The dual speed motor belongs to the pole changing speed regulation of asynchronous motor. It changes the number of the magnetic field poles of the stator by changing the connection method of the stator winding, thereby changing the speed of the motor.
According to the n=60f/p formula; asynchronous motor synchronous speed and number of pole pairs is inversely proportional to the number of pole pairs double half synchronous speed n down to the original speed, motor rated speed n will decline to approximately half, so change the poles of the motor speed can be changed. This method of speed regulation is level, can not smooth speed regulation, and is only applicable to the squirrel cage motor.
The two speed motor is mainly used in coal, petroleum, natural gas, petrochemical and chemical industry. In addition, it is also widely used in textile, metallurgy, city gas, transportation, grain and oil processing, paper making, medicine and other departments. As the main power equipment, the dual speed motor is usually used for driving pumps, fans, compressors and other transmission machines.
With the development of science and technology and production, the place of explosion danger is also increasing. For example, the production of edible oil is used in traditional pressing process, after 1970s, China began to introduce foreign advanced technology of oil extraction, but this process should be used in chemical solvents containing ethane, ethane is flammable and explosive substances; oil extraction plant therefore became explosive dangerous places, need to use double speed motor and other explosion-proof electrical products. In addition, in recent years, the rapid development of China's highways, a large number of fuel gas stations appear, and also provide a new market for the double speed motor.