DESIGN AND IMPLEMENTATION OF A SOFT START TO STARTASINGLEPHASE INDUCTION MOTOR

The use of induction motor in various facets of engineering, manufacturing and the production sector to power various equipment have gained stability and thereby creating huge starting current which in turn contributes to the unbalanced loading of network giving rise to high energy and economic loss. This research work, therefore, seeks to reduce the starting current of the connected single-phase induction motor. A smooth and soft start is employed in a single-phase induction motor to eliminate the surge in current and electromagnetic torque during starting. The surge in current and torque are eliminated using soft starter at the time of starting. The soft starter also eliminates the unwanted effect in electric cables and the distribution network. This project work provides an in-depth description of the sentimental and smooth start to an induction motor. The smooth start of the motor is predicted by the firing angle of the TRIAC circuit. The firing angle is delayed during starting and the delay angle reduces as the motor picks up to speed. This proposed technique provided reduced voltage at the starting and the rated voltage when themotor is up to speed. By using soft starter, the performance and efficiency of the induction motor is improved and it also improves the load torque characteristics. This project consists of 6anti-parallel SCR connected in each series with an induction motor to the main supply, where into each phase. When starting the firing angle is heavily delayed by receiving delayed triggering pulses. The supplied voltage is gradually increased, and the torque also in same manner. By this process the inrush current is drastically reduced, making the motor start smoothly. The induction motor of0.56KW, frequency of 50Hz, maximum voltage 230V, receives little or no surge using the soft starter device. The start up ramp is about 4s to 7s, depending on the power of the induction motor. The firing angle is gradually decreased from 80˚ by interval of 20˚ until 0˚ max of the full half