1

What is the component of a DC generator that converts the armature AC into DC?

commutator

What provide(s) the magnetic field necessary for the operation of a DC machine?

pole pieces

When increasing the amount of output voltage when a loop contains 20 turns of the wire, how much was the inducedvoltage increased?

20 times greater than that for a single-loop conductor

A square wave voltage varies between 0 V and 12 V. The positive pulses are 75 μs wide and there is a 25 μs gap between them. What is the DC average of the waveform?

9 V

The brush leads are generally marked with ________.

A1 and A2

_______________ is the twisting or bending of the magnetic lines of flux of the pole pieces.

Armature reaction

Because the fields of PM motors are permanent magnets, the field flux remains ________ at all times.

Constant

______________ is a measure of the useful electric energy produced by the generator.

Countertorque

The simplest method of setting the brushes to the neutral plane position is to connect a DC voltmeter across the series field leads.

False

There may be occasions when one DC generator cannot supply enough current to operate the connected load. When this occurs, another generator is connected in series with the first.

False

A device that converts electrical energy into mechanical energy is called a(n) _____

Motor

A compound motor has _____ field windings.

Series and shunt

Because brushes are made from a material that is softer than the copper bars of the commutator, this permits the brushes to wear instead of the commutator.

True

Flashing the field results in polarity of the output voltage being reversed when the machine is restarted as a generator.

True

What is a device that converts mechanical energy into DC electrical energy?

a generator

In a compound DC motor control circuit, the field loss relay will disconnect the _____ if power is lost to the _____.

armature; shunt field

The _____ ride against the commutator segments and are used to connect the armature to the external circuit of the DC machine.

brushes

What type of DC motor uses a rotor shaped like a hollow cylinder or cup?

brushless

The motor that does not contain a wound armature, commutator, or brushes is the _____ motor.

brushless dc

Brushes are made from a material that is softer than the __________ bars of the commutator.

copper

A compound generator has both series and shunt field windings. When those windings are connected so they aid each other in the production of magnetism, that connection is called _____.

cumulative-compound

The compound motor connection that should generally be avoided is the _____.

differential

A compound generator has both series and shunt field windings. When those windings are connected so their fields oppose each other in the production of magnetism, that connection is called _____.

differential-compound

The output voltage of a generator is usually controlled by the amount of _____.

field excitation current

When using the right-hand motor rule, what indicates the direction of the field flux?

forefinger

Permanent magnet motors have _____ efficiency than conventional field-wound motors.

higher

In a compound generator, which connection has the shunt field connected in parallel with both the armature and series field?

long shunt

Shunt generators contain only a shunt field winding connected in _____ with the armature.

parallel

What king of magnets does the armature or rotor of a brushless DC motor contain?

permanent

The speed of the disc servomotor can be varied by changing the amount of voltage supplied to the armature. The voltage is generally varied using _____.

pulse-width

During a 360° rotation of the loop, the polarity of voltage remained the same in both halves and waveform.What is this called?

rectified DC voltage

Which type of generator must be self-excited?

series

The DC motor, known as a "constant speed motor," is the _____ motor.

shunt

What type of generator can be either self-excited or separately excited?

shunt

When the field winding of a DC motor is connected in parallel with the armature, the motor is called a _____ motor.

shunt

When a motor is connected as a differential compound, the _____ determines the direction of rotation of the motor at no load or light load.

shunt field

Which of the following is the material of which pole pieces are constructed?

silicon steel

When using the right-hand motor rule, what indicates the direction of thrust of the armature?

thumb

When using a converter, turning the _________ on or off in the proper sequence means that current can be routed through the stator windings.

transistors

The speed regulation of a DC motor is proportional to the _____.

armature resistance

A generator containing both series and shunt fields is called a _____ generator.

compound