Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Motors > Motor Starters > Flashcards

Motor Starters Flashcards

1
Q

Motor starters can be of two main types what are they

A

Across the line {FVS}
Reduced voltage starters
(Reduces V at start, full V for run)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the most common starting method?

A

Full voltage/ across the line start

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the terminal marking for a part winding starter

A

T1-T3 and T7-T9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

List the terminal marking on a wye-delta starter.

A

T1-T6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the purpose of a reduced voltage starter

A

To reduce the inrush current at start

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List two starting modes that are common on electric soft starters

A

Ramp start

And current limiting start

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

True or false
the load to a rotary converter must not be connected until the converter reaches its rated speed and is supplying 3 phase power

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

True or false

Static phase converter can supply more than one load

A

False

Can only supply one load at a time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

True or false

A rotary phase converter can supply more than one load

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Can a static phase converter supply power to a single three phase motor?

A

Yes it can

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

True or false

Static phase converts are more balanced than Rotary phase converters

A

False

Rotary phase converters are the balanced of the two types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

True or false

Single phase motors are available above 15 hp are often found above 5hp

A

False

Not available above 15 hp and rarely found above 5hp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

By how much does a wye/delta starter reduce the starting line current, compared to a full voltage start?

A

Starting line current would 1/3 smaller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

True or false

Starting torque is reduced by 1/3 of what it would be if the motor was started at full voltage.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The overloads of a wye delta starter are based on the line current.
True or false?

A

False they are based on the phase current (57.7% of the line current)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A continuity test on a dual voltage delta motor would show how many groups of leads?

A

3 groups of 3 leads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

True or false

Dual voltage motors reduce stocking costs for manufacturers and wholesalers

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

True or false

A continuity test on a dual voltage wye motor would reveal 1 group of three leads and 3 groups of two leads.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

A single voltage wye start delta run motor is required for wye/delta starting
True or false

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

A continuity test on a single voltage six lead motor would reveal what?

A

3 groups of two leads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the three basic functions of a vfd?

A

Rectifier
Filter
Inverter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does the rectifier do?

A

Turns ac supply into dc and supplies the dc voltage to the dc link

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the filter do?

A

Provides a clean and smooth DC source for the inverter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does an inverter do?

A

Converts the DC to an AC voltage which is voltage a frequency controlled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

True or false

Changing the timing of pulse cycles will change the output frequency when using pulse width modulation.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Will changing the width of the pulses in PWM change the output voltage?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the Igbt?

A

It’s is a high current fast switching voltage controlled device. In charge of the on/off switching of the pulse.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

True or false

I order to not exceed the fla rating of the motor, the motor voltage (E) must be lowered as frequency is lowered

A

True

V/Hz ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What must a nameplate state to indicate a motor is compatible with a vfd

A

Inverter duty

30
Q

What is open loop feedback

A

It means the vfd runs according to preset values set within the programming

31
Q

Describe closed loop feedback

A

On top of running a t preset values. The vfd relies on feedback and responds to sensing devices accordingly

32
Q

What are the four main pieces of info needed from motor in order to pick a starter

A

Hp rating
Voltage
FLA
Service Factor

33
Q

What is a linear load and name an example

A

Impedance stays the same when voltage and current vary

A résister is linear

34
Q

What is a non linear load and name an example

A

When the Z changes as V changes

Examples are motors, VFD’S, electronic ballasts, cpu power supplies

35
Q

Name 3 problems that occur from harmonic currents

A

Excessive neutral current
Additional hysteresis losses
Harm to the motor connected to vfd

36
Q

How are harmonics reduced?

A

Line reactors installed on the line side of the vfd
Harmonic filters
Harmonic réduction built in to vfd

37
Q

What do vfd cables require to prevent RFI (radio frequency interference)

A

Shielding or continuous metal armour

38
Q

How far should vfd cables be from control and signal cables? And if they cross paths, at what angle must they do so

A

300 mm

90 degrees

39
Q

What does the carries frequency of a vfd do

A

Determine the actual number of pulsée the drive produces

40
Q

A vfd changes the speed of a motor by changing what two parameters

A

Voltage and frequency

41
Q

What does the V/hz ratio help determine

A

The motor current

42
Q

What is torque boost

A

V/hz is programmed to provide higher voltage which produces higher current and torque at lower frequency operation

43
Q

What are the two types of full voltage starters?

A

Magnetic and manual

44
Q

Which starter is also a disconnect means

A

Manual starter

45
Q

Name the terminals of a part winding motor

A

T1 - T3

T7 - T9

46
Q

Describe briefly how a part winding starter works

A

Full voltage is applied to the first group of windings

After a preset time, for voltage is applied to the second group of windings so that both groups are energized

47
Q

A time delay on energization is also known as

A

On delay

48
Q

A time delay on D energize Asian is also known as

A

Off delay

49
Q

What does it mean when contacts are labeled TO or TC

A

Timed to open

Timed to close

50
Q

What is the most common starting method

A

Across the line

Full voltage start

51
Q

The overload setting of a wye delta start are based on what percentage of fla

A

57.7%

52
Q

What is an Electronic soft starter

A

Reduces starter currents with electronics

53
Q

Describe ramp starting

A

Starting current is increased at a constant rate

54
Q

Describe current limit starting

A

Restricts starting current to a maximum

55
Q

Describe kickstarting

A

Initial current surge for hard to start loads

56
Q

Which load is harder to start, variable torque or constant torque

A

Constant torque

57
Q

What are the two types of phase converters

A

Rotary and static

58
Q

What does a basic phase converter do

A

Convert single phase power to three phase power

59
Q

Name a few places where you could find phase converters

A

Farms, small industrial plants, woodworking shops, metal fabrication shops

60
Q

What are the advantages of fractional horsepower single phase motors

A

They are cheaper and more common than three phase

61
Q

What are the advantages of three phase motors

A

More efficient, smaller, quieter, simpler

Larger horsepower are cheaper and more common

62
Q

Briefly describe how a rotary phase converter works

A

Induction motor generator and capacitors help create a third phase. This third phase along with the original two are put together to create three phase power roughly 120° apart

63
Q

True or false a rotary phase converter can supply only a single motor

A

False a rotary phase converter can supply several motors

64
Q

What are the two horse power ratings for a rotary phase converter

A

Maximum starting horse power equals largest motor

Maximum running horse power equals all motors added together

65
Q

True or false. A static phase converter can supply several motors

A

False. A static phase converter can supply only a single motor

66
Q

Which phase converter has a more balanced out put

A

Rotary phase converter’s are more balanced

67
Q

True or false. Static phase converter’s are cheaper than Rotary phase converters

A

True. Static phase converters don’t include an induction motor generator

68
Q

What are the groupings of leads of a nine lead Delta motor

A

Three groups of three leads

69
Q

What are the groupings of leads of a nine lead wye motor

A

One group of three leads And three groups of two leads

70
Q

Which motor has a group of three leads that has eight ohms between them

A

A dual voltage nine Lead wye motor

Motors (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions