Tag: 3 phase induction motor

An induction motor refers to an AC motor that relies on electromagnetic induction between the stator and the rotor to induce a current in the rotor to realize electromechanical energy conversion. The stator of the induction motor consists of three parts: the stator core, the stator winding and the frame. Under normal circumstances, the rotor speed of the induction motor is always slightly lower or slightly higher than the speed of the rotating magnetic field, so it is also called an "asynchronous motor".

Induction motor for sale, also known as "asynchronous motor", is a device that puts the rotor in a rotating magnetic field and obtains a rotating torque under the action of the rotating magnetic field, so that the rotor rotates. The rotor of an induction motor is a rotatable conductor, usually in the shape of a squirrel cage. According to the type of alternating current, there are single phase induction motors and Three phase induction motors. So what is the difference between them? This is mainly reflected in the following aspects.

Compared with other motors, the ATO induction motor has the advantages such as simple structure, convenience in manufacture, use and maintenance, high operational reliability, light weight, low cost. Taken the ATO three-phase induction motor as an example, compared with the DC motor with the same power and speed, the former weight is only half of the latter at one-third cost. It also has the load characteristics of constant speed that can satisfy machinery driving requirement of a majority of industrial and agricultural production. Its limitation is that due to the poor speed controlling performance caused by the fixed slip between its rotate speed and the synchronous speed of its rotating magnetic field, so it is not so economic or convenient as direct current motor under the usage occasion that requires a wider range of smooth speed control such as rolling mill, winding engine, large size machine tool etc. In addition, induction motors draw reactive power from the power system during the operation, resulting in the deterioration of power factor of power system. Therefore, on the occasion of high power and low speed such as driving ball grinding mill and compressor, using synchronous motors is more reasonable.

How does an 3-phase induction motor work? In short, it works based on the principle of electromagnetic induction. When the stator windings are supplied with three-phase alternating current, a rotating magnetic field is generated between the stator and the rotor. The rotating magnetic field cuts the rotor windings to generate induced electromotive force and current in the rotor circuit. The current in the rotor conductor forces the rotor to rotate under the effect of the rotating magnetic field. Below, let’s specifically analyze the generation of rotating magnetic field, its direction and speed as well as slip.

The starting methods of three phase induction motor generally are direct-on-line starting, reduced-voltage starting and soft starter.
Direct-on-line starting is the most basic and simplest in the motor starting. The method is characterized by less investment, simple equipment and small quantity. Although the starting time is short, the torque is smaller at starting and the current is large, which is suitable for starting small capacity motors.

Induction motor, also known as asynchronous motor, is a kind of AC electric motor. According to the different power phase, it can be divided into single-phase and three-phase. The main construction of induction motor is composed of two parts - stator and rotor. In addition, there are end bells, bearings, motor frame and other components. The following will give more details about the structure of three-phase induction motor or asynchronous motor.