A concept, Three-phase asynchronous motor speed is classified, it is determined by the "pole" of the motor. The number of three-phase asynchronous motor "" is to specify the number of magnetic poles. The connection of the stator winding in a different way, can form the different number of stator magnetic field. Select the pole of the motor is needed by the load speed to determine, the number of motor directly affects the speed of the motor, the current of the motor only has something to do with the voltage and power of the motor. Motor speed = 60 x frequency motor/motor logarithmic Second, the classification of The number of 1, reflect the synchronous speed of the motor 2 pole synchronous speed was 3000 r/min, 4 pole synchronous speed was 1500 r/min, 6 pole synchronous speed was 1000 r/min, eight pole synchronous speed was 750 r/min. Winding the way go to form a loop, namely pole logarithm, come in pairs, extremely is the meaning of magnetic pole, the winding magnetic field when an electric current, there will be a pole. Each group of three-phase ac motor coil produces N and S poles, each motor each phase contains the number of poles is very few. Due to the magnetic poles are paired, so the motor with 2, 4, 6, 8... Extremely. 2, the frequency of the three-phase ac motor is 50 hz, the synthesis of the synchronous speed of the magnetic field of 50 r/s, which is 3000 r/min. If the rotating magnetic field of the motor is not just a pair of magnetic poles, further analysis can also get synchronous speed the relationship between n and logarithmic magnetic poles p: n = 60 f/p.f for frequency, unit for Hz. N units for r/min. Ns and the frequency of the alternating current (ac) (f), magnetic poles of the motor has strict relationship between log (P) ns = f/P. In China, power frequency 50 hz, so the diode motor synchronous speed is 3000 RPM, quadrupole motor synchronous speed is 1500 RPM, and so on. The speed of the rotor asynchronous motor is always less than or more than the speed, the rotating magnetic field induction in the name of the resulting. The difference between the rotational speed and rotating magnetic field of asynchronous motor rotor (called slip) usually within 10%. Therefore, the speed of the ac motor (either synchronous or asynchronous) are the restriction of the power frequency. Ac motor speed control, therefore, is hard, the best way is to change the power frequency, whereas in the past to change the power frequency is more complex. So before the 70 s, the speed required, multi-purpose dc motor. With the development of power electronic technology, the ac motor frequency control of motor speed technology has started to get practical. 3, the number of ac three-phase asynchronous motor for the total number of coil assembly is divided by three. Third, recognition methods 1, see speed 1430 r/min actual synchronous speed is 1500 RPM, the rotating speed formula: speed = time (60 seconds) x frequency (50 hz) divided by the logarithmic a magnetic poles of two pole, which can calculate the present 1500 = 3000 two poles of 4 pole motor. 2, see model was more direct: For example motor model is Y132M - 4 Y - three-phase asynchronous motor, three-phase asynchronous motor of the product name
