ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 145 
25%. Loss in Armature Winding.— The maximum current 
density is 2,030 amperes per square inch, so that the 
maximum loss, in accordance with the data of Fig. 31, 
will equal 520 x 10 = 5,200 watts. 
258. Weight of Teeth.—tThe effective volume of a tooth is 
expressed by 0.9X rxX1lxX1= 1.58 X 9.5 X 2.05 X¥ 0.9 = 
- 28.0 eubie inches; so that the weight of all the teeth 
will be 72 X 28 x 0.28 = 570 lbs. where the specific weight 
of the iron is taken as 0.28 lb. per cubic inch. 
259. Loss in Teeth.—<According to Par. 232, the méan tooth 
density is 84,000 lines per square inch, resulting in a 
hysteresis loss of 11 watts at a frequency of 100 and an 
eddy current loss of 5 watts per lb. of iron at a similar 
frequency. 7 
In the present case, the frequency being 50, the specific losses 
are, hysteresis 5.5 = 14+ watts and eddy current $ = 1.25 
watts per lb., thus making in all, a total loss in the teeth 
of 570 (5+ 1.25) = 3,550 watts. 
260. Weight of Core.—The weight of the armature core 
3 above the slots equals 
(76? — 59.1’) x 3.14 
4 
where 76 inches is the external diameter, 59.1 inches the 
internal diameter of the core, and 9.5 inches is the arma- 
ture length which includes the insulation between the 
laminations. 
x 9.5 X 0.9 X 0.28 = 4,300 lbs., 
261. Total Loss in Core.—In Paragraph 235, the corre- 
sponding magnetic density is given as 28,600 lines, which 
implies a loss of 1.9 watts per lb. as hysteresis loss, and 
0.9 watt per lb. as eddy current loss, both figures caleu- 
lated on the basis of a frequency of 100. 
For this machine the hysteresis loss equals 0.95 watt per 
lb. and eddy current loss, 0.225 watt per lh. 
