ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
16. 
a7; 
18. 
19. 
20. 
21. 
22. 
‘What are the usual number of slots allowed per pole? 
State the average permissible temperature rise for the differ- 
ent parts of a generator? . 
What is the usual value of short cireuit current in a well 
designed alternator, and why should it not be exceeded ? 
What degree of insulation should the armature and field coils 
possess ? 
Mention some of the mechanical features of a modern alterna- 
tor. 
What benefits are obtained from the use of higher efficiencies 
than those given in Tables 1 and 2 in the instruction book, 
from the central station engineer’s point of view as well 
as from that of the manufacturer? 
State the advantage and disadvantage of a smaller voltage 
drop than that given in answer to Question 11. 
What advantage has an alternator with the E. M. F. of prac- 
tically a sinusoidal wave form? 
What would be the disadvantage in having a greater number 
of slots per pole than that given in answer to Question 12? 
Up to what size is the carcase or shell cast in one piece and 
why is this not done for larger machines? > 
What material is employed for armature core stampings; 
what is their usual thickness, and how are they assembled ? 
What is the object of laminating the armature core? 
‘What is the most reliable insulation used between the arma- 
ture core stampings? State the usual thickness of same. 
What is understood by the effective iron volume of the arma- 
ture core? State its average value. 
What means are used to obtain perfect solidity of the arma- 
ture core around the teeth? 
Why is the inner surface of the armature core not machined ? 
