THE DESIGN OF ALTERNATING 
GENERATORS AND SYNCHRONOUS 
MOTORS. 
REGULATIONS: 
111. Testing of Regulation.—tThe inherent regulation of 
alternators deserves the most careful consideration, as a 
small or reasonable voltage drop is the most satisfactory 
eondition for central station work. 
The direct method of determining the voltage drop, is to 
switch the normal full load on the alternator and measure 
the difference between the no-load and full-load voltage, 
when the excitation current and the speed are kept con- 
stant. When this test is executed under different excita- 
tions, that is, for different no-load voltages, one can see 
how the generator works under different degrees of mag- 
netie saturation. 
A properly designed alternator running at normal speed, 
with its rated normal excitation, should give a voltage drop 
which is only a small fraction of the open cireuit pressure. 
Under these circumstances the generator will feed the line 
circuit satisfactorily without much attendance in the cen- 
tral station. 
112. Workshop Tests.—To ascertain the regulation of a ma- 
chine in the manufacturer’s test room, the method given in 
the above Par. 111 is a very costly experiment, besides it 
is not always possible; therefore an indirect method has 
been devised, which is simple, reliable and cheap in its 
execution. 
