318 



ARMATURE CONSTRUCTION 



or shaped by hand in the same way as wire windings, except that 

 pins would not be employed. 



Fig. 387 shows a 1000-k.w. turbo-alternator armature being 

 wound. The winding is a 4-pole, 3-phase, half-coiled, quintuple- 

 coil spiral winding in two ranges. 



By extending Table XIV. on p. 203, we find this winding t" 

 have 5 slots per pole per phase, which will be seen from Fig. 387 

 to be the number of slots covered by one side of one coil. 



The total number of slots is thus 



5x3x4 = 60. 



There are 2 coils per phase and 3 in each range, making 6 coils 

 in all. The slot contains 6 conductors wound flat, one above the 

 other. 



The winding block is similar to that used in the previous cases, 



FIG. 389. Winding Strip Coil. 



but, instead of the pins used in wire windings, the conductor is held 

 in a slot after threading it through by means of a wedge of fibre or 

 wood in the manner of Fig. 389. This wedge is withdrawn from 

 the slot each time a conductor is threaded through, and insert rd 

 after each conductor is in place until the slot is filled. 



Fig. 388 shows the finished armature. 



Fig. 390 shows an instance of strip-wound coils with the strip on 

 edge in the slots. The coils are shaped by hand, and bent back with 

 a mallet against a wooden backing which will be seen at the front 

 end of the armature core, and which is withdrawn when the coil 

 is finished. It is not easy to hand-wind strip on edge in this 

 manner if the strip is very wide, owing to the difficulty in bending 

 it on edge at the ends. If the coils are straight and not bent 

 back, the difficulty is eliminated ; but with a 2-range (or 3-range) 

 winding one range at least must have its coils bent back. 



A view of a finished armature, with coils wound witli strip on 

 edge in the slots, is given in Fig. 391. 



