. Electrical world. considered to beindependent of the load current. The variable loss is due almostexclusively to the copper loss in the armature winding. The rotary converter with constant impressed alternating as a direct-current generator, tends always to produce thesame direct external The apparent measurable pressure,however, drops off as the load is applied, due to the copper loss ofthe armature, and such drop is a direct measure of the loss withinthe armature. At any chosen value of load current the sum of this loss in wattsadded to the output watts of the conve
. Electrical world. considered to beindependent of the load current. The variable loss is due almostexclusively to the copper loss in the armature winding. The rotary converter with constant impressed alternating as a direct-current generator, tends always to produce thesame direct external The apparent measurable pressure,however, drops off as the load is applied, due to the copper loss ofthe armature, and such drop is a direct measure of the loss withinthe armature. At any chosen value of load current the sum of this loss in wattsadded to the output watts of the converter gives a value whichwould be directly determined by the product of the direct its no-load value and the load current at its chosen value. Itthus appears that with load amperes plotted as abscissas and wattsas ordinates the curve of armature output plus copper loss due toload current is a right line and may be drawn at once for any valueof output current (Fig. i). The ratio of the watts loss in the arma-. FIG. I.—characteristics OF ROTARY CONVERTER. ture copper, due to any load current, to the value of the load currentgives the effective value of the armature resistance. Knowing the no-load losses of the converter and the effective ar-mature resistance the complete performance may be calculated asfollows: Let W = no-load watts input, R = effective armature = no-load direct ,/ = any chosen value of load current;then I^R ^= copper loss of armature due to load, E — I R ^ apparent external direct + EI — input,EI — I^R = output,EI — I^R = efficiency, EI + Wwhich becomes a maximum when I-R = iV, as a close should be noted that the losses are IV -+- I^R. and that while theratio of £ / to W -{- I^R is a maximum when I-R = IV, at any ar-mature load current, /. the input is IE -\- IV and not simply was given in Electrical World and Engineer April 30, 1904,page 824. 1078 ELECTRICAL WORLD and ENGINEER. Vol. XLIII, No
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
