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Authors
Affiliations
1 New Horizon College of Engineering, IN
2 EEE, NHCE, Bangalore, IN
Source
International Journal of Engineering Research, Vol 5, No SP 5 (2016), Pagination: 1100-1104
Abstract
This paper is describes the soft and smooth start to a 3 phase induction motor. The three phase induction motor during the initial starting condition draws up much higher current than its capacity and the motor instantly reaches the full speed. This results in a mechanical jerk and high electrical stress on the windings of the motor. Sometimes the windings may get burnt. The prototype have been developed to give a soft start to the induction motor based on the SCR firing triggered by heavily delayed firing angle during starting and then gradually reducing the delay till it reaches zero voltage triggering. This results in low voltage during start and then gradually to full voltage. Thus the motor starts slowly and then slowly picks up to full speed. The working prototype consists of a six anti-parallel SCRs, two for each phase, the output of which is connected to a set of lamps representing the coils of a 3 phase induction motor, capacitors, comparators ,opto-isolators to trigger the SCRs etc .This can be enhanced by using IGBTs in place of SCRs with PWM control to reduce harmonic distortions often encountered in SCR triggering mechanism for future scope. The implementation of hardware model has been discussed in this paper.
Keywords
SCR Triggering, Firing Angle Delay, Optoisolators, Optocouplers, Zero Voltage Triggering, Motor Current Control.
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