80 



SYNCHRONOUS MOTORS 



The depreciation of the machinery, which is higher than that of 

 copper and also the consumption of energy required by the motors, 

 (which latter is not compensated by the decrease in the losses of the 

 generators), have the effect, together, of offsetting the saving made 

 in copper, even through it may be somewhat important. 



Economy of Compensation for the Distributing System by Means 

 of Synchronous Motors Running with Load. There may be some 



30.000 



25000 



30000 



5.000 



6.000 



FIG. 38. 



hesitation in regard to the choice, in this case, because the efficiency 

 of synchronous motors is generally lower than the efficiency of induc- 

 tion motors, and, besides, in order to produce a leading current, they 

 must have a counter E.M.F. higher than that of induction-motors. 

 The effect of this is to increase their rating and their cost. It is there- 

 fore better, in each particular case, to consider whether the use of syn- 

 chronous motors is advantageous or not, from an economic point of 

 view, due consideration being given to the necessities of the case. 



