10 
ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
Rn) 
a 
96. 
101. 
102. 
103. 
104. 
What is the cause of inductive voltage drop in an a.ternator 
and how is it expressed? Give the formula of the load 
characteristic. 
From the experimental machine characteristics of a 375 KVA. 
polyphase alternator as given in answer to Question 89, 
determine the inductive cos ¢ = 0 load characteristic for 
60 amperes armature current, which on the short circuit 
characteristic corresponds to 1,800 ampere turns excita- 
tion, by applying the approximate method of Prof. Arnold. 
Give the exact expression of the inductive load characteristic 
which takes into account the different degrees of magnetic 
saturation of the alternator. 
Apply the graphical method for determining the inductive 
cos P = 0 load characteristic of an alternator, the data 
of which is given in Question 95. 
Determine the drop for the same armature current as given 
in Question 95 but with a power factor of cos y = .8. 
What principal elements affect the inherent regulation of an | 
alternator ? 
State the different paths of one closed magnetic circuit in 
an alternator. 
Represent graphically a closed magnetie circuit of an alter- 
nator. 
Give the symbolical expression for magnetic reluctance. 
Give your reasons for the necessity of an accurate deter- 
mination of the machine characteristics in designing an 
alternator, such as the example given in Paragraphs 140. 
and 141 of the Instruction Book. 
With reference to Fig. 42 in the Instruction Book, give the 
symbolical expression of magnetic reluctance of the field 
system of one pole and calculate same from the dimensions. 
of the particular 12-pole machine illustrated in the accom- 
panying Fig. 1. 
