FREE AND STUDY GAMES ABOUT AC THEORY CH 31 EXAM

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FREE AND STUDY GAMES ABOUT AC THEORY CH 31 EXAM

QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -29 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation Question 1: 28. Using the "Three Lamp" method, houw do yu know when the two alternators are in-phase with each other?

Answer:

all the lights are out

Question 2: 1. Another name for an AC generator is the ___

Answer:

alternator Question 3: 17. Large-capacity generators are often enclosed in a ___ atmosphere for cooling purposes

Answer:

hydrogen Question 4: 24. What three factors determine the output voltage of an alternator?

Answer:

length of conductors, speed of rotation, strength if magnetic field.

Question 5: 23. A generator has four poles and a speed of 1,500 RPM. what is the output frequency?

Answer:

50 Hz

5- = (4 * 1,500) / 120

Question 6: 14. A rotating exciter mounted on the same shaft as the main generator is usually called a ___exciter

Answer:

brushless Question 7: 9. When the armature is held stationary in a generator it is called the ___

Answer:

stator

Question 8: 8. The ___ is the rotating member of a generator or motor.

Answer:

rotor Question 9: 10. Two tpes of rotating field construction are the ___ rotor and the ___ rotor

Answer:

salient pole, round rotor Question 10: 19. What are the factors that determine the frequency of an alternator?

Answer:

number of poles, speed of rotor Question 11: 2. What is the primary difference between a simple DC generator and a simple AC generator

Answer:

Dc uses a comutator AC uses slip rings and brushes

Question 12: 29. Another method of paralleling two alternator is with the use of a

Answer:

synchroscope Question 13: 7.What is the advantae of using a rotating field and a stationary armature on commercial generators

Answer:

design permits higher kva ratings because he output of circuit is connected to the stator. page 240 Question 14: 11. Pole faces that jut out and are ery pronounced are called ___ poles.

Answer:

salient poles

Question 15: 18. Which dissipates heat faster, hydrogen or air?

Answer:

hydrogen Question 16: 26. What three conditions must be met when connection two 3-phase alternators in parallel?

Answer:

1) ?

2) outputs must be same frequency

3) all output kVa must be same Question 17: 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 ___

Answer:

• lights

Question 18: 25. How is the output voltage controlled?

Answer:

increasing or decreasing strength of magnetic field.

Question 19: 15. Alternators wiht small kVa ratings are usually ___ cooled

Answer:

Air Question 20: 22. How many poles are required for a generator to hae a frequecy of 60 Hz at 1,200 RPM?

Answer:

P = 6

60 = ( 1,200 * P / 120)

Question 21: 3. There are two basic types of altenator. These are the revolving ___ type and the revolving ___ type

Answer:

Armature Field Question 22: 4. Slip rings, unlike the segmented commutator, are contructed as a ___ ring, with each end of the armature loop connected to a seperate ___

Answer:

continuous, ring Question 23: 21. To generate 50 Hz with an 8-pole generator, the speed of rotation must be

___RPM

Answer:

750 RPM

Question 24: 16. Air cooled alternator usually have a ___ attached to one end of the rotor to help circulate air.

Answer:

fan Question 25: 5. In a 3-phase generator, the three sets of windings are placed ___ apart.

Answer:

120 degrees