Award Date


Degree Type


Degree Name

Master of Science (MS)


Electrical and Computer Engineering

Number of Pages



Induction motors are known to cause undesirable voltage dip because of high inrush current during starting, especially when fed from weak AC systems. For this reason, large motors are often started with reduced voltage. This thesis proposes full-voltage motor starting with shunt capacitors. Two types of capacitors are used: power factor correction capacitor and start capacitor. The start capacitor is determined to maximize the input impedance during starting in order to reduce the initial inrush current. The analysis shows that shunt capacitors improve the voltage dip and the motor acceleration significantly but introduce some level of waveform distortion during each starting period. The start capacitor is found to be very effective in voltage control, but additional components such as damping resistor must be added to effectively reduce the waveform distortion. A centrifugal switch is used to replace the start capacitor and damping resistor by a power factor correction capacitor as the motor reaches a predetermined speed. The feasibility of the proposed scheme is proven through a mathematical model and associated computer simulations. The simulation results are verified by laboratory experiments.


Alternate; Approach; Capacitors; Control; Dip; Motor; Shunt; Starting; Voltage

Controlled Subject

Electrical engineering

File Format


File Size

1003.52 KB

Degree Grantor

University of Nevada, Las Vegas




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