Chapter 12 - Adjustable-Speed Drives

Question 1

Adjustable-speed drives change the output speed of an electric motor.

Answer 1

True

Question 2

Both mechanical and electrical adjustable-speed drives are widely used in conveyor applications.

Answer 2

True

Question 3

Adjustable-speed drives operate as closed-loop systems only.

Answer 3

False

Question 4

Thyristors are current amplifiers that can start and stop conduction upon command.

Answer 4

False

Question 5

Power semiconductors are used in electrical adjustable-speed drives.

Answer 5

True

Question 6

Some belted adjustable-speed drives are with remote electrical speed adjustment and speed indicators

Answer 6

True

Question 7

All adjustable-speed drives provide a means for starting, stopping, and adjusting the output speed of the drive.

Answer 7

True

Question 8

A dough mixer is a typical constant-horsepower application.

Answer 8

True

Question 9

Solid-state control techniques make step less control possible.

Answer 9

True

Question 10

Wound-rotor drives are available in ratings from fractional hp to 40 HP.

Answer 10

False

Question 11

Analog regulators process current and voltage signals in analog form.

Answer 11

True

Question 12

The term “inverter” refers to equipment that produces an AC output from a DC input.

Answer 12

True

Question 13

CSI drives regulate current rather than voltage.

Answer 13

True

Question 14

One seldom needs to be concerned with environmental conditions when selecting adjustable-speed drives.

Answer 14

False

Question 15

Regenerative braking provides negative torques at any speed.

Answer 15

True

Question 16

Brushless servo-drives typically have top speeds as high as

Answer 16

9000 rpm

Question 17

Which adjustable-speed drive type motor and control provides the slowest maximum continuous torque in lb-in.?

Answer 17

DC-MC; PWM

Question 18

Which adjustable speed drive type motor and control provides the highest rpm speed range?

Answer 18

BLDC; PWM-FV

Question 19

The economies of CSI drives make them attractive in ratings

Answer 19

Above 50 HP

Question 20

A drive can be converted from a speed control to a tension control system through a

Answer 20

Torque control option

Question 21

Traction drives are best suited for applications with

Answer 21

Steady loading

Question 22

What do adjustable-speed drives change in an electric motor?

Answer 22

Output speed

Question 23

What 2 types of adjustable-speed drives are widely used in conveyor applications?

Answer 23

Mechanical and electrical

Question 24

What are ALL adjustable-speed drives capable of providing?

Answer 24

Means for stoping, Means for adjusting the output speed of the drive, Means for starting (all of the above)

Question 25

Which of the following is a typical constant-horsepower application?

Answer 25

Dough Mixer

Question 26

What type of drive regulates current rather than voltage?

Answer 26

CSI drive

Question 27

Time required to reach 50% of the final value

Answer 27

Delay time

Question 28

The motor continually searches around the desired value but never settles in.

Answer 28

Hunting

Question 29

Time required to reach first peak overshoot.

Answer 29

Peak Time

Question 30

Motor searches during a short period of time for the command signal and finally settles in.

Answer 30

Ringing

Question 31

Time required to go from 10% to 90% of the final value.

Answer 31

Rise time

Question 32

Time required to reach and stay within the allowed band of the final value.

Answer 32

Settling time