Deck 1: Operating Principles of DC Generators

Question 1

What is the reason that a generator takes more mechanical power to drive a heavy current load than a light current load?

Answer 1

The reason that a generator takes more mechanical power to drive a heavy current load than a light current load is that the larger the load current through the generator, the larger the counter torque produced.

Question 2

What is done to counteract armature reaction?

Answer 2

To counteract this effect, commutating poles are often inserted between the main field poles.

Question 3

The ____________________ is the component of the generator that has the voltage (EMF) induced into it.

Answer 3

armature

Question 4

The magnetic field of a generator is established by a set of ____________________.

Question 5

Generator ratings as specified by the manufacturer shall be found on the ____________________ of the machine.

Question 6

A self-excited generator develops voltage for either direction of rotation.

Question 7

What generator ratings are generally specified by the manufacturer?

Question 8

The member of a DC generator that spins is called the rotor.

Question 9

The commutator is used to change the DC voltage induced in the armature windings to AC voltage at the generator output terminals.

Question 10

All generators have the same voltage regulation characteristics.

Question 11

Why is it possible to vary the output voltage by controlling either the speed of the prime mover or the strength of the magnetic field?

Question 12

The armature ____________________ generate voltage by cutting a magnetic field as the armature rotates.

Question 13

In the case of generators, what is the difference between brush polarity and electrical polarity of the brushes?

Question 14

In all but a few instances, the output voltage is controlled by varying the field current in the field circuit.

Question 15

Brush polarity markings are often omitted, but the electrician can easily determine electrical polarity by connecting a(n) ____________________ across the output leads of the generator.