DIRECT-CURRENT DYNAMOS AND MOTORS. 27 
usually employed for generator and motor armatures. 
Columns 6 to 9 refer to Double Cotton-Covered (D. C. C.) 
wire, this being the kind of insulation usually employed 
on conductors for armature winding. Wires larger than 
No. 5 B. & S. are commonly not used, on account of the 
greater difficulty of handling and winding; if a larger 
area than 33,000 circular mils is required, two wires of 
one-half, or three wires of one-third the requisite cross- 
section, etc., are used. 
ae SAD 
Elect. Engineer ‘nstitute 
Fic. 15.—FLOwW oF CURRENT IN Fic. 16.—FLow or CURRENT IN 
Cross CONNECTED MULTI- MULTIPOLAR Two-CrircvulT 
POLAR ARMATURE. WINDING. 
22. Examples showing Use of Winding Table.—The 
use of the various data given in Table 13 is seen from 
the following example. Suppose an 78x 25 inch smooth 
drum armature is wound to a height of about .6 inch 
with No. 5B. & S. wire, this size being determined, as 
shown in Pars. 23 to 25, by finding the requisite cross- 
section for the current to be earried’ and comparing the 
result with the figures given in the third column of Table 
13. 
The periphery of the armature is 18 X 2 = 56.55 inches; 
hence, by column 7, the number of wires per layer, when 
allowing 8 per cent. of the armature circumference for 
division strips and spaces, is 56.55 X .92 x 5.1 = 265. 
The number of layers is .6 X 5.1 = 3; hence there are, 
in all, 265 X 3 = 795 wires on the armature. 
