WINDING OF CONTINUOUS-CURRENT ARMATURES 273 



copper with a length of 230 cms., and measuring in section 12'0 

 mm. x 2-5 mm. The weight of copper required may be calculated 

 from the section of the conductor and length of the turn. The 

 cross-section is 1*2 x 0*25 = 0*3 sq. cms., and the mean length of 

 one turn is 230 cms. The weight of a cubic centimeter of copper 



FIG. 323. Developed View of Winding of 250 k.w. Generator. 



is 8-9 grams, and hence the weight of one turn is 23QxQ ' 3x8 ' 9 = 



0'615 kgs. As there are 600 turns the total weight of strip 

 copper required is 630x0-615 = 387 kgs., or about 0'4 ton. The 

 copper constituting this strip must be specified to have its edges 

 well rounded. The principle of the machine by means of which 

 the bend at the back end is effected, is that of the tool shown in 

 Fig. 324. 



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