When buying motor universal, we need to know its model and how the ac motor speed regulation?
Rated speed n=60f/ P (1-s)= synchronous speed N1(1-s) F power frequency P motor pole logarithm S slip
1. Use frequency converter to change power frequency speed regulation, with wide range of speed regulation, good stability and smoothness, and hard mechanical characteristics.That is, with the rated load, the speed drops less.It belongs to stepless speed regulation.Suitable for most three-phase squirrel-cage induction motors.
2. Change the magnetic pole logarithmic speed regulation, which belongs to the stage speed regulation, speed smoothness difference, generally used for metal cutting machine tools.3. Change slip speed.
(1) Rotor loop series resistance: used for AC wound asynchronous motors.Small speed range, resistance to consume power, low motor efficiency.Generally used in cranes.
(2) Change the power voltage speed regulation, speed range is small, torque with the voltage drop greatly decreased, three-phase motor is generally not used.Used for single-phase motor speed regulation, such as fan.
(3) cascade speed regulation, the essence is that the rotor introduced additional electromotive force, change its size to speed regulation.Also only used for winding motor, but the efficiency is improved.
(4) Electromagnetic speed regulation.For slip motor only.By changing the current of the excitation coil, the speed regulation is smooth, the mechanism is simple, but the control power is small.Do not run at low speed for a long time.