224 



ELEMENTS OF ELECTRICAL ENGINEERING. 



plants in small towns where there is but little lighting during the 

 day, to as much as 0.40 or more for plants in large cities where 

 there is a considerable demand for current during the day. The 

 load factor of a plant which supplies current for an electric rail- 

 way maybe as high as 0.50 or 0.60. The following estimate of 

 the cost of electrical power at the switchboard is based upon the 

 cost of steam power as given in Figs. 138 and 139 and upon the 

 assumption that the plant operates at full-load for 10 hours per 

 day for 308 days per year. 



The electrical equipment of a station costs about $30 or $35 

 per kilowatt of capacity for large stations and somewhat more for 

 small stations. The ordinates of the curve J of Fig. 141, which 

 represent the annual fixed charges on the electrical equipment 



yoo 

 6oo 

 500 

 400 

 300 



200 

 100 



100 200 300 400 500 000 700 BOO 900 



Horse-power of engine. 



Fig. 140. 



per kilowatt of station capacity, are based on a cost of the elec- 

 trical equipment which ranges from $45 per kilowatt for a 100 

 kilowatt station to $35 per kilowatt for a 700 kilowatt station. 



The cost of the additional labor required by the electrical plant 

 is about 25 per cent, of the cost of labor for the steam plant alone. 



