File:An Oscillographic investigation of current and EMF- waves of telephone magneto generators (1907) (14569739450).jpg

Identifier: oscillographicin00morr (find matches)
Title: An Oscillographic investigation of current and EMF- waves of telephone magneto generators
Year: 1907 (1900s)
Authors: Morrison, Rudolph A Lurvey, David Reker, William
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Contributing Library: Paul V. Galvin Library, Illinois Institute of Technology
Digitizing Sponsor: CARLI: Consortium of Academic and Research Libraries in Illinois

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requency ^ may be represented by an expression of theform . where co^zrrj^^ a, a^a^ are the amplitudes and 0,,0-2..0^,t)xQphases* The frequency of the first term isj* and those of theother terms are 2/, 3jj. The first term is called the funda-mentaljV/hilft the others are called the first, second, etc.harmonics.The even hannonics are absent from the curvesrepresenting alternating currents and E.M.?s,so these mayberepresented b^^ the expressiona, •S/y7(c^t -0,) -A a^ Sft-7(2coe -&3) -f- C?^<^/rf (<^o<jt - &^)-f- - - figure # 13 shows the curve, A,compounded of thefundamental and the second harmonic» .In this case the phaseangle, e,is Zero, and A represents the current wave for a non-inductive load.The curve,R,obtained vdth the oscillograph,for non-inductive load aftd is more distorted than that shown inFigure #/5which is siy-mmetrical.The curve R is not s^Tmnetrical.Being steeper on one side and reading the maximum value before90 degrees. bOW0IH3-O0 N3nZJ.3IO 3N3ona
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Referring back to Pigure # 7 which is for non-inductive load,it is seen that the resultdijS magnetism OM is larger on oneside of the circle OMA ^han it is on the other,thus the E,M,3?,is greater on one side^,this accounts for the shape of thecurve R. In figure # 14 the phase angle has heen taken at a lagof forty degrees.The fundamental and harmonic are displacedas shown, and the curve B is compounded of the two.This curve is inte^ed to represent the current wave for aninductive load.In the oscillfltgraph curves B, B-^B^and B^which are for inductive loads;^^ is seen that the currentrises ver^- rapidly at first and then gradually decreases.Curve B figure # 14closely represents the true carves.Ifhowever the correct angle of lag,the correct nt^Toer of higherh.ajmonics,and the correct value for the ataplitude .weretaJcen a curve might he constructed which would more closelyreseml3le the true current wave.It is heyond the scope of thispaper to construct such a theoretical curve; it is inten

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