. Theory and calculation of alternating current phenomena . r. CHAPTER V SYMBOLIC METHOD 25. The graphical method of representing alternating-currentphenomena affords the best means for deriving a clear insightinto the mutual relation of the different alternating sine wavesentering into the problem. For numerical calculation, however,the graphical method is generally not well suited, owing to thewidely different magnitudes of the alternating sine waves rep-resented in the same diagram, which make an exact diagram-matic determination impossible. For instance, in the trans-former diagrams (c/. F
. Theory and calculation of alternating current phenomena . r. CHAPTER V SYMBOLIC METHOD 25. The graphical method of representing alternating-currentphenomena affords the best means for deriving a clear insightinto the mutual relation of the different alternating sine wavesentering into the problem. For numerical calculation, however,the graphical method is generally not well suited, owing to thewidely different magnitudes of the alternating sine waves rep-resented in the same diagram, which make an exact diagram-matic determination impossible. For instance, in the trans-former diagrams (c/. Figs. 18-20), the different magnitudes havenumerical values in practice somewhat like the following: Ei= 100 volts, and 7i = 75 amp. For a non-inductive second-ary load, as of incandescent lamps, the only reactance of thesecondaiy circuit thus is that of the secondary coil, or Xi = , giving a lag of ^i = °. We have also, rii = 30 turns. rio = 300 turns. Fi = 2250 ampere-turns. F =100 ampere-turns. Er = 10 volts. E:, = 60 volts. Ei = 1000 Fig. 21.—Vector diagram of transformer. The corresponding diagram is shown in Fig. 21. Obviously,no exact numerical values can be taken from a parallelogramas flat as OFiFFo, and from the combination of vectors of therelative magnitudes 1 :6 :100. Hence the importance of the graphical method consists not 30 SYMBOLIC METHOD 31 so much in its usefulness for practical calculation as to aid inthe simple understanding of the phenomena involved. 26. Sometimes we can calculate the numerical values trigo-nometrically by means of the diagram. Usually, however, thisbecomes too complicated, as will be seen by trying to calculate,from the above transformer diagram, the ratio of primary is given by the equation
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