Deck 32: Three-Phase Alternators

Question 1

The direction of magnetic field rotation is known as _____ rotation.

A) phase
B) loop

Answer 1

A

Question 2

Alternators of small kilovolt-ampere rating are generally _____ -cooled.

A) liquid
B) air
C) hydrogen
D) nitrogen

Answer 2

B

Question 3

What is one factor that controls the output frequency of an alternator?

A) number of stator poles and rotor rotation speed
B) input voltage
C) number of stator poles and number of rotor bars
D) input voltage and torque

Answer 3

A

Question 4

What machines operate on the same principle of electromagnetic induction as DC generators, but they have no commutator?

A) alternators
B) transformers
C) oscillators
D) converters

Question 5

The non-rotating part of a revolving-field-type alternator is called the _____.

A) stator
B) exciter
C) rotor
D) synchronizer

Question 6

By increasing or decreasing the strength of the magnetic field of the rotor, the _______________ of an alternator is controlled .

Question 7

The revolving armature type alternator is capable of _____ power output and is, therefore, _____ often used than the revolving field type.

A) less; more
B) less; less
C) more; less
D) more; more

Question 8

Using a(n) _____ is one method of preventing induced voltage from becoming excessive.

A) paralleling switch
B) inductive bypass
C) field discharge resistor
D) capacitive resistor

Question 9

If one alternator does not produce sufficient power to supply a load, another alternator can be connected to the circuit. The second alternator is connected in _____.

A) series
B) parallel

Question 10

The rotating part of a revolving-armature-type alternator is called the _____.

A) stator
B) exciter
C) rotor
D) synchronizer

Question 11

An alternator containing eight poles per phase is turning at 1500 RPM. What is the output frequency?

A) 70 Hz
B) 80 Hz
C) 90 Hz
D) 100 Hz

Question 12

An alternator that has a separate small alternator mounted on the shaft of its rotor is equipped with a(n) _____.

A) electric starter
B) primary exciter
C) brushless energizer
D) brushless exciter

Question 13

An alternator containing eight poles per phase is turning at 900 RPM. What is the output frequency?

A) 30 Hz
B) 40 Hz
C) 50 Hz
D) 60 Hz

Question 14

The higher power output alternators use a revolving _____.

A) armature
B) field
C) stator
D) exciter

Question 15

_______________ alternators have a fan attached to one end of the shaft.

Question 16

The direct current that is an input to the alternator's rotor is the _____ current.

A) excitation
B) starting
C) synchronizing
D) initiating

Question 17

A three-phase alternator containing six poles is turning at 1000 RPM. What is the output frequency?

A) 30 Hz
B) 40 Hz
C) 50 Hz
D) 60 Hz

Question 18

Power is carried to the outside circuit of a  revolving armature type alternator  via brushes riding against the _____.

A) commutators
B) diodes
C) sliprings
D) wires

Question 19

In order to increase the efficiency of the cooling, some alternators operate in a(n) _____ atmosphere.

A) helium
B) oxygen
C) hydrogen
D) nitrogen

Question 20

A(n) _____ is used to measure the difference in voltage and frequency between two alternators.

A) synchronoscope
B) ohmmeter
C) voltmeter
D) diode