Motors 3 Flashcards by London Cabada

The torque produced by a motor overload that pulls the rotor out of synchronization is referred to as ? torque.
Select one:

a.
pull-in

b.
pull-out

c.
reluctance

d.
synchronous

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A ? may be used to start the rotor rotation and speed it up to almost synchronous speed.
Select one:

a.
motor-generator set

b.
permanent magnet

c.
pony motor

d.
static exciter

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If a synchronous motor rotor slips out of synchronous speed for a period of time, ? are needed to shut it down.
Select one:

a.
commutators

b.
compressors

c.
discharge resistors

d.
protective relays

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The current in the stator power circuit is at minimum level when a synchronous motor is at ? power factor.
Select one:

a.
lagging

b.
leading

c.
low

d.
unity

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In an application of ? circuit logic, a motor must be allowed to decelerate by coasting or braking before being changed to a low speed.
Select one:

a.
accelerating

b.
compelling

c.
decelerating

d.
modified

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A circuit with ? circuit logic allows the operator to select the desired speed by pressing either the low or high pushbutton.
Select one:

a.
accelerating

b.
circulating

c.
compelling

d.
dynamic

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? circuit logic is used in applications where a motor or load cannot withstand the stress of changing quickly from high speed to low speed.
Select one:

a.
Accelerating

b.
Circulating

c.
Compelling

d.
Decelerating

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The relative position of the ? in Schrage AC motors is altered to change the speed of the motor.
Select one:

a.
brushes

b.
rotor windings

c.
slip rings

d.
wye connections

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A consequent-pole motor with two poles when wired in series has ? poles when wired in parallel.
Select one:

a.
1

b.
2

c.
4

d.
8

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Damage may occur to an AC motor if the supply voltage is varied more than ? above or below the rated nameplate voltage.

Select one:

a.
3%

b.
5%

c.
10%

d.
15%

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Torque decreases when the voltage is lower than the rated voltage. With 95% of rated voltage, the torque is ? of rated torque.
Select one:

a.
5%

b.
10%

c.
90%

d.
100%

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The frequency of the voltage used to control motor speed is called the ? frequency.
Select one:

a.
alternative

b.
carrier

c.
fundamental

d.
static

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The speed of standard AC squirrel-cage motors is normally varied by changing the number of poles or the ? .
Select one:

a.
applied frequency

b.
current

c.
drive rating

d.
series connection

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? control is a method of controlling the voltage applied to the armature of a DC motor.
Select one:

a.
AC field-voltage

b.
DC field-current

c.
SCR armature-voltage

d.
Sensorless field-current

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A ? bearing is a rolling-contact bearing that has cylindrical or tapered steel rollers confined between inner and outer rings.
Select one:

a.
ball

b.
Conrad

c.
friction

d.
roller

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? roller bearings have a high radial load capacity but are not designed for axial loads and cannot tolerate misalignment.
Select one:

a.
Cylindrical

b.
Ball

c.
Spherical

d.
Tapered

? bearings are used in areas of heavy loads where space is limited.
Select one:

a.
Ball

b.
Friction

c.
Needle

d.
Tapered

A(n) ? clutch uses a magnetic field to couple a motor to a load.
Select one:

a.
coupling

b.
eddy-current

c.
friction

d.
magnetic

A ? is a coupling that connects or disconnects the motor shaft to a drive shaft while the motor is running.
Select one:

a.
clutch

b.
flexible coupling

c.
gear

d.
rigid coupling

? transmit torque to and from a pulley through the wedging action of the tapered sides of the belt in the pulley groove.
Select one:

a.
Chains

b.
Timing belts

c.
Timing chains

d.
V-belts

? misalignment is the situation where two shafts are parallel but are not on the same axis.
Select one:

a.
Angular

b.
Nonparallel

c.
Offset

d.
Springing

The ? alignment method uses two dial indicators to take readings of opposing sides of coupling rims, giving two sets of shaft runout readings.
Select one:

a.
coupling

b.
laser rim-and-face

c.
reverse dial

d.
rim-and-face

A(n) ? occurs when current leaves its normal path and travels to the frame of the motor.
Select one:

a.
dead circuit

b.
ground fault circuit

c.
open circuit

d.
overload circuit

? is the most common causes of motor failure.
Select one:

a.
Misalignment

b.
Overloading

c.
Rotor failure

d.
Single phasing

? is a power supply problem that occurs when one of the 3-phase lines leading to a 3-phase motor no longer delivers voltage to the motor. Select one: a. Phase unbalance b. Single phasing c. Voltage blocking d. Voltage surging

A ? motor is an AC motor that uses induction to create linear movement. Select one: a. compensated universal b. linear induction c. noncompensated universal d. stepper

The main parts of a universal motor are the field windings and the ? . Select one: a. armature b. pigtails c. reverse coils d. rotor

? rely on electric commutation (pulses) to provide motion control. Select one: a. Linear motors b. Servomotors c. Stepper motors d. Synchronous motors

A motor is ? when it draws more than rated current. Select one: a. overcycled b. overloaded c. overshaded d. unbalanced

A(n) ? is a rigid steel support for firmly coupling and aligning two or more rotating devices. Select one: a. anchor b. base plate c. dowel d. foundation

? braking requires more maintenance than any other method of braking. Select one: a. Electric b. Friction c. Magnetic d. Regenerative

Plugging a motor to a stop results in high current and heat. Select one: True False

True

? braking can be used to provide an immediate stop, particularly in an emergency situation. Select one: a. Electric b. Dynamic c. Interlock d. Magnetic

Power resistors are used with ? braking to dissipate the heat of braking. Select one: a. dynamic b. electric c. friction d. plugging

The motor connections are reversed with ? so that the motor develops a reversed torque to brake the motor. Select one: a. friction braking b. plugging c. reversing braking d. rigging