CHAPTER XV 

 OPERATION AND CARE OF ELECTRIC MACHINERY 



137. Location. In selecting the proper location for an 

 electric machine the two principal points to be kept in 

 mind are first, a machine must be kept dry and second, 

 it must be kept free from dust and dirt. If these two require- 

 ments are not satisfied a motor or generator will soon 

 deteriorate and develop faults. 



Effect of Moisture. If moisture is allowed to accumulate 

 on or around a dynamo-electric machine, the machine 

 will very soon be more or less grounded. A machine 

 is said to be grounded when any part or parts of the electric 

 circuits are connected to the frame work (field casting, 

 armature core, etc.) Such a grounding of the winding 

 may be very dangerous for the operator; in the case of a 

 high-voltage generator or motor it might cause a fatal 

 shock if the operator should come in contact with the 

 frame work when he is standing upon a concrete floor or 

 some other partially conducting surface. This point will 

 be more fully discussed in the section on faults. 



Beside the possibility of grounds, there is that of the 

 windings becoming short circuited due to moisture. This 

 is especially likely to occur by the development of two 

 grounds, on different parts of the windings. A machine 

 which develops a short circuit is sure to be seriously damaged 

 by burning unless the fault is at once discovered and 

 removed. 



Effect of Vibration. Of course, in choosing the location 

 for a machine care must be exercised that a firm foundation 



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