SHORT-CIRCUIT CURRENT AND LEAKAGE FACTOR. 



peres at 1900 volts to the various voltages in the diagram. The in- 

 crease of the magnetic reluctance of the main field through the open- 

 ing of the slots proved too small to influence the magnetizing current 

 in any perceptible manner. 



We see that for voltages above 600 the curves A, B, and C converge ; 

 ir other words, the short-circuit current at the full voltage of 1900 

 will be almost the same whether the slots are open or closed. Hence 

 the maximum flow of energy which can be impressed upon the motor 

 is by no means so much dependent upon the form of the slot as would 

 appear at first sight. The tendency of the closed slot is to change 

 the fundamental diagram in the way shown by the full line curve in 



FIG. II. 



Fig. ii. From this curve follows that, though the maximum power 

 factor is 0.715 instead of 0.755, and the current for the same output 

 58 instead of 55, yet the maximum output of the motor is hardly re- 

 duced as the maximum ordinate of the semi-circle, represented by 

 the broken line, is only inconsiderably larger than the maximum 

 ordinate of the full line curve. If the iron bridges are kept very thin, 

 excellent motors can be built with closed slots, in no way inferior to 

 motors with open slots. The objection to closed slots, then, resolves 

 itself neglecting at present the load losses which may probably be 

 caused by the bridges into a commercial one, viz., the question, 

 Which slot is cheaper? Labor being expensive in America, it is 



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