DIRECT-CURRENT DYNAMOS AND MOTORS. 29 
found to be No. 9 B. & §S., having a cross-section of 
12,996 cir. mils. | 
25. Example of Multipolar Armature.—find the ap- 
proximate size of armature conductor for a 200- 
K. W., 6-pole, 550-volt railway generator. 
Solution.—The total current will be 200 x 1,000 + 550 
= 364 amperes, which will be divided between six paths 
if the armature is cross-connected, each conductor car- 
rying 364 + 6 = 61 amperes, and requiring a cross sec- 
tion of 61 x 600 = 36,600 C. M. The nearest larger size 
of wire is No. 4 with 41,616 C. M. If it be desired to 
subdivide this in order to facilitate winding or placing in 
a certain size of slot, it is possible to substitute two No. 7 
wires in parallel, having a combined cross-section of 41,472 
C.M. For a two-circuit winding, each conductor would 
have to carry one-half the total current, or 182 amperes, 
requiring a cross-section of 182 x 600 = 109,200 C. M., 
which is somewhat larger than a No. 0 wire (105,625 C. M.) 
This would be still more clumsy to handle, and might be 
replaced by two No. 3 or by four No. 6 wires in parallel. 
Printed in U.S.A. 
