194 
ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
369. 
370. 
371. 
372. 
373. 
Temperature Rise.—The hot resistance of all the coils 
in series is 2s * ne - Xx a = 3.45 ohms; and the 
maximum value of excitation energy required will be 
46.5? X 3.45 = 7,400 watts. 
Therefore, the temperature rise will be equal to 7,= 
100 X 7,400 
8,870(1 + 0.0002 X 6,000) 
is equal to 8,870 square inches and the mean value of 
speed, 6,000 feet per minute. 
= 38° F., as the cooling surface 
Copper Loss in Armature.—tThe length of mean arma- 
ture is 77 inches and the resistance of the winding 
48x6x 77_ 8 
6X 0.0162 9° 107 = 0.225 ohms; consequently, the arma- 
ture copper loss for full load is 186? 0.225 = 7,750 watts. 
Tron Loss in Teeth.—The magnetic density in the 
teeth being 72,500 lines per square inch, the loss per pound 
of iron will be 5 watts due to hysteresis and 1.26 watts 
due to eddy currents. 
Therefore, the toothed part of the armature, BT NERS 1 080 
pounds, creates a loss of 6.26 X 1,080 = 6,750 watts. 
Tron Loss in Core.—The weight of the armature core 
_ is 4,900 pounds, and the saturation 32,000. Therefore, the 
iron loss therein will amount to 1.55 x 4,900 = 7,600 watts. 
Temperature Rise in Armature.—The sum of all 
the losses in the stationary armature is equal to 7,750 
+ 6,750 + 7,600 = 22,100 watts, and the radiating surface 
is 21,250 square inches. 
Therefore, the temperature rise will barely exceed 75 X' 
22.100, ‘ 
21 250 3, go 
520,000 
Efficiency.—The full load efficiency is equal to 557,500 
