AC Theory ch 31 Word Scramble

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Question	Answer
1. Another name for an AC generator is the ___	alternator
2. What is the primary difference between a simple DC generator and a simple AC generator	Dc uses a comutator AC uses slip rings and brushes
3. There are two basic types of altenator. These are the revolving ___ type and the revolving ___ type	Armature Field
4. Slip rings, unlike the segmented commutator, are contructed as a ___ ring, with each end of the armature loop connected to a seperate ___	continuous, ring
5. In a 3-phase generator, the three sets of windings are placed ___ apart.	120 degrees
6. What limits the amount of power that can be generated with the revolving armature type of generator	brushes and slip rings.. page 234
7.What is the advantae of using a rotating field and a stationary armature on commercial generators	design permits higher kva ratings because he output of circuit is connected to the stator. page 240
8. The ___ is the rotating member of a generator or motor.	rotor
9. When the armature is held stationary in a generator it is called the ___	stator
10. Two tpes of rotating field construction are the ___ rotor and the ___ rotor	salient pole, round rotor
11. Pole faces that jut out and are ery pronounced are called ___ poles.	salient poles
12. The ___ rotor uses a smooth, longer, and narrower construction to minimize wind resistance and centrifugal forces	round
13. Exciters are made in a variety of ways including ___ and ___	stationary, rotating
14. A rotating exciter mounted on the same shaft as the main generator is usually called a ___exciter	brushless
15. Alternators wiht small kVa ratings are usually ___ cooled	Air
16. Air cooled alternator usually have a ___ attached to one end of the rotor to help circulate air.	fan
17. Large-capacity generators are often enclosed in a ___ atmosphere for cooling purposes	hydrogen
18. Which dissipates heat faster, hydrogen or air?	hydrogen
19. What are the factors that determine the frequency of an alternator?	number of poles, speed of rotor
20. What is the mathematical formula for determining the frequency of an alternator?	f = p * s/120 p= # of poles z= speed RPM
21. To generate 50 Hz with an 8-pole generator, the speed of rotation must be ___RPM	750 RPM
22. How many poles are required for a generator to hae a frequecy of 60 Hz at 1,200 RPM?	P = 6 60 = ( 1,200 * P / 120)
23. A generator has four poles and a speed of 1,500 RPM. what is the output frequency?	50 Hz 5- = (4 * 1,500) / 120
24. What three factors determine the output voltage of an alternator?	length of conductors, speed of rotation, strength if magnetic field.
25. How is the output voltage controlled?	increasing or decreasing strength of magnetic field.
26. What three conditions must be met when connection two 3-phase alternators in parallel?	1) ? 2) outputs must be same frequency 3) all output kVa must be same
27. The most common method of detecting when the direction of the magnetic field of one alternator is matched with the phase rotation of a paralleled alternator is with the use of ___	3 lights
28. Using the "Three Lamp" method, houw do yu know when the two alternators are in-phase with each other?	all the lights are out
29. Another method of paralleling two alternator is with the use of a	synchroscope

Created by: JoshHampton