Browsing by Subject "motor"
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Item Application of motor capacitors to improve facility power usage in the industrial setting(Texas A&M University, 2006-10-30) Hillhouse, William JeffreyAs deregulation of the electric power system in the United States unfolds, many customers are experiencing changes in their billing rate structure. Some face the addition of power factor penalty tariffs, and seek ways to minimize the added burden. The installation of entrance capacitor banks is the common response, but fails to take complete advantage of capacitor abilities. Other project designs exist that can harness these advantages to the full benefit of the customer. This work will show that distributing shunt capacitors in parallel with induction motors will elevate power factor and voltage, and also decrease ohmic losses in the wiring and protection devices that supply the motor. This reduction often produces a better overall economic solution due to energy savings. The distribution of capacitors at induction motors reduces the reactive current in the branch of the distribution system that supplies them. A reduction in the total current flowing to the motor along the distribution system results in smaller losses throughout the system. As losses diminish, the total real power drawn through the distribution system is lessened, and electric bills are reduced. This alternative to entrance capacitor banks is not as commonly implemented. A misconception that the resistance in facility distribution systems is relatively low has discouraged distributed motor capacitor installation for overall facility power factor correction, in favor of entrance capacitor banks. We will show that the resistance in the distribution system is higher than typically thought, that motor capacitors can exploit this fact, and can often economically outperform entrance capacitor banks which are terminated at the point of incoming utility power. Motor capacitors are not a new technology. They are commercially available off the shelf technology, suitable for power factor correction for induction motors. Distributed capacitors can be utilized for all significantly sized induction motors in a facility. The elevation in power factor and voltage, reduction in reactive current and real power are calculated, and trends are observed. The matter is considered from both the standpoint of engineering and economics to provide an integrated study.Item Reduction of Shaft Voltages and Bearing Currents in Five-Phase Induction Motor(2012-07-16) Hussain, HussainInduction motors are commonly used in numerous industrial applications. To maintain a reliable operation of the motor, it is important to identify the potential faults that may cause the motor to fail. Bearing failures are one of the main causes of motor breakdown. The causes of bearing damage have been studied in detail for a long time. In some cases, bearing failed due to the current passing through them. In this thesis, bearing currents in an inverter driven five-phase induction motor are studied and a new solution is proposed. First, theory of shaft voltage and bearing current are presented. The causes are identified and current solutions are discussed. Then, new switching patterns are proposed for the five-phase induction motor. The new schemes apply a modified algorithm for the space vector pulse-width-modulation (SVPWM). The system is simulated and the results of the new switching patterns are compared with the conventional switching pattern. Finally, the new schemes are experimentally tested using a digital signal processor (DSP) to drive the five-phase IGBT inverter. The experimental results verified that the new switching pattern could reduce shaft voltages and bearing current without affecting the performance.