184 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
mal current, the energy loss will be 3462 X 0.0156 = 1,866 
watts per phase, or 5,600 watts total. 
351. Loss in Teeth.—The weight of the teeth iron is 72 X 11 
x 1.4 Xx 1.75 X 0.9 X 0.28 = 490 pounds, and the normal 
saturation being 89,000 lines per square inch, there will 
be a hysteresis loss of 490 X 3 = 1,470 watts and. an eddy 
eurrent loss of 490 < 0.35 = 170 watts. 
352. Loss in Core.—The weight of armature core is equal to 
66? — 6? 
——_ * 3.14 X 11 X 0.9 x 0.28 = 3,900 pounds. 
The losses due to hysteresis and eddy currents are equal to 
1.15 watts per pound of iron, at a density of 47,300. There- 
fore, the total loss in the core is sc to 3,900 X 1.15 
= 4,500 watts. 
353. Cooling Surface and Temperature Rise.—The 
cooling surface consists of: 
The inner cylindrical surface...... 1,800 square inches, — 
the external cylindrical surface..... 2,400 °° *£ 
pix wide faees: «gos cco seen 9:900, ..* "ss 
making a-total of............. 14,100 square inches. 
From the above the temperature rise will be 
tie 4 shen = 63" 8. 
14,100 
354, Efficiency.—Assuming a value of 5,400 watts for losses 
caused by friction and ventilation, tive full load efficiency 
‘ of the alternator will be 
300.000 
3Uu,00U-+-5, 600-+6, 140-+-4,300-++5,40U 
which is somewhat better than specified, see Par. 330, 
but as there is always a sort of uncertainty in the caleu- 
lation of the same, no alteration should be made in the 
= 93.4 per cent., 
