154 
ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
284. 
285. 
286. 
The total weight of armature copper is equal to 
2 X 42,500 X 0.03258 x 0.32 = 885 lbs. 
Teeth Density.— With regard to the specific utilization 
of the iron material, we find in Par. 178, a magnetic 
density in the teeth of 77,000 lines per square inch, which 
is a good average value, see Fig. 27. 
The density in the armature core above the slots has been 
calculated as 22,400 lines and is a comparatively low value. 
Weight of Armature Iron.—tThe total weight of the 
armature iron is composed of, 
the weight of the teeth, 
256 X 5.5 X 1.33 X 2.16 X 0.9 X 0.28 = 1,020 lbs., 
and the weight of the armature core, 
186° — 173.77 
4 
_ from which we obtain a total of 5,860 Ibs. 
This value does not compare favorably with the data in 
Fig. 14, though the output factor is found equal to that 
of a standard machine. 
3.14 x 5.5 x 0.9 x 0.28 = 4,840 lbs.; 
Losses in Armature Iron.—The iron losses in the 
different parts of the armature are as follows: 
The hysteresis loss per lb. of material in the teeth with a 
magnetic saturation of 77,000 lines, will, in accordance 
with Fig. 29, be equal to 9.6 x = = 4.8 watts, for a 
periodicity of 50. 
Under the same conditions, the eddy current losses are 
1.05 watts per lb. of material, so that the losses in the 
teeth amount to 1,020 x 5.85 = 5,960 watts. 
The armature core, with its low degree of saturation, has 
the specific losses of 0.65 watts per pound in the form of 
hysteresis and 0.12 watts loss due to the eddy currents; 
