. Electrical world. s obtained respectively from the curves of Figs. I and 2. C is dependent upon the ratio —. in which ? =r T core length between flanges. In the curves for C suitable allowanceis made for the inductance of the end connections. O is dependentupon ^ X H. in which H equals the average of the number of slotsper pole on stator and rotor. In the curve for C> suitable allowanceis made for the so-called zig-zag dispersion over the heads of theteeth. The curve of Fig. 2 shows the great importance of employing ahigh value for A X H. for below the curve rises rapidly andgenerall
. Electrical world. s obtained respectively from the curves of Figs. I and 2. C is dependent upon the ratio —. in which ? =r T core length between flanges. In the curves for C suitable allowanceis made for the inductance of the end connections. O is dependentupon ^ X H. in which H equals the average of the number of slotsper pole on stator and rotor. In the curve for C> suitable allowanceis made for the so-called zig-zag dispersion over the heads of theteeth. The curve of Fig. 2 shows the great importance of employing ahigh value for A X H. for below the curve rises rapidly andgenerally renders futile any attempt to improve the power factorbv means of decreasing the radial depth of the air-gap. This zig-zag dispersion is almost negligible with many slots and moderately 8o6 ELECTRICAL WORLD and ENGINEER. Vol. XLIII, No. i8. a g II O O O O < b SbSiSH^ ec c- — .h H:25 izzzzzzaSuSjaS <b i i i-I.$ll^i., ?1 z ;£2<si:: ill||!|^|^J5^ii I a 3 £^ N ° ^ « ~ « s I g . g i ^X XXX i<]S. a OS 2 - X > o z zzzzzaauS Apkil 30. 1904. ELECTRICAL WORLD and ENGINEER. ° i = £ ? 9 ^. ^ .5 •» a p ° * a Hid : °i lie S SE ;t« z 2: « < s ^ £ „ ° I I ~ deep air-gaps, but with few slots and short air-gaps it may riseto a verj- high figure, and thus it appears that very short air-gaps,besides being mechanically undesirable, lead to far less gain than isgenerally believed. The range of satisfactory practical designsgenerally lies between values of and for /\ X H, though ? 1 1 J 1 V 1 a = Radial Depth of Air Gap in cm. 125 \ H = No. of Slots per Pole (Mean for \ StatorftRotor) ^ ? 1 0 \ 1 1 \ ! \ g .95b .85 N K \ \ s s \ •v \ .65 ^ • 2 .4 .6 .8 3-4 2,6 >: HFIG. 2.—CURVE. for very small motors, values less than must occasionally beused, and a precise predetermination of ? is then rendered difficultowing to the inaccuracy in estimating the zig-zag
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
