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JATC Year 3: Motor Control Final > Motor Control 3: Lesson 1 - DC Motor Control > Flashcards

Motor Control 3: Lesson 1 - DC Motor Control Flashcards

1
Q

The ______ motor can be started manually with a rheostat.
Select one:

a. AC
b. DC

A

b. DC

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2
Q

Most new or upgraded DC systems use what type of starting method?

a. contactor
b. electronic DC drive
c. rheostat

A

b. electronic DC drive

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3
Q

When starting a DC motor with a rheostat, the current at the field winding is ______ and the current at the armature is ______.

a. high / high
b. high / low
c. low / high

A

b. high / low

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4
Q

During the operation of a DC rheostat motor starter, the resistance is ______ in the field winding and ______ in the armature until the motor is brought up to full speed.

a. increased / increased
b. increased / reduced
c. reduced / increased

A

b. increased / reduced

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5
Q

Most DC motor contactors consist of ______ set(s) of contacts.

a. one
b. two
c. three

A

a. one

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6
Q

The standard coil voltage ratings for DC contactors are 12, 24, 48, 120, and ______.

a. 240 V DC
b. 277 V DC
c. 480 V DC

A

a. 240 V DC

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7
Q

DC currents stay ______ the zero axis and maintain a constant current flow to the motor.

a. above
b. at
c. below

A

a. above

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8
Q

It is important to make and break contacts as quickly as possible to extinguish the arc promptly and to extend the life of the contacts and contactor.

True or False

A

True

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9
Q

Arc chutes typically absorb ______ than 80% of the energy released during the interruption of current flow as the contacts open.

a. greater
b. less

A

a. greater

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10
Q

The magnetic ______ coil produces a magnetic field between the breaking contacts that forces the arc up, increasing the length of the arc and causing it to dissipate faster.

a. blowout
b. contactor
c. overload

A

a. blowout

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11
Q

Because solid-state drives do not use ______, energy is not wasted in the form of heat.

a. coils
b. overloads
c. resistors

A

c. resistors

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12
Q

Which section of solid-state DC drives is capable of varying the motor speed above and below the motor base speed?

a. Control section
b. Power section

A

a. Control section

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13
Q

Which section of solid-state DC drives supplies the DC voltage to the motor?

a. Control section
b. Power section

A

b. Power section

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14
Q

How many DC motor wiring configurations are there?

a. 1
b. 2
c. 3

A

c. 3

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15
Q

Control of the armature or field voltage is used to control the speed.

True or False

A

True

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16
Q

Tachometer and encoder are two devices that are used to monitor the ______ of the motor.

a. current
b. speed
c. torque

A

b. speed

17
Q

The ______ section of a DC drive is also capable of controlling the motor direction.

a. control
b. power

A

a. control

18
Q

DC drives use a ______ method to smoothly accelerate and decelerate the motor.

a. reduced voltage
b. ramping
c. soft start

A

b. ramping

19
Q

Ramping works well for ______ loads.

a. large
b. small

A

b. small

20
Q

When stopping heavy loads without a brake, the large inertia of the load continues to rotate the motor after the ramp down voltage has stopped.

True or False

A

True

21
Q

Dynamic braking is a motor braking technique where the motor is operated as a ______ after the main power is removed.

a. capacitor
b. DC generator
c. mechanical brake

A

b. DC generator

22
Q

The braking resistor is connected to the ______ during dynamic breaking.

a. armature leads
b. field winding leads

A

a. armature leads

23
Q

Which braking method decelerates the motor faster than the other?

a. Dynamic braking
b. Regenerative braking

A

b. Regenerative braking

24
Q

Regenerative braking returns the regenerated power of a DC motor back to the ______.

a. capacitor
b. DC generator
c. power source

A

c. power source

25
Q

When performing maintenance with the motor off, a visual inspection should include a check for excess dirt accumulation, burns, or damaged starter components.

True or False

A

True

26
Q

To check if a rheostat is working properly, test each tap for a different resistor value using a DMM.

True or False

A

True

27
Q

Most DC motor drives detect and display common circuit and/or fault numbers to help identify problem conditions.

True or False

A

True

JATC Year 3: Motor Control Final (12 decks)

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