SOFT START

The use of induction motor in various facet of engineering manufacturing and production sector to power various equipment have gained stability and thereby creating huge starting current which in turn contribute to the unbalance 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 incurrent and electromagnetic torque during starting. The surge in current an torque are eliminated using soft starter at the time of starting. The soft starter also eliminates the unwanted effect in electric cables and distribution network. This project work provides an in depth description of 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 the motor 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 6 anti- parallel SCR connected in each series with an induction motor to the main supply, wherein two to each phase. During starting the firing angle is heavily delayed by receiving a 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 of 0.56KW, frequency of 50Hz, maximum voltage 230V, receives little or no surge using the soft 6 starter device. The startup 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 A.C voltage.