Identifier: cyclopediaofappl04amer (find matches)
Title: Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc.
Year: 1916 (1910s)
Authors: American Technical Society
Subjects: Electric engineering
Publisher: Chicago : American Technical Society
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Northeastern University, Snell Library

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ng power to the fly wheel of the drivingengine or turbine. When the inductance of the receiving circuit is very large, theelectromotive force and current curves are related as shown in Fig.IS; the instantaneous power ei passes through approximately similarsets of positive and negative values, as shown by the light-dotted curve; and the average power is approx-^ imately zero. This case would be very ^ closely exemplified by an alternator con-nected to a transformer whose secondarywas open-circuited, that is, supplying noy (Y current. y\ Harmonic Electromotive Forces and ^ ^ Currents. A line OP, Fig. 19, revolves, at a uniform rate, / revolutions per secondabout a point 0, in the direction of thearrow gh. Since the length of OF is fixed,the path or locus of the point P will be acircle about 0 as a center. Consider theFig. 19. Diagram of Harmonic projcction 06 of this Totatiug liuc upon the fixed line AB, this projection beingconsidered positive when above 0 and negative when below 0. 26
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w „ hS aO^ 2 go g «w H ALTERNATING-CURRENT MACHINERY 17 A harmonic electromotive force (or current) is an electromotiveforce (or current) which is at each instant proportional to the line Oh. The line Oh represents at each instant the actual value e of theharmonic electromotive force to a definite scale, and the length ofthe line OP, which is the maximum length of Oh, represents themaximum value E of the harmonic electromotive force to the samescale. The line Oh passes through a complete cycle of values duringone revolution of OP, and so also does the harmonic electromotiveforce e. Therefore, the revolutions per second / of the line OP isthe frequency of the harmonic electromotive force e. The rotatingHues E and I, Fig. 20, of which the projections on a fixed line (notshown in the figure) represent the actual instantaneous values eand i of a harmonic electromotive force and a harmonic current,are said to represent the harmonic electromotive force and cur-rent, respectively. Of cour

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