Fundamentals of Electric Motor Drives
Electric machines are an essential part of industry. They provide the necessary mechanical-to-electrical or electrical-to-mechanical conversion. In the United States, more than 50% of the electric...
View ArticleNEMA ENERGY-EFFICIENT MOTOR STANDARDS (Electric Motor)
2.7 In 1990, based on the experience gained by the electric motor manufacturers in producing energy-efficient polyphase induction motors and interest by industry, NEMA adopted a suggested standard for...
View ArticleMOTOR EFFICIENCY LABELING (Electric Motor)
2.6 Coincident with the NEMA test program, it was determined that a more consistent and meaningful method of expressing electric motor efficiency was necessary. The method should recognize that motors,...
View ArticleEFFICIENCY DETERMINATION (Electric Motor)
2.5 Efficiency is defined as the ratio of the output power to the input power to the motor expressed in percent; thus, TABLE 2.4b Full-Load Nominal Efficiencies of Three-Phase Four-Pole...
View ArticleWHAT IS AN ENERGY-EFFICIENT MOTOR? (Electric Motor)
2.4 Until recently, there was no single definition of an energy-efficient motor. Similarly, there were no efficiency standards for standard NEMA design B polyphase induction motors. As discussed...
View ArticleWHAT IS EFFICIENCY? (Electric Motor)
2.3 Electric motor efficiency is the measure of the ability of an electric motor to convert electrical energy to mechanical energy; i.e., kilowatts of electric power are supplied to the motor at its...
View ArticleWHY MORE EFFICIENT MOTORS? (Electric Motor)
2.2 The escalation in the cost of electric power that began in 1972 made it increasingly expensive to use inefficient electric motors. From 1972 through 1979, electric power rates increased at an...
View ArticleEnergy-Efficient Motors (Electric Motor)
2.1 STANDARD MOTOR EFFICIENCY During the period from 1960 to 1975, electric motors, particularly those in the 1- to 250-hp range, were designed for minimum first cost. The amount of active material,...
View ArticleSINGLE-PHASE INDUCTION MOTORS (Electric Motor)
1.2 There are many types of single-phase electric motors. In this section, the discussion will be limited to those types most common to integral-horsepower motor ratings of 1 hp and higher. In...
View ArticleInduction Motor Characteristics (Electric Motor)
1.1 THREE-PHASE INDUCTION MOTORS In the integral horsepower sizes, i.e., above 1 hp, three-phase induction motors of various types drive more industrial equipment than any other means. The most common...
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