There are several ways to control the speed of an induction motor and the best way would be to have a variable frequency AC drive. The asynchronous motor represents the most important and simple case in the area of poly phase machines and it is the most widespread for industrial applications as food, chemical, metallurgical industries, paper factories or water treatment and extractive systems. The speed control can be achieved also through a manual control of a potentiometer with or without acceleration and deceleration ramps. The speed will be a little slower than the applied frequency but fairly close and to obtain an exact speed a feedback loop is provided with the bench to measure the rotating frequency and to adjust the variable frequency AC drive maintaining that speed as the motor speed will decrease a bit due to an electromagnetic brake acting as a load. The variable frequency AC drive can be programmed from keyboard with on screen guide.
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