. Effect of wave form upon the iron losses in transformers . ind where ^ = 0. If, however, the emf. cross theaxis more than this number of times, it becomes necessary to discrimi-nate between the different values of <^ for which ^ = 0. This takesplace only in cases where there are secondary maxima in the fluxcurve, and it is of course the highest maximum which must belocated. For any half wave of emf. the number of crossings will bean odd number, and they are alternately in the same direction asthe fundamental wave and in the opposite direction. Those in theopposite direction represent mini
. Effect of wave form upon the iron losses in transformers . ind where ^ = 0. If, however, the emf. cross theaxis more than this number of times, it becomes necessary to discrimi-nate between the different values of <^ for which ^ = 0. This takesplace only in cases where there are secondary maxima in the fluxcurve, and it is of course the highest maximum which must belocated. For any half wave of emf. the number of crossings will bean odd number, and they are alternately in the same direction asthe fundamental wave and in the opposite direction. Those in theopposite direction represent minima, and this class includes thecase </) = o for ^=180° with a large component of harmonic. In theprevious work we have taken <^y — o for 0— 180°, but this holds onlywhen there is but one value of <^ for which ^ = 0 in that half limiting values of h to avoid secondary maxima in the wave ofmagnetic flux are given in Table III for O — o and ^=180°. Forother values of ^, the limiting values of h may be taken from thecurves of Fig. OlNOWyVH 488 Lloyd.] Effect of Wave Form upon Traitsfor^ III. 489 m Limiting Values of h 6> = o<^ Q = x^° 3 5 .800 .200 7 .613 .143 9 .490 .111 11 .407 .091 13 .347 .077 15 .302 .067 It will be noticed that the limiting values of h for ^=180° are the same values which g-ive a maximum loss when ^ = 0; viz, // = —* ^ in 100 90 80O O70 tc I 60 ^50UJ H40 zu ^30 u a. 20 10 —- —^ ...^ i. ^^ ^^ ^ ^ ^ ?-^ ~\ X, i ^ ^^ \ \ ~^^ tn :;^ \. ^^ \ \, ___^_ —^ ~~m:^ 9 ? ^^ ^ -^ V \ ^^ ^^ :::^ 3 ^^ ^^ ?^ -^ ^ \ T ~~ == == ^ ^i::^ ^ ^^ 0 10 20 30 40 50 60 70 80 90 100 110 120 130 HO 150 160 170 180=* PHASE ANGLE Q Fig. 3. —Limiting Values of Harmonic. The value of (f)^ is to be chosen from those values of (^ for whidithe emf. curve crosses the axis in the same direction as the funda-mental, and that value of should be taken which will give thelargest average emf. If the curve of the emf. has been plotte
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