52 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
Example 10a.—For one pound of iron made up of 0.02 
inch sheets, the eddy current losses observed are 4.5 watts, 
when the magnetic induction is 80,000 lines per square 
inch and the number of cyeles is 100. What is the loss at 
40 eycles? | 
Solution: The loss at 40 eycles, will be smaller in the 
()? 0? 
a that is, 4.5 X a = 0.7 watt. Ans. 
100°’ 
ratio of 
20 
% 
© 
N 
q 
8 
L 
co 
w 
S 
ds 
LOSSES IN WATIS FER POUND 
SS 
Pd 
fea OE ot ee 
= awe 
7) 20000 40000 60000 £0000 700000 720000 
ZEWSITIES PER SQUARE INCH 
Fie. 29.—IRnon Losses In WATTS FOR DIFFERENT DENSITIES WITH 
A FREQUENCY OF 100 PER SECOND. 
$3. Effect of Machining.—It is important to keep in mind 
that the quality of the iron is much affected by the differ- 
ent operations such as machining, filing, ete., and the latter 
especially favors eddy currents inside the slots. 
94. Armature Copper Losses.—The losses in the armature 
winding of a generator are on the average the smallest item 
