31-03-2016, 01:41 PM
06-04-2016, 02:14 PM
energy efficient motors seminar topic pdf
Energy efficient motors use less electricity, run cooler, and often last longer than NEMA (National Electrical Manufacturers Association) B 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 mechanical power delivered by the motor (output) to the electrical power supplied to the motor (input).
Efficiency = (Mechanical Power Output / Electrical Power Input) x 100%
Thus, a motor that is 85 percent efficient converts 85 percent of the electrical energy input into mechanical energy. The remaining 15 percent of the electrical energy is dissipated as heat, evidenced by a rise in motor temperature. Energy efficient electric motors utilize improved motor design and high quality materials to reduce motor losses, therefore improving motor efficiency. The improved design results in less heat dissipation and reduced noise output.
Most electric motors manufactured prior to 1975 were designed and constructed to meet minimum performance levels as a trade-off for a low purchase price. Efficiency was maintained only at levels high enough to meet the temperature rise restrictions of the particular motor. In 1977, the (NEMA) recommended a procedure for labeling standard three-phase motors with an average nominal efficiency. These efficiencies represent an industry average for a large number of motors of the same design. Table 1 compares the current Standard full load nominal efficiencies for standard and energy efficient motors of various sizes. Note that these efficiencies are averages for three-phase Design B motors. (Design B motors account for 90 percent of all general purpose induction motors. See NEMA Specifications Publication MG-1-1.16 for classifications of induction motors.) Motors of other types (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 speed-torque characteristics.
Energy efficient motors use less electricity, run cooler, and often last longer than NEMA (National Electrical Manufacturers Association) B 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 mechanical power delivered by the motor (output) to the electrical power supplied to the motor (input).
Efficiency = (Mechanical Power Output / Electrical Power Input) x 100%
Thus, a motor that is 85 percent efficient converts 85 percent of the electrical energy input into mechanical energy. The remaining 15 percent of the electrical energy is dissipated as heat, evidenced by a rise in motor temperature. Energy efficient electric motors utilize improved motor design and high quality materials to reduce motor losses, therefore improving motor efficiency. The improved design results in less heat dissipation and reduced noise output.
Most electric motors manufactured prior to 1975 were designed and constructed to meet minimum performance levels as a trade-off for a low purchase price. Efficiency was maintained only at levels high enough to meet the temperature rise restrictions of the particular motor. In 1977, the (NEMA) recommended a procedure for labeling standard three-phase motors with an average nominal efficiency. These efficiencies represent an industry average for a large number of motors of the same design. Table 1 compares the current Standard full load nominal efficiencies for standard and energy efficient motors of various sizes. Note that these efficiencies are averages for three-phase Design B motors. (Design B motors account for 90 percent of all general purpose induction motors. See NEMA Specifications Publication MG-1-1.16 for classifications of induction motors.) Motors of other types (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 speed-torque characteristics.