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JATC Year 3: Motor Control Final > Motor Control 3: Lesson 5 - Variable Frequency Drives > Flashcards

Motor Control 3: Lesson 5 - Variable Frequency Drives Flashcards

1
Q

Speed and ______ are two physical quantities that must be controlled in a motor drive.

a. direction
b. temperature
c. torque

A

c. torque

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2
Q

Motor control systems that control motor speed without feedback data for torque or speed are called ______ control systems.

a. closed-loop
b. open-loop

A

b. open-loop

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3
Q

Lower initial cost and easier installation are two advantages of a(n) _______ motor control system.

a. closed-loop
b. open-loop

A

b. open-loop

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4
Q

The VFD controls the speed of an AC motor by varying the ______ to the motor.

a. current
b. frequency
c. voltage

A

frequency

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5
Q

A tachometer/generator produces a feedback voltage which is directly proportional to the ______ of the motor.

a. horsepower
b. speed
c. torque

A

speed

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6
Q

A motor control system that uses a tachometer to control the speed of the motor is called a(n) ______ system.

a. closed-loop
b. open-loop

A

closed-loop

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7
Q

Drive, comparator, sensor, and amplifier are the four parts of a(n) ______ system.

a. closed-loop
b. open-loop

A

closed-loop

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8
Q

Tachometer/generators and optical encoders are two types of devices that are generally used to provide speed reference signals in a(n) ______ speed control system.

a. closed-loop
b. open-loop

A

closed-loop

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9
Q

In a closed-loop speed control system, the ______ is the desired speed selected for the motor connected to the drive.

a. feedback speed value
b. feedback summing amplifier
c. set point speed value

A

set point speed value

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10
Q

What is the term used to identify the speed change in Segment 1?

a. Constant speed
b. Speed ramp-down
c. Speed ramp-up

A

speed ramp-up

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11
Q

What is the speed in Segment 2?

a. Constant speed
b. Speed ramp-down
c. Speed ramp-up

A

constant speed

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12
Q

What is the term used to identify the speed change in Segment 3?

a. Constant speed
b. Speed ramp-down
c. Speed ramp-up

A

speed ramp-down

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13
Q

When using a VFD, a motor’s ramp-up speed can be adjusted to vary from a few seconds to more than ______.

a. 60 seconds
b. 120 seconds
c. 180 seconds

A

120 seconds

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14
Q

Which type of motor is generally less expensive and requires less maintenance?

a. AC
b. DC

A

AC

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15
Q

______ are installed on power lines feeding VFDs to lessen the effects of harmonics generated by the VFDs.

a. Line reactors
b. Load reactors

A

Line reactors

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16
Q

What DC control voltage is used to control the speed of the motor connected to the VFD?

a. 5 VDC
b. 10 VDC
c. 24 VAC

A

10 VDC

17
Q

If a worker was connecting a normally open discrete contact to the terminal block for the VFD and needed to turn the motor on and run the motor in the forward direction, to which two terminals would the worker connect the contact?

a. 02COM / 020
b. 10COM / 100
c. ACOM / A101

A

10COM / 100

18
Q

When connecting an alarm light or audible alarm to the “02” (02COM, 02C, or 020) terminals of the VFD, the alarm would be ? powered.

a. externally
b. internally

A

externally

19
Q

What type of connector is required to connect the communications cable when connecting an external personal computer to the VFD to monitor or program the device?

a. HDMI
b. RJ-11
c. RS232

A

RJ-11

20
Q

The VFD is an example of a(n) ______ control.

a. closed-loop
b. open-loop

A

b. open-loop

21
Q

How many factory default speeds are available for this VFD?

a. 2
b. 3
c. 4

A

3

22
Q

Where would the device be connected if the VFD could be converted for use in a closed-loop system by connecting an appropriate analog device that produced a 0-10 VDC output to the VFD?

a. 02COM / 020
b. 10COM / 100
c. ACOM / A101

A

ACOM / A101

23
Q

The motor, connected to the VFD, can be run in the reverse direction.

True or False

A

True

24
Q

When considering the environmental concerns of VFD installations, factory enclosures should have a(n) ______ rating appropriate to the level of protection for the installation.

a. IEC
b. NEMA
c. NFPA

A

NEMA

25
Q

The equipment manual and labels on the VFD equipment are two sources of information that should be consulted before installing a VFD.

True or False

A

True

26
Q

The ______ of a VFD establish(es) the speed, rotation direction, and stopping parameters for the motor.

a. control set points
b. factory preset parameters
c. incoming power source

A

control set points

27
Q

All VFDs are configured and programmed the same way.

True or False

A

False

28
Q

A drive-mounted programming interface, handheld programmer, external laptop computer, or other computers on a data network can be used as programming devices to configure VFDs.

True or False

A

True

29
Q

Which programming software feature monitors and displays the value of all drive and motor parameters in real time?

a. Display drive status
b. Error messages and alarms
c. Parameter updates

A

Display drive status

30
Q

Match the load characteristics that the VFD is required to deliver to each type of load.

Fans, centrifugal blowers, and centrifugal pumps -
Hoists, conveyors, mixers, and reciprocating or rotary compressors -
Wheel grinders, large driller machines, lathes, planers, and boring machines -

Choices:
- Constant Torque Loads
- Variable Torque Loads
- Constant Horsepower Loads

A

Fans - Variables
Hoists - Constant Torque
Wheel Grinders - Horsepower

31
Q

Which drive programming software feature displays drive parameters, such as voltage, current, frequency, speed, and power consumed?

a. Display drive status
b. Error messages and alarms
c. Parameter updates

A

Parameter updates

32
Q

Re-torquing is a good procedure to use to check the status of terminals that are held in place with bolts or screws.

True or False

A

False

33
Q

To begin troubleshooting a VFD, four sections of a drive circuit must be inspected: input devices, output devices, programming configuration, and VFD internal components.

True or False

A

True

34
Q

Most ______ problems are identified and corrected during startup.

a. input device
b. programming
c. VFD internal component

A

programming

35
Q

The three basic categories of tasks necessary to maintain a VFD in proper operating condition are: keep it clean, keep it dry, and keep connection tight.

True or False

A

True

JATC Year 3: Motor Control Final (12 decks)

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