50) ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
ings is about 0.8 to 1.2 watts per lb. of effective iron ma- 
terial. 
90. Choice of Magnetic Densities.—The choice of ‘the 
magnetic densities for different frequencies is based on the 
loss of 0.8 to 1.2 watts per Ib. when fixing the induction in 
the iron, the object being to keep the losses the same per 
unit amount of material. 
(200 
ei Lf 
10000 4, ms 
9000 f, ‘ 
J ‘es 
200 
LQ8SES IN WATTS 
0 700 200 300 400 500 600 (00 500 Goo 4000 
OUTPUT IN KVA. 
Fie. 28.—AVERAGE IRON LOSSES FOR DIFFERENT SIZES OF 
ALTERNATORS. 
In Par. 91 some very useful data are collected, showing the 
total losses resulting from the hysteresis and eddy current 
losses in laminated armatures. It may be pointed out that 
if a lower efficiency is permitted the magnetic saturation 
