In an ac motor two components of energy are present. One component is the real power which is converted from electrical into mechanical energy and into heat in the form of motor losses. The second, reactive energy, is stored in the inductive elements of the machine. If a motor, or any ac circuit for that matter, has no capacitive or inductive elements, then all of the energy is expended as real power, but if either capacitance, inductance, or both are present, then some reactive energy will also be present. Electric motors contain inductive elements and, therefore, reactive energy is a consideration in selecting and applying motors in an energy-efficient manner.
KeywordsPower Factor Induction Motor Reactive Energy Real Power Current Waveform
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- 1.NEMA Standards Publication No. MG2, “Safety Standard for Construction and Guide for Selection, Installation and Use of Electric Motors and Generators.” Washington, D.C.: National Electrical Manufacturers Association, 1989.Google Scholar
- 2.ANSI/NFPA 70, National Electrical Code. Boston, Mass.: National Fire Protection Association, 1981.Google Scholar
- 3.Wagner, C.F. Self-excitation of induction motors, AIEE Transactions, Vol. 58, 1939.Google Scholar
- 4.DeSieno, C.F., and Beaudoin, B.J. A guide to the application of capacitors without induction motor self-excitation, IEEE Transactions, Power Apparatus and Systems, Vol. 84, 1965.Google Scholar
- 5.Hehre, F.W., and Harness, G.T. Electrical Circuits and Machinery. New York: John Wiley & Sons, Inc., 1944.Google Scholar
- 6.Barkle, J.E., and Ferguson, R.W. Induction generator theory and application, AIEE Transactions, Power Apparatus and Systems, Vol. 73, 1954.Google Scholar
- 7.Tang, K.Y. Alternating Current Circuits. Scranton, Pa: International Textbook Co., 1940.Google Scholar