. The influence of varying reactance upon the short circuit phenomena in alternators. gfor a moment the formula for the short-circuit current, asgiven by Bra Gray in his thesis, which takes the form, It is clear that the value of the current depends upon the term X, which is the reactance of the armature of the alternator. It is usual to assume the value of 1 to be constant, irrespective of what angle on the wave the short-circuit occurs. Jiut this assumption is not correct since the reactance of the armature varies v/ith the relative position of the armature and the field poles. Just w
. The influence of varying reactance upon the short circuit phenomena in alternators. gfor a moment the formula for the short-circuit current, asgiven by Bra Gray in his thesis, which takes the form, It is clear that the value of the current depends upon the term X, which is the reactance of the armature of the alternator. It is usual to assume the value of 1 to be constant, irrespective of what angle on the wave the short-circuit occurs. Jiut this assumption is not correct since the reactance of the armature varies v/ith the relative position of the armature and the field poles. Just what causes this variation in reactance can be seenfrom i(,igs. III. and IV., which represent sections of thearmature and field poles. ./hen a conductor is facing a pole,the reluctance of the magnetic path for the flux produced by thecurrent in the conductor is low, the path being practicallyall iron, and the flux reaches a maximum value, causing maximumself-inductance. V/hen the conductor has passed to a oosition 6 between the polos, however, the magnetic circuit being practically. of air, the reluctance is great and the flux is small causing alow inductance. Hence the inductance is a pulsating one, reach-ing a maximum when the conductor is opposite to a pole, anddecreasing to a minimum when the conductor is oetween two poles. Due to the fact,, that the armature reactance pulsates, itwould seem more logical to obtain the values of reactance fordifferent points on the wave, and use these actual valuesin calculating the magnitude of the current produced when thearmature is short-circuited at any known point on the ; rather than using an average value of reactance or thesynchronous reactance, as in the methods commonly emoloyed. To ootam the relative accuracy between the values of snort-circuit current, obtained by using either the average value ofreactance or the actual value of reactance, and experimentaldata, the calculations and tests recorded in this thesis w
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttheses, bookyear1913
