Motor Starters

Question 1

What are the 2 parts of a magnetic motor started

Answer 1

Contactor and overload device

Question 2

Do overload devices sense current or voltage

Answer 2

Current

Question 3

What class of started come pre wired with the overload attached

Answer 3

NEMA

Question 4

What starter has exposed live terminals and must be contained in an enclosure

Answer 4

NEMA

Question 5

What are the 7 parts of a contactor

Answer 5

Stationary contact, moveable contact, pressure springs, operating coil, stationary electro magnet, magnetic shading coil, movinv armeture

Question 6

What circuit are the power contacts in

Answer 6

Power cct

Question 7

What cct are the holding contacts in

Answer 7

Control cct

Question 8

What voltage must the operating coil be rated for

Answer 8

Control cct voltage

Question 9

What is a control transformer used for in motor starters

Answer 9

To step down supply voltage to power a extra low voltage to supply proper voltage to the operating coil

Question 10

What is the advantage to using an ELV coil in a starter

Answer 10

Less strict wiring restrictions

Question 11

What rating must contacts in a motor starter match

Answer 11

FLC OFmotor

Question 12

Do the holding contacts have to be fated as high as power contacts

Answer 12

No

Question 13

Can auxillary contacts be used for motor starting and stopping

Answer 13

No

Question 14

What do overload devices protect against

Answer 14

Overheating and damge to cct conductors and motor

Question 15

What do O/L devices monitor

Answer 15

Current

Question 16

What are the 2 ways an ac motor can be wired

Answer 16

2 wire single phase 3 wire 3 phase

Question 17

If a nameplate has a voltage rating of 115 v what is the nominal or source voltage used

Answer 17

120v

Question 18

Mechanical power output is the equivalent to what in a motor

Answer 18

Horsepower

Question 19

1 horsepower is how many watts

Answer 19

746w

Question 20

Motors draw more or less current at higher voltages

Answer 20

Less

Question 21

If your operating coil is rated lower than supply voltage what must be done

Answer 21

A transformer needs to be used to step down the voltage

Question 22

What 4 factors must be considered when selecting a nema starter

Answer 22

FLC of motor
Voltage fating of motor
HP rating of motor
Duty of motor (continuous or jogging)

Question 23

What must be considered when selecting an o/l device

Answer 23

Full load current and service factor of motor

Question 24

Can overload devices be adjusted

Answer 24

Sometimes

Question 25

What are the 3 types of magnetic motor starters

Answer 25

Full voltage/across the line Reduced voltage Reversing motor starters

Question 26

What type of starter gives full voltage right as the motor starts

Answer 26

Full voltage/ across the line

Question 27

What starter type slowly ramps up voltage as the motor starts

Answer 27

Reduced voltage

Question 28

What type of starter has 2 different contacts to swap the direction it runs

Answer 28

Reversing

Question 29

What nema terminal feeds the control cct

Answer 29

1

Question 30

Nema terminals 2&3 represent what

Answer 30

Holding contacts

Question 31

Where does terminal 2&3 represent

Answer 31

Holding contact

Question 32

What iec terminals do you attach auxilllary devices too like lights

Answer 32

A1, a2, or 13 , 14

Question 33

What is ambient temp rating of a motor

Answer 33

Temp the medium used to cool the motor

Question 34

What produces heat in a motor

Answer 34

Core losses, eddy currents, hysteresis, bearing friction, i2r losses

Question 35

Do overload devices always open under short cct

Answer 35

Not always

Question 36

What are the 2 sections if an overload relay

Answer 36

Current sensing section Current responding section

Question 37

What are the 2 main types of overload devices (principals they work in)

Answer 37

Thermal and magnetic

Question 38

What 3 thing ls must you consider when sizing an o/c for a motor

Answer 38

FLC of motor, type of o/c device/ type of motor

Question 39

What must motor o/l protection be based off

Answer 39

FLC of motor, service factor of motor

Question 40

If a motors service factor is not listed what do we take it as

Answer 40

1

Question 41

A motor has a service factor of 1.15 what do you multiply FLC by to size your O/L

Answer 41

1.25 or 125%

Question 42

If motor service factor is below 1.15 what do you multiply FLC by

Answer 42

1.15 or 115%

Question 43

If no horsepower is listed on motor what value must the fuse be able to interrupt

Answer 43

Locked rotor current

Question 44

What are the 3 sections of motor control ccts

Answer 44

Stopping, holding, starting

Question 45

If holding contacts are placed in the stop section of a cct what affect will it have on motor operation

Answer 45

Starting and running of the motor

Question 46

If holding contacts are placed in the start section of a cct what affect will it have on the motor

Answer 46

Only affect motor starting

Question 47

If contacts are added in the holding section of a cct what affect will it have o the motor

Answer 47

Running only motor can still bump

Question 48

A motor on low voltage release will restart as soon as power is restored

Answer 48

True

Question 49

In low voltage protection when power is reenergized motors auto restart

Answer 49

False