84 



SYNCHRONOUS MOTORS 



in which, as before, h is the total number of hours that the plant operates 

 per annum. 



Numerical Example. Let us take the same case of power-trans- 

 mission already mentioned in which the total power to be transmitted 

 k.w. is 500 the distance 10 kilometers, and the potential difference, 

 at the receiving point, 5000 volts. 



Let us assume that the total impedance of the synchronous motors 



ual lost afeneiyy due t lato efficiency 

 of synchronous motors. 



FIG. 40. 

 TABLE III 



is 15 ohms, and that the plant is in operation a total of 3000 hours 

 per annum. On substituting the corresponding numerical values in 

 the preceding formulae, and making the calculations we obtain data 

 from which Table III (page 78) has been prepared, the results being 

 shown graphically in Figs. 39 and 40. 



The line parallel to the axis, in Fig. 40, represents the annual 

 loss of energy due to the decrease of efficiency of the synchronous 

 motors. 



