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Motor control > Review sheets > Flashcards

Review sheets Flashcards

1
Q

The rated or nameplate current of a motor?

A

full load current

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2
Q

the current drawn when a motor is stalled?

A

locked rotor current

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3
Q

another name for across-the-line starting?

A

full motor voltage start

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4
Q

a method of starting a motor with a lower value than rated line voltage?

A

reduced voltage start

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5
Q

a magnetic starter and fused safety switch within the same enclosure?

A

combination starter

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6
Q

the device in a magnetic starter which helps reduce contact chatter

A

shading coil

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7
Q

the part of the circuit associated with the auxiliary seal-in contact?

A

control circuit

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8
Q

a diagram which shows the general layout of the components and the interconnections?

A

wiring diagram

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9
Q

the part of a magnetic starter circuit which prevents automatic restarting after a power failure?

A

seal in contact

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10
Q

A shading coil in a magnetic starter is intended to:

a) maintain the starter in the closed position
b) produce faster response time
c) reduce arcing
d) reduce chatter

A

d) reduce chatter

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11
Q

Overload protection of a motor is provided by:

a) capacitors
b) bi-metal units and heaters
c) control transformers
d) breakers or fuses

A

b) bi-metal units and heaters

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12
Q

A magnetic blow-out coil:

a) reduces chattering of a starter
b) provides overload protection
c) limits motor starting current
d) aids in extinguishing the arc between contacts

A

d) aids in extinguishing the arc between contacts

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13
Q

When used, the holding/maintaining/ seal-in contact of a magnetic starter is:

a) in series with the stop button
b) in parallel with the stop button
c) connected across the holding coil
d) in series with the start button

A

a) in series with the stop button

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14
Q

In the case of a power failure, when a motor will not re-start after the voltage is re-established, is referred to as:

a) low voltage protection
b) line voltage starting
c) low voltage release
d) reduced voltage starting

A

a) low voltage protection

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15
Q

the purpose of an electrical interlock in a forward/reverse motor control circuit is:

a) to maintain the coil circuit
b) to prevent more than one starter a time from being energized
c) to provide plugging to stop the motor quickly
d) for activating indicating or pilot lights

A

b) to prevent more than one starter at a time from being energized

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16
Q

The control circuit, in across the line starters or forward/reversing starters, for 3Ø induction motors are :

a) 3Ø
b) 2Ø
c) 1Ø

A

c) 1Ø

17
Q

A knife switch should be open quickly to:

a) reduce arcing at the contacts
b) save the operator time
c) prevent voltage surges in the circuit
d) be certain that the circuit voltage is completely interrupted

A

a) reduce arcing at the contacts

18
Q

A rheostat is generally described as a:

a) fixed voltage divider
b) current controlling device connected in series with the load.
c) voltage controlling device
d) variable inductance

A

b) current controlling device connected in series with the load

19
Q

Limit switches are usually used to control:

a) speed
b) torque
c) current
d) travel

A

d) travel

20
Q

Any control device which opens a circuit on failure of voltage but does not prevent re-establishment when the voltage returns to normal operating value is known as:

a) high voltage release
b) low voltage release
c) low voltage protection
d) high voltage protection

A

low voltage release

21
Q

A motor operating a band saw, a planer or similar equipment, which may constitute a hazard, must be controlled by a device that provides:

a) low voltage release
b) low voltage protection
c) neither a or b
d) either a or b

A

b) low voltage protection

22
Q

Which of the following is essential in a magnetic motor starter control circuit, if then start button is momentary contact type:

a) mechanical interlock
b) holding contact
c) a low impedance solenoid
d) a time delay relay

A

b) holding contact

23
Q

What is the difference between “2-wire control” and “3-wire control”?

A

two wire is for automatic operation

three wire includes manual devices such as push buttons

24
Q

What is the difference between a “wiring diagram” and a “schematic diagram”

A

schematic is a line diagram using symbols to identify operation of circuit

Wiring is an inter. connection diagram illustrating layout of components

25
Q

An overload device disconnects the motor from the supply by:

a) burning out a fusible link in the overload heater
b) heating a device which causes a set of contacts to open
c) tripping the overcurrent protection
d) causing a set of contacts to close

A

b) heating a device which causes a set of contacts to open

26
Q

The purpose of the overload protection is to protect the conductors, starter, and motor from:

a) short circuits
b) ground faults
c) overheating
d) undercurrent

A

c) overheating

27
Q

The type of circuit that will not allow a motor to automatically restart after a loss of voltage is called:

a) low voltage release
b) low voltage lock-out
c) under voltage reset
d) low voltage protection

A

d) low voltage protection

28
Q

A magnetic blowout coil:

a) prevents chattering on a contactor
b) provides overload protection
c) limits the motor starting current
d) helps extinguish the arc between contacts

A

d) helps extinguish the arc between contacts

29
Q

The two basic parts of a thermal overload are:

a) the heater and the electromagnetic coil
b) the heater and the normally closed contact
c) the coil and the normally closed contact
d) the coil and the normally open contact

A

b) the heater and the normally closed contact

30
Q

The overload relay contacts are usually wired in the control circuit:

a) between the stop and start buttons
b) between the stop button and the magnetic coil
c) between the start button and the magnetic coil
d) between the magnetic coil and line 2

A

d) between the magnetic coil and line 2

31
Q

Magnetic starters use shading coils to:

a) prevent arcing at the contacts
b) reduce contact chatter
c) cool the armature surface of the electromagnet
d) reduce the coil current of the starter

A

b) reduce contact chatter

32
Q

limit switches are most commonly used in motor control to limit:

a) over speed
b) over pressure
c) over current
d) over travel

A

d) over travel

33
Q

Magnetic starters without overload relay devices are referred to as:

a) contactors
b) control relays
c) clappers
d) magnetic blowouts

A

a) contactors

34
Q

The terms “diaphram” , “bourden tube”, “bellows”, and “piston” are associated with types of:

a) pressure switches
b) flow switches
c) limit switches
d) solenoids

A

a) pressure switches

Motor control (5 decks)

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