DIRECT-CURRENT DYNAMOS AND MOTORS. 37 
347. 
348. 
349. 
350. 
Compute the winding in case it is desired to over-com- 
pound the machine given in the preceding example for 
a line loss of 6 per cent.; both the series and the shunt 
coils to be connected in series; limit of temperature 
rise, 25°C.; data for magnetic circuit given in Question 
295; speed, 700 revolutions per minute; the armature 
is drum-wound and has a resistance of .01 ohm. 
Calculate a shunt winding for the 2,000 K. W. railway 
generator given in Question 298; temperature rise, 
30° C.; percentage of E. M. F. absorbed by regulating 
resistance, 10 per cent.; all magnet coils connected in 
series; exciting power required, 33,000 ampere turns. 
The machine of the preceding example is to be over com- 
pounded for a loss of 5 per cent ; temperature increase, 
35° C.; all the series coils to be connected in parallel, all 
shunt coils in series; dimensions of machine and mag- 
netic data same as in Question. 298; speed, 70 revo- 
lutions per minute; number’ of armature conductors, 
2,016; armature resistance, .002 ohm. 
A four-pole 25-K.W. direct-driven 150-volt generator is 
designed as fvullows: Armature, smooth ring. 27” ex- 
ternal diameter, 194” internal diameter, 12?” long; 
winding, 14+ coils of 5 turns each; resistance, .036 ohm; 
length of magnetic path in armature core, 15”. Yoke, 
cast iron, octagonal shape, 54” across flats; width, 114”; 
radial thickness, 6’; length per magnetic circuit, 33". 
Magnets, cast steel ; diameter, 9”; length, 52”. Pole- 
pteces, cast steel ; bore, 284’; pole angle, 63°. Speed, 
800 revolutions per minute; factor of magnetic leakage, 
1.3. Compute a shunt winding for a 40° C. rise, al- 
lowing 15 per cent. of output EK. M. F. for shunt regu- 
lator, and taking as cooling area of the coils their cylin- 
drical surface and one end surface. The four shunt: 
coils to be connected in series. 
351. Required a 5 per cent. over compound winding for the 
inachine given in the preceding question. Tempera-. 
