ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 133 
The ratio between the slot depth and width-is equal to 
45 «208 
So are) pate 
which is a good average value. 
224. Arrangement of Wires in Slots.—The 36 No. 9 
S.W.G. wires, each wire. with an external insulated 
diameter of 0.16 inch, are most conveniently arranged 
inside the slots as indicated in Fig. 69. 
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0020086080098 
Fie. 69.—SLor WINDING OF THE 400 KVA., 3,500 Votts 3-PHASE 
ALTERNATOR. 
225. Calculation of Slot Width.—The slot width is eal- 
culated as follows: The four wires in one row require a 
space of 4 x 0.16 = .64 inch; the 0.08 inch thick micanite 
tube takes up 0.16 inch. Further, it is necessary to allow 
about 0.04 inch as play and 0.04 inch for the irregularity 
of the assembled stampings, thus making a total width of 
0.88 inch. 
226. Calculation of Slot Depth.—The determination of the 
slot depth is earried out as follows: Nine times the 
diameter of the wire is equal to 9 X 0.16 = 1.44 inches, see 
Fig. 69; the micanite occupies 0.16 inch; for play it is 
necessary to add 0.10 inch, and the fixing wedge requires 
an additional 0.25 inch, thus giving a total depth of 1.95 
inches. In the actual machine a standard slot of 0.9 inch 
by 2.05 inch has been employed. 
