The elements of electrical engineering Volume 2; a text book for technical schools and colleges - Softcover
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 Excerpt: ...by (j-)2 we have the primary equivalent values, namely, 250 ohms (= r) and 200 ohms (= x), so that the primary current flows, as it were, through a circuit of which the resistance is 150 ohms + 250 ohms and of which the reactance is 100 ohms + 200 ohms. That is, the impedance of this equivalent simple circuit is 1/(400)2 + (300)3 = 500 ohms, so that the current is 2,000 volts-j-500 ohms or 4 amperes. Taking this current as the reference axis, the components of the supply voltage are 4 amperes x 400 ohms = 1,600 volts parallel to the current and 4 amperes x 300 ohms = 1,200 volts perpendicular to the current; the components of E' are 4 amperes X 250 ohms = 1,000 volts parallel to the current and 4 amperes x 200 ohms = 800 volts perpendicular to the current; the components of E" are Jff x 1,000 volts and x 800 volts parallel to and perpendicular to the current respectively; and the value of /" is of course 40 amperes. The student should represent these details in a clock diagram. 101. Relation between core flux and primary voltage.--The electromotive force in abvolts induced in each turn of wire of the primary coil of a transformer is at each instant equal to the rate of change of the core flux f, so that the total induced electromotive force in abvolts is equal to N', djdt, and this induced electromotive force is equal and opposite to the primary voltage e' at each instant (resistance of primary coil negligibly small), therefore where e' is expressed in abvolts. Example of core flux for a particular non-harmonic electromotive force.--The relation between core flux and primary voltage is simplest for the case in which the electromotive force curve is rectangular like the full-line curve in Fig. 176. Suppose, for %g second Fig. 176. example, that a 5...
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