50 DIRECT-CURRENT DYNAMCS AND MOTORS. 
this stage of the design, the shunt current may be taken 
approximately from Table 18: 
TABLE 18. 
APPROXIMATE SHUNT CURRENT IN SHUNT AND 
COMPOUND-WOUND DYNAMOS. 
Capacity, in Kilowatts. Shunt vase! ‘Gee of 
cap | 15% to 12% 
5 10 ee 
1 8 ee 7 
2.5 7 ieee... 
5 6 Seu 
10 5 (6. 
Q5 4 6é 3 
- 50 to 100 3 arene 2 
100 ‘* 300 26° Se 
500 and over. 2 fr eee 
To obtain the current in the armature, the shunt current 
must be added to the desired current output, in case of a 
generator; and deducted from the given supply current, 
in case of a motor. 
44. Power Lost by Hysteresis.—The hysteresis loss in the 
armature core is proportional to the frequency of reversal 
and to the mass of iron contained in the core: 
wank fh ieee (29) 
where w, = hysteresis loss, in watts; 
n = hysteresis factor, that is, the hysteresis loss 
in 1 cubic inch of iron at a frequency of 1 
cycle per second, see Table 19; 
f = frequency, in cycles per second; 
and M = mass of iron in armature core, in cubic inches. 
