ALTERNATING GENERATORS AND SYNCHRONOUS motors. 163 
Now we have to determine whether these ampere turns can 
be placed inside the slots and on the periphery, without 
cutting the insulation of the slots too fine, or driving the 
eurrent density in the conductors too high. 
With regard, to the specified regulation, which in the present 
ease is a stiff condition, the peripheral density should 
be kept within the average value, as indicated in Fig. 63. 
304. Normal Phase Current.—The normal phase current 
175.000 
being 173 x 220° > 460 amperes, the number of armature 
ets mrstloved per phase Will bo <= = 95 
conductors to be employed per phase will be 3759 = 39, 
or the nearest number, which is a multiple of the 12 slots 
available per phase, gives 36 conductors per phase, or 3 
per slot. Therefore, the exact value of total ampere con- 
ductors will be 3 X 36 = 108, and the resulting peripheral 
1°8 X 460 | 
35.4 X 3.14 
per inch, which is a good figure. 
density is equal to = 447 ampere conductors 
305.. Current Density in Armature Winding.—With 
regard to the low tension of the alternator, an insulation 
thickness of 0.045 inch micanite is more than sufficient. 
For the three conductors, the size and shape of the slot is 
most suitable, if one conductor is composed of 8 parallel 
connected No. 6 8S.W.G. round wires, each having a double 
cotton covering. As indicated in Fig. 75, the wires may 
be arranged in 8 layers. 
The total sectional area of a conductor is 8 X 0.02895 = 
0.2316 square inch; the current density will, therefore, be 
460 
0 > 1,980 amperes per square inch, which is a mod- 
erate value and will assist in obtaining the specified 
efficiencies. 
306. Magnetic Density in Teeth.—The next step is to fix 
