haii ,
i want a simple seminar report about 'energy efficient motor' . it includes its theory , graphs, picture etc related to the topic .
sincerely and immediately post a seminar report and appropriate slides .

my email adress:ashiqmuhammed1794[at]gmail.com

Energy efficient motors

Low-energy engines consume less electricity, run colder, and often last longer than NEMA B (National Electrical Manufacturers Association) motors of the same size.

To effectively evaluate the benefits of high efficiency electric motors, we must define "efficiency". For an electric motor, efficiency is the ratio of the mechanical power supplied by the motor (output) to the electrical power supplied to the motor (input).

Efficiency = (Mechanical Power Output / Power Input) x 100%

Therefore, an engine that is 85 percent efficient converts 85 percent of the input of electrical energy into mechanical energy. The remaining 15 percent of the electrical energy dissipates as heat, evidenced by an increase in engine temperature. Energy-efficient electric motors use improved engine design and high-quality materials to reduce engine losses, thereby improving engine efficiency. The improved design results in less heat dissipation and reduced noise output.

Most electric motors manufactured before 1975 were designed and built to meet minimum performance levels as a trade-off for a low purchase price. The efficiency was only maintained at levels high enough to meet the particular engine temperature rise restrictions. In 1977, the NEMA recommended a procedure for the labeling of standard three-phase motors with average rated efficiency. These efficiencies represent an industry average for a large number of engines of the same design. Table 1 compares the nominal standard full load efficiencies for standard and energy efficiency motors of various sizes. Note that these efficiencies are averages for 3-phase B design motors. (B-type motors account for 90 percent of all general-purpose induction motors.) Other types of motors (Design A, C or D) have slightly different efficiencies, while single-phase motors have substantially lower efficiencies. Energy-efficient motors are only marketed with NEMA B torque-speed characteristics.

Theory

Engine efficiency is a factor in a variety of mechanical and electrical imperfections within the engine. Resistance losses (I2R) in stator windings and in rotor bars can account for up to 15 percent loss of efficiency in three-phase motors. The losses of I 2 R in single phase fractional power motors can be as high as 30 percent. The magnetization losses in the stator and rotor cores cause a loss of efficiency of 1 percent to 7 percent. Bearing friction losses and inefficiency in cooling fans result in a 0.5 to 1.5 percent loss in engine efficiency. Friction and magnetization losses are independent of engine load and refer only to engine size and design. The remaining losses are called lost load losses. Severely underloaded motors have lower efficiencies because friction and vent and core losses remain constant and comprise an increasing percentage of total engine power consumption. The following figure shows the different components of engine losses depending on the engine load.

Building materials and the mechanical and electrical design of a motor dictate its final efficiency. Energy efficient motors use high quality materials and use an optimized design to achieve greater efficiencies. Large-diameter copper wire in the stator and more aluminum in the rotor reduce energy-efficient motor resistance losses. Improving the rotor configuration and optimizing the air gap between the rotor and the stator results in reduced losses in the lost load. An optimized cooling fan design provides ample engine cooling with minimal wind loss. Thinner and higher quality steel laminations in the rotor and stator core enable the energy efficient motor to operate with substantially lower magnetization losses. High quality bearings reduce friction losses.

Cost Savings Analysis
Building materials and the mechanical and electrical design of a motor dictate its final efficiency. Energy efficient motors use high quality materials and use an optimized design to achieve greater efficiencies. Large-diameter copper wire in the stator and more aluminum in the rotor reduce energy-efficient motor resistance losses. Improving the rotor configuration and optimizing the air gap between the rotor and the stator results in reduced losses in the lost load. An optimized cooling fan design provides ample engine cooling with minimal wind loss. Thinner and higher quality steel laminations in the rotor and stator core enable the energy efficient motor to operate with substantially lower magnetization losses. High quality bearings reduce friction losses.
Cost Savings Analysis
When considering energy efficiency engines, two factors will affect the recovery period: the cost of energy and the hours of operation per year. Where electricity is cheap or operating time is low, it may take several years for high efficiency motors installation savings to offset the difference in initial cost. On the other hand, where energy costs and operating hours per year are high, it may be possible to replace an existing standard efficiency engine with an energy efficiency engine and make a paycheck of less than one year.