118 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
where (Z C) is the symbol of peripheral density ; m = the 
number of phases; Z—the number of conductors per 
phase of the armature; and C = the current in a’ phase 
winding. 
The data of the ampere conductors per inch periphery, in 
terms of the machine capacity in KVA., indicates a com- 
promise between the items 1 and 3 in Par. 181, as the 
choice of the diameter according to the peripheral density 
takes into account the question of the regulation, the pro- 
vision of the necessary cooling surface, and the winding 
space. 
192. Peripheral Densities for Polyphase Machines.— 
Fig. 63 gives good average values for 50 eycle, low and 
medium tension polyphase alternators. For 25 eycle 
> 
—— | | 
700 = 200 300 = 400 500 600 700 80 900. 4000) 
OT?UT IW KIA. 
Fie. 63.—AVERAGE PERIPHERAL DENSITIES OF STANDARD POLY- 
PHASE ALTERNATORS, 
machines, the peripheral densities may be about 20% 
higher, and for those of a high tension generator about 
20% lower. The average peripheral densities of single 
phase alternators are approximately 80% of the figures 
given for polyphase machines. 
