An electric motor is rated at 10 horsepower (HP) and costs $800. Its full-load efficiency is specified to be 85%. A newly designed, high-efficiency motor of the same size has an efficiency of 90%, but costs $1,200. It is estimated that the motors will operate at a rated 10-HP output for 1,500 hours a year, and the cost of energy will be $0.07 per kilowatt-hour. Each motor is expected to have a 15-year life. At the end of 15 years, the first motor will have a salvage value of $50, and the second motor will have a salvage value of $100. Consider the MARR to be 8%. (Note: l HP= 0.7457kW.)(a) Determine which motor should be installed based on the PW criterion.(b) What if the motors operated 2,500 hours a year instead of 1,500 hours ayear? Would the motor selected in (a) still be the choice?
An electric motor is rated at 10 horsepower (HP) and costs $800. Its full-load efficiency is specified to be 85%. A newly designed, high-efficiency motor of the same size has an efficiency of 90%, but costs $1,200. It is estimated that the motors will operate at a rated 10-HP output for 1,500 hours a year, and the cost of energy will be $0.07 per kilowatt-hour. Each motor is expected to have a 15-year life. At the end of 15 years, the first motor will have a salvage value of $50, and the second motor will have a salvage value of $100. Consider the MARR to be 8%. (Note: l HP= 0.7457kW.)
(a) Determine which motor should be installed based on the PW criterion.
(b) What if the motors operated 2,500 hours a year instead of 1,500 hours a
year? Would the motor selected in (a) still be the choice?
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