According to statistics, the classification of AC motors can be done in the following two ways: By function AC motors are generally classified into alternators, AC motors, and synchronous cameras according to their functions. Due to the reversibility of the working state of the motor, the same motor can be used as both a generator and an electric motor. It is not very clear that the motor is divided into a generator and a motor. However, some motors mainly operate as generators, and some motors mainly operate as motors. By variety AC motors are divided into two categories: synchronous motors and asynchronous motors. The rotational speed ns of the synchronous motor rotor is the same as the rotational speed of the rotating magnetic field, and is called synchronous rotational speed. There is a strict relationship between ns and the frequency of the connected alternating current (f) and the number of magnetic pole pairs (P) of the motor. Ns=60f/P In China, the power frequency is 50 Hz, so the synchronous speed of the one-pole motor in the three-phase AC motor is 3000 rpm, and the synchronous speed of the two-pole motor in the three-phase AC motor is 1500 rpm, and so on. The speed of the asynchronous motor rotor is always lower or higher than the rotational speed of its rotating magnetic field, and the name of the asynchronous is thus derived. The difference between the rotor speed of an asynchronous motor and the rotational magnetic field speed (called the slip) is usually within 10%. |