Energy Savings on Single-Phase Induction Motors under Light Load Conditions by Fatima Bouzidi Dr. Yahia Baghzouz, Examination Committee Chair Professor o f Eleetrieal & Computer Engineering University o f Nevada, Las Vegas It is estimated that eleetrie motors consume approximately two-third o f all the electric energy generated in the United States. It is also a known fact that induction motors found in residential and commercial applications are often oversized and operate well below their rated capacity. Because the effieieney o f an eleetrie motor is reduced at lighter load, numerous studies have been conducted in the past to reduce motor losses under such load conditions by either lowering the supply voltage (and in some eases, supply fi'cquency) by means o f static power converters. But some articles reported eonflieting results in terms o f energy savings for different duty cycles. The objective o f this thesis is to determine the most efficient way to operate a number o f common single-phase induction motors when operating below their horsepower ratings. To accomplish this, the following steps are taken: A) Characterize the motors in terms o f their performance (at nominal voltage) and model parameters. B) Simulate the steady-state performance under lower voltage (by SCR control) and lower load.

/pdf/energy-savings-on-single-phase-induction-motors-under-light-1quh634b0c.pdf

Energy savings on single-phase induction motors under light load conditions

Power factor correction (PFC) is a technique of counteracting the undesirable effects of electric loads that create a power factor that is less than one. Power factor correction may be applied either by an electrical power transmission utility to improve the stability and efficiency of the transmission network or correction may be installed by individual electrical customers to reduce the costs charged to them by their electricity supplier. Many control methods for the Power Factor Correction (PFC) have been proposed. This work describes the design and development of a power factor corrector using PIC (Programmable Interface Controller) microcontroller chip. Measuring of power factor from load is achieved by using PIC Microcontroller-based developed algorithm to determine and trigger sufficient switching of capacitors in order to compensate demand of excessive reactive power locally, thus bringing power factor near to unity.

/pdf/design-and-implementation-of-microcontroller-based-o2la3769o0.pdf

Design and Implementation of Microcontroller-Based Controlling of Power Factor using Capacitor Banks with Load Monitoring

Various inductive loads used in all industries deals with the problem of power factor improvement. Capacitor bank connected in shunt helps in maintaining the power factor closer to unity. They improve the electrical supply quality and increase the efficiency of the system. Also the line losses are also reduced. Shunt capacitor banks are less costly and can be installed anywhere. This paper deals with shunt capacitor bank designing for power factor improvement considering overvoltages for substation installation. Keywords— Capacitor Bank, Overvoltage Consideration, Power Factor, Reactive Power

Capacitor Bank Designing for Power Factor Improvement

http://tudr.thapar.edu:8080/jspui/bitstream/10266/725/3/T725.pdf

Development of Power Factor Controller using PIC Microcontroller

In the current scenario, power factor has become an important concern in all industries. Poor power factor gives rise to many problems which result in financial loss of industries and also for the commercial users. The main concern of this work is to improve the usage of real power with respect to reactive power hence improving the power factor. Here we have used the technique of relay switching method with a capacitor so that any drop in power factor can be sensed by the controller and switch the capacitor as required. This will not only help to improve power factor but also demand of electricity supply on utility side will be reduced. The Significance of this work is to build an APFC (Automatic Power Factor Correction) Unit. The APFC appliance calculates the reactive power (KVAR) expended by a system’s load and compensates the lagging PF (power factor) utilizing capacitances from capacitor banks. Keyword: Potential Transformer, Amplifier (Op-Amp), Current Transformer, Two Microcontroller, Capacitors, Conductors, Relays, LCD 20x4 (Liquid Crystal Display).

http://journals.uobasrah.edu.iq/article_144339_9e84dee36f42d9395d4e8343fa88bf12.pdf

Automated Power Factor Correction for Smart Home

A technique for maintaining a synchronous motor at unity power factor (or minimum line current) from no-load to full-load conditions, assuring peak efficiency, is described. This concept stems from an adaptation of the Energy Saver Power Factor Controller for induction motors recently developed and patented by NASA Marshall Space Flight Center. The method constantly and automatically adjusts the dc field current of a 3-phase synchronous machine such that the ac line current will always be operating at the minimal point of the well known "V" curves. This is accomplished as the load varies over its full operating range.

D. Blackwell

Papers

Energy Saver Power Factor Controller for Synchronous Motors