Deck 2: Separately Excited DC Generator

Question 1

What happens if the field circuit is closed momentarily with the battery connections reversed?

Answer 1

If the field circuit is closed momentarily with the battery connections reversed, the residual flux reverses and the brush polarity reverses.

Question 2

The output voltage of a separately excited generator can be varied by adjusting the speed of the ____________________ or the field current.

Answer 2

armature rotation

Question 3

If the machine is stopped and then driven in the opposite direction, the ____________________ is cut in the opposite direction and the brush polarity changes.

Answer 3

Falseield flux

Question 4

Brush polarity changes when the field current is zero.

Question 5

How can a field rheostat be used to vary the output voltage?

Question 6

The magnitude of the voltage depends on the rate at which the flux is cut.

Question 7

Residual flux is caused by the residual magnetism left in the ____________________.

Question 8

____________________ the resistance increases the output voltage.

Question 9

How is magnetic saturation achieved in a separately excited DC generator and what is the impact?

Question 10

In a separately excited generator, an output voltage increase is ____________________ to an increase in the armature speed.

Question 11

What causes residual flux?

Question 12

How is the upper limit of the voltage determined?

Question 13

If both the armature direction and the direction of the field current change, the brush polarity remains the same.

Question 14

Field control of the output voltage is accomplished by varying the total resistance of the field circuit with a field rheostat.

Question 15

The brush polarity in a separately excited generator cannot be changed by reversing the rotation of the armature or the direction of the field current.