¥2 
ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
111. 
112. 
115. 
114. 
415. 
116. 
117%. 
118. 
119. 
120. 
121. 
Give the formule stating the value of the armature ampere 
turns for single-phase, two-phase and three-phase alter- 
nators. ; 
Caleulate the back ampere turns of a 180 KVA., 220 
amperes, star connected three-phase alternator, having 36 
turns per phase. 
Give the equation for the generated E.M.F. of an alter- 
nator. 
A 400 KVA. revolving field type star connected 50-cycle 
three-phase alternator generating a phase pressure of 
2,040 volts has 432 armature conductors per phase and 
a form factor of 2.3. What will be the useful flux per 
pole of this alternator? 
Give the general symbolical expression for the field ampere 
turns per pole. 
For a certain alternator it has been found necessary to use 
a useful flux per pole of 4.12 x 10° lines and a leakage 
factor of 1.25. What will be the flux value in the field 
system ? 
What is the number of ampere turns which is required to 
drive 50,000 magnetie lines per square inch through a 
east iron path having a length of 5 inches? 
An alternator has an external magnet wheel diameter of 
54.6 inches and 12 poles. What is the pole pitch of this 
machine ? 
The pole are length of the above alternator is 8.75 inches. 
What will be the pole are ratio? 
Upon what principal elements does the wave form of the 
E.M.F. of an alternator depend? 
What is understood by “‘long coil windings’’? 
