hoof so that the core is easier to be magnetized. What’s more, in order to demagnetize the electromagnet immediately after power off, soft iron or silicon steel material are preferred.
Electromagnets are divided into two types: DC electromagnets and AC electromagnets. According to the purposes, they can also be divided into below five types: (1) Traction electromagnets—mainly used to pull mechanical devices, open or close various valves, and perform automatic control tasks. (2) Lifting electromagnets - used as lifting devices to lift ferromagnetic materials such as steel ingots, steel materials, and iron sand. (3) Braking electromagnet—mainly used to brake the motor to achieve the purpose of accurate parking. (4) Electromagnetic systems of automatic electrical appliances - such as electromagnetic systems of electromagnetic relays and contactors, electromagnetic trippers of automatic switches and operating electromagnets, etc. (5) Electromagnets for other purposes - such as electromagnetic chucks of grinders and electromagnetic vibrators.
What is the principle of electromagnets?
When the iron is inserted inside the energized coil, it is magnetized by the magnetic field that surrounding the energized coil and turns out to be a magnetic object. The magnetism of the energized coil is greatly enhanced due to another new magnetic field that comes from the magnetized iron. In order to make the magnetism of the electromagnet stronger, the iron core is usually shaped into a hoof, However, it is noted that the winding direction of the coil on the shoe-shaped iron core should be opposite that one side is clockwise, and the other side must be counterclockwise. If the winding directions are the same, the magnetization to the iron from the two coils will be neutralized, and the iron will not be magnetic any longer. What is more, the iron is made from soft iron but not steel as the steel will remain the magnetism for a long time and cannot be demagnetized once it is magnetized, and the advantages of electromagnets will be lost because the magnetic strength of the iron cannot be controlled by the magnitude of the electric current,
An electromagnet is an assembly that can generate a magnetic force by passing electric current, which is a non-permanent magnet and can be easily activated or deactivated. For example, Large cranes use electromagnets to lift abandoned vehicles.
When electric current is passing through a wire, a magnetic field forms around the wire. In the same way, when an electric current is passing through a coil, a magnetic field forms within the coil. Assuming that a ferromagnetic substance is placed in the center of the coil, the ferromagnetic substance will be magnetized and the magnetic field will be greatly enhanced.
Generally speaking, the magnetic field produced by an electromagnet is related to the effect of the electric current, turns of the coil and the center iron. More attention paid to the distribution of coils and the selection of the iron during the design of electromagnets, and magnetic field controlled through the effect of the electric current. The effect of the magnetic field is limited as there is a resistance in the coil material However, with the discovery and application of superconductors, there will be more opportunities to get the better of the existing limits.
What are the advantages of electromagnets
- Magnetism is controlled by the electric current
- The magnetic performance can be controlled the effect of the electric current ,turns of the coil or the resistance
- Magnetic poles can be controlled by the change of the direction of electric current
Electromagnets are used in cranes, telephone, ammeter, voltmeter, galvanometer, packaging machinery, medical equipment, food machinery, textile machinery, electromagnetic relay and Maglev train.