Abstract: AC motors are predominant in the field of industrial Drives. They are widely used because of their efficiency, less maintenance, construction. Speed control is a vital requirement of industries today. The parameter which takes the features of the induction motor away from the DC motor is its speed control. The speed control of AC Motors by conventional method of pole changing, voltage and frequency are very complicated and require more time and are less efficient or expensive techniques. So in industrial applications where variable speed is required, an easy and quick speed control method has to be employed. Here we are going to make use of 89C51 microcontrollers along with electronic circuitry to regulate the speed and retrieve the real time speed on the digital display screen. The speed measurement will be employed by means of infrared transmitter and receiver. Depending on rotation a pulse will be generated and measured by the microcontroller. This ensures quick speed regulation as per the requirement of the user the firing angle is changed to regulate the speed. This would give the use of real time data of running motor; this will prevent the operator from reaching the maximum speed. Thus overall technique will provide reliable and flexible control on the motor.

Keywords: At89C51, Triac, Single phase Induction Motor, LCD etc.