Time filter

Source Type

Ferreira F.J.T.E.,University of Coimbra | Cisneros-Gonzalez M.,Technological Institute of the Valle del Guadiana | de Almeida A.T.,University of Coimbra
Energy Efficiency | Year: 2015

In industry, due to conservative system design, safety factors associated with uncertainty in the load requirements, discrete availability of commercial rated power, and/or load power variation, most three-phase squirrel-cage induction motors are oversized. Besides the extra capital investment, the oversizing of direct-on-line fixed-speed induction motors can lead to a significant efficiency and power factor reduction. However, the part-load efficiency of oversized motors can still be higher than the full-load efficiency of well-sized smaller motors because, in general, the nominal efficiency increases with the rated power. In this paper, an analysis of potential benefits and drawbacks of motor oversizing is carried out. On the basis of the catalogue technical data provided by one of the largest motor manufacturers for IE1-, IE2-, IE3-, and IE4-class four-pole induction motors, the main results of a simulation-based study on the oversizing energy efficiency and cost-effectiveness are presented. A method to estimate the motor efficiency and power factor for any load level using commercial catalogue data is proposed and applied. Some technical issues associated with motor oversizing are also briefly addressed. It is shown that, if the additional reactive energy consumption due to poorer power factor and the slight speed increase are ignored, for IE1-, IE2- and, to a much less extent, IE3-class motors, oversizing can be cost effective for many motor rated powers, resulting in a higher average efficiency and a lower motor lifecycle cost, as well as in an extended motor lifespan. For most IE3- and IE4-class motors, the oversizing is not cost effective because of the lower nominal efficiency gain when moving to a higher oversized rated power. Additionally, the oversizing impact on the motor energy consumption strongly depends on the load profile of the application. When an old motor fails, it will probably be an IE0- or IE1-class equivalent motor, and this situation provides a golden opportunity for replacing the old motor with a properly sized IE3- or IE4-class motor, which offers significantly higher efficiency for a wide range of loads. © 2015 Springer Science+Business Media Dordrecht

de la Rosa Reyna X.F.,National Polytechnic Institute of Mexico | Montoya H.M.,Texas A&M University | Castrellon V.V.,Technological Institute of the Valle del Guadiana | Rincon A.M.S.,National Polytechnic Institute of Mexico | And 2 more authors.
Genetics and Molecular Research | Year: 2010

The IGF1 gene (insulin-like growth factor 1) is a candidate gene for marker-assisted selection strategies. A single nucleotide polymorphism in the promoter region (IGF1/SnaBI) has been reported to be associated with production traits in several cattle breeds. Here, we report its allelic frequencies in Charolais and Beefmaster breeds; we confirm its association with three growth traits: weaning weight, weaning weight adjusted to 210 days and preweaning weight gain in the Charolais breed. In addition, we designed a strategy to search these breeds for new polymorphisms in four coding regions of the gene. A C/A transversion was detected in intron 4, but it was not associated with the growth traits. A single nucleotide polymorphism (IGF1/SnaBI) is proposed as a selection marker for Mexican Charolais cattle; validation of its association with weaning weight, weaning weight adjusted to 210 days and preweaning weight gain, could complement the genetic evaluations of this breed through marker-assisted management strategies. © FUNPEC-RP.

Cisneros-Gonzalez M.,Technological Institute of the Valle del Guadiana | Arjona M.A.,Technological Institute of La Laguna
Proceedings - 2012 20th International Conference on Electrical Machines, ICEM 2012 | Year: 2012

This paper presents an educational tool for illustrating the measured power in induction motors. This tool is integrated by hardware and software elements. The software uses a virtual instrument which is developed on the LabVIEW programming language. This instrument helps to perform online measurements of the quantities: power, apparent power, reactive power and power factor, as well the energy usage. A phasor diagram shows the three-phase current and voltage quantities; at the same time, a spectral analysis is also computed. The hardware uses a three-phase power amplifier and a set of Hall-effect sensors which are easily found on the market. Measurements are taken when the induction motor is in at standstill and under loaded conditions. The tool was tested in a 0.5 HP, 220V and 60 Hz induction motor. © 2012 IEEE.

Cisneros-Gonzalez M.,Technological Institute of the Valle del Guadiana | Hernandez C.,Technological Institute of La Laguna | Morales-Caporal R.,Apizaco Institute of Technology | Bonilla-Huerta E.,Apizaco Institute of Technology | Arjona M.A.,Technological Institute of La Laguna
IEEE Transactions on Energy Conversion | Year: 2013

This paper presents the application of the time-domain chirp signal excitation to obtain the dq axis parameters of a synchronous machine model. The latest advances on computation tools have allowed the research of existing and novel experimental procedures for the parameter estimation of synchronous-generator models. Hence, different experimental methodologies to reduce the amount of testing time and to obtain more accurate model parameters have been proposed. The chirp is a linear swept-frequency sinusoidal signal that allows exciting the generator over a specified frequency bandwidth. This excitation is applied to the dq axis positions while the generator is at standstill. The estimation of the fundamental parameters is made by using a hybrid optimization algorithm composed by a genetic and a quasi-Newton algorithm. The proposed test has the advantage of requiring a low testing time. The set of estimated parameters was validated using test data of a sudden three-phase short-circuit fault. A 7 kVA, 220 V, 60 Hz, 1800 r/min, four salient-pole synchronous machine was used to evaluate the proposed estimation approach. © 1986-2012 IEEE.

Arjona M.A.,Technological Institute of La Laguna | Hernandez C.,Technological Institute of La Laguna | Cisneros-Gonzalez M.,Technological Institute of the Valle del Guadiana | Escarela-Perez R.,Metropolitan Autonomous University
International Journal of Electrical Power and Energy Systems | Year: 2012

The parameter estimation of a synchronous generator using the dc-step voltage is presented in this paper. The dc-step voltage is a standstill experiment needed to generate the required data to estimate the fundamental parameters of the d-q axis equivalent circuits. A hybrid Genetic Algorithm is used in the estimation process. A model with one damper winding along each axis is adopted. The unequal mutual effect of field and d-axis damper windings is taken into account. To check the validity of the estimated parameters, a sudden three-phase short-circuit test is applied at the generator terminals. The measured data are compared against the simulation response of the machine model using the parameters estimated from the dc-step voltage. Furthermore, the description of the developed experimental setups for both standstill and online tests is presented. A synchronous generator of 7 kVA, 220 V, 1800 rpm, 60 Hz was used in the study. © 2011 Elsevier Ltd. All rights reserved.

Discover hidden collaborations