MOTIVE POWER 489 



The following table indicates approximately the consump- 

 tion of current for different size motors operating on a 

 no-volt circuit: 



34 horse power, 2Y2 amperes, or 275 watts 

 Y2 horse power, 4^ amperes, or 500 watts 



1 horse power, 9 amperes, or 990 watts 



2 horse power, 17 amperes, or 1 .97 kilowatts 



3 horse power, 26 amperes, or 2 . 86 kilowatts 

 5 horse power, 40 amperes, or 4 . 40 kilowatts 

 7^/2 horse power, 60 amperes, or 6.60 kilowatts 

 10 horse power, 76 amperes, or 8.36 kilowatts 

 15 horse power, 112 amperes, or 12.32 kilowatts 



It will be noted that the current consumption per horse 

 power gradually decreases as the motor size increases. 



In the care of an electric motor the following points should 

 be noted: Provide sufficient good oil to the bearings, but do 

 not flood with oil. Keep motor clear of dust and oil. Keep 

 all connections tight. Do not overload motor. Protect the 

 motor by fuses and circuit breaker. 



Wind motors. A windmill is one of the oldest sources 

 of power. Its cheapness in first cost and maintenance makes 

 it worthy of consideration where a small amount of power is 

 required and where time is not an element to be considered- 

 Its use at the present time is limited almost exclusively to 

 the pumping of water, and even for that purpose it is being 

 superseded by the small gas engine. The windmill is liable 

 to damage by wind and lightning during storms, and in very 

 calm weather there may not be sufficient wind to operate it. 

 A windmill tower should always be built high enough so 

 that the base supporting the wheel is as high as the trees 

 and buildings in the immediate vicinity. 



The power which a good windmill will develop varies 

 directly as the velocity of the wind, directly as the square 

 of the diameter of the wheel, and inversely as the speed of 

 the wheel in revolutions per minute. Calculations made on 

 this basis are very close approximations. The above rule 

 is deduced from a series of tests made upon various types 



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