ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 155 
consequently the total core loss will be 
4,840 x 0.77 = 3,740 watts. 
It will be noticed, that in the present design the iron losses 
in the teeth are far in excess of those in the core, which 
is to be considered an unfavorable method of dissipating 
the energy loss in the form of heat. The amount of the 
total iron losses is very close to the utmost limit of the 
usual values. 
287. Temperature Rise.—With regard to the temperature 
rise of the armature body, we find for the total energy 
waste of 
8,200 + 5,960 + 3,740 = 17,900 watts, 
a cooling surface composed of an 
internal cylinder of 169 x 3.14 X 6 = 3,150 sq. in.; an 
external cylinder of 186 X 3.14x6=3,500 ‘‘ ‘“‘ ; 
8a?—169, 4? 
two side faces of 2 x : , ft x 314 = 9,200 “ ** sand 
two faces inside the air duct of 9.200 °° «** 
a 
offering a total cooling surface of 25,050 sq. inches. 
From Equation (40) a temperature rise of 
T, —15 x 66055 — 54°F. is obtained, 
which, compared with the actual measurement, is found 
somewhat low, especially around the teeth and winding, 
where the greater part of the losses appear. 
288. Flux in Field System.—For the determination of the 
flux in the field system and calculation of the open cireuit 
and short circuit characteristics, refer to Pars. 178 and 
179, in which are found the value for the leakage factor 
o=—1.52 and for the constant k,=1.33. Such high 
values are to be anticipated in the ease of alternators 
with a great number of poles and small iron length. 
The normal density in the pole core has been found equal 
to 100,000 lines, which is a favorable degree of saturation 
