76 
ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
It is particularly pointed out, see Par. 115, that the absolute 
values of R are not required, as the shape of the curve is 
sufficient. 
EXCIIATIO COE A eer: 
mS ad | 5 £0 ‘5 20 26 a wo 45 ‘ 
ze tr | | | 
‘ Me IaAaw . : 
4000 7 i 
SI 3000 é J lee 420 S 
: 2000 LAA \ 50 N 
tooo 4 AZT e 40 S 
5 / 8 S SI 
44 oo * S 
Fie. 37.—DETERMINATION OF THE INDUCTIVE Cos @ = 0 
REGULATION OF ALTERNATORS FROM THE No-LOAD 
AND SHORT CIRCUIT CHARACTERISTICS. 
AS Calculation of Inductive Regulation.—To deter- 
mine the inductive regulation, proceed as follows: From 
the short circuit characteristic, take the field ampere turns 
corresponding to the current value for which the drop is 
to be obtained and deduct this number from the field 
ampere turns, corresponding to the particular field excita- 
tion for which the regulation is to be found. ° 
In the present case the excitation is given in amperes and 
not in ampere turns; therefore, take the exciting amperes 
corresponding to an armature current of 26 amperes on 
the short circuit characteristic, namely, about 5.06 amperes, 
and deduct this from the field current (OA) of, say, 30 am- 
peres, so obtaining the point £ on the abscisse line, Fig. 37. 
Erect at this point Y a perpendicular and mark on it the 
point C, on the horizontal through R,?. Draw the line 
A C until it euts the curve representing the square of the 
