190 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
field ampere turns will be 2.5 X 48,500 = 121,250; or, 
121,250 
24 
_Assuming that 70 per cent. of the field ampere turns are 
utilized in the air gap, the latter is equal to 0.7 X 5,050 
— © X 0.318 37x 10°, where 6 = 0.8 inch. 
~ 6.8 XK 14.25 e : 
As the value 6 = 0.25 is very close to the correct value, it 
is used in the calculations of this particular machine. 
= 5,050 ampere turns per pole. 
364. Dimensions of Magnetic Circuit.—The principal 
dimensions of the magnetic circuit are as follows, see 
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Fie. 85.—MAG@NETIC Circuit DIMENSIONS OF 520 KVA. , 300 R. P. M,, 
60-CYcLE, SINGLE PHASE ALTERNATOR. 
External diameter of the armature..... 100 — inches 
bore of the armature... :... 5.0.5.7 25.2 87.5 8s 
Slot Widths i405 yon eee een eee OS 
ROE ODE oie ot ps eee ee Pema ye A. 
overall length of the armature, including 
two 14-inch ducts................ 15.6: 
external diameter of the magnet whee).. 87 "3 
pole‘core length fi6:..4c.-34 ele eee 14.25 « 
Puls Bhe Wi Oa eee ee 63.59% 
