Motor Controls Final Oh No

Front 1

What do OLs do?

Back 1

Protect the motor from being overloaded

Front 2

What happens when a motor is overloaded?

Back 2

It heats up and melts the coils together

Front 3

What types of overloads are there?

Back 3

Thermal and magnetic

Front 4

What are the types of thermal OLs?

Back 4

Bi-metal, Eutectic

Front 5

What is a bi-metal OL?

Back 5

Two metals with different thermal properties are joined. When heated, they expand and contract at different rates, which causes the piece to bend. This causes the spring loaded mechanism of the OL to be released, tripping the OL contact.

Front 6

What does the OL prevent from overheating?

Back 6

The stator.

Front 7

If the OL keeps tripping, what might your problem be?

Back 7

Mechanical.

Front 8

What does a eutectic OL use to function?

Back 8

Low metal temperature solder.

Front 9

How does a Eutectic OL work?

Back 9

A tube with eutectic alloy is attached to a gear. The gear is mechanically connected to the spring loaded portion of the OL, while the end with the eutectic alloy is attached to the motor circuit. If the motor heats up, this melts the eutectic alloy, which allows the gear to move and trips the overload.

Front 10

When the OL trips, what does it disconnect?

Back 10

The neutral.

Front 11

How does no/low voltage release reset?

Back 11

Automatically

Front 12

How does low/no voltage protection reset?

Back 12

Manually.

Front 13

What's the difference between no/low voltage release and no/low voltage protection?

Back 13

Release is auto reset, protection is manual reset.

Front 14

How do low/no voltage release and protection work?

Back 14

Contacts release when no voltage is present.

Front 15

What are solid state OLs?

Back 15

Sensing circuits that monitor the current.

Front 16

Which is more accurate, a solid state OL or a thermal OL?

Back 16

A solid state OL.

Front 17

What has a fine current adjustment?

Back 17

Solid state

Front 18

What do phase monitors do?

Back 18

Disconnect all phases when there is voltage loss on one or multiple phases.

Front 19

What does a phase monitor prevent?

Back 19

Single phasing.

Front 20

When the overloads are not in the same location of the starter, what becomes a factor?

Back 20

Ambient temperature.

Front 21

When does ambient temperature become a factor to OLs?

Back 21

When they aren't in the same location as the starter.

Front 22

What is used to accommodate ambient temperature?

Back 22

Ambient-compensated overloads.

Front 23

What does trip free mean?

Back 23

That there isn't a way to hold down the reset button and prevent the OL from tripping

Front 24

What should all OLs be?

Back 24

Trip free.

Front 25

What do OLs not protect against?

Back 25

Short circuits.

Front 26

Do OLs protect against short circuits?

Back 26

No.

Front 27

What do OLs protect?

Back 27

The motor.

Front 28

What do fuses and breakers protect against?

Back 28

Short circuits.

Front 29

What do GFCIs protect against?

Back 29

Shocks.

Front 30

What is a motor starter?

Back 30

A contractor with overloads.

Front 31

What is a contactor?

Back 31

A relay rated for over twenty amps.

Front 32

What are motor starters classified by?

Back 32

NEMA.

Front 33

A larger size of motor, rated in horsepower, means what for the NEMA rating?

Back 33

It is larger as well.

Front 34

What do NEMA ratings start at?

Back 34

00

Front 35

What is IEC based on?

Back 35

Current.

Front 36

What do motor starters contain or provide?

Back 36

They contain or provide mechanical connection for auxiliary contacts, both NO and NC.

Front 37

What are the NO and NC auxiliary contacts on motor starters used for?

Back 37

To seal in the control circuit and to provide an interlock to avoid shorting out two of the phases.

Front 38

What does an interlock do?

Back 38

Prevents certain components from operating at the same time.

Front 39

What's special about magnetic motor starters?

Back 39

Contacts are closed by an electromagnetic solenoid

Front 40

Two sets of contacts on a magnetic motor starter means what?

Back 40

Single phase

Front 41

Three sets of contacts on a magnetic motor starter means what?

Back 41

Three phase.

Front 42

What types of motor starter operation are there?

Back 42

Manual and magnetic.

Front 43

What are some facts about full voltage motor starters?

Back 43

It's is most common.

Connects motor directly to line voltage

Simple

Low maintenance

Front 44

What sort of motor starter do we have in class?

Back 44

Full voltage.

Front 45

What is full voltage also known as?

Back 45

Across the line.

Front 46

When is a combination motor starter used?

Back 46

When you don't have that much time to mess with it.

Front 47

What are some characteristics of a combination motor starter?

Back 47

Everything is kept in one enclosure, it just requires wiring.

Front 48

What is a reversing motor starter?

Back 48

Two contractors of equal NEMA size that are both protected by one OL.

Front 49

On reversing motor starters, what must you do?

Back 49

Properly connect the three motor phases.

Front 50

Do we have a reversing motor starter in lab?

Back 50

Yes we do.

Front 51

What do reversing motor starters come with?

Back 51

A mechanical interlock or lock out to prevent both from energizing.

Front 52

What would happen if both of a reversing motor starter's contacts were energized at the same time?

Back 52

A direct short, and an arc flash!!

Front 53

What does a multi-speed motor starter do?

Back 53

Changes the number of poles used in the stator winding.

Front 54

What is a practical amount of speeds on a multi speed motor?

Back 54

Three.

Front 55

In multi speed motor starters, what does each speed need?

Back 55

Separate overload contacts.

Front 56

Why do multi speed motor starters need separate overload contacts for each speed?

Back 56

Because the different speeds have a different current and different horse power.

Front 57

What do reduced voltage starters do?

Back 57

Lower the voltage, current, motor speed, torque of the motor.

Front 58

What is an autotransformer?

Back 58

Compensator

Front 59

In what way does an autotransformer relate to the windings?

Back 59

The windings have multiple taps. 50%, 65%, and 80%.

Front 60

What is an open transition?

Back 60

The moment the start contactor disengages and the run contactor is engaged. It's the time between the transition.

Front 61

What is a closed transition?

Back 61

It works like an open transition but uses an extra motor starter to keep the motor engaged during the transition from start to run.

Front 62

What does a closed transition provide?

Back 62

Less voltage spikes.

Front 63

Which is preferable, open transition or closed transition?

Back 63

Closed transition. Because it doesn't have voltage spikes.

Front 64

What is a primary resistor?

Back 64

A wat to reduce the voltage going to the motor.

Front 65

Can multiple resistors be used on Motors to provide multiple speeds?

Back 65

Yes.

Front 66

What does more resistance equal in terms of voltage and speed?

Back 66

Lower provided voltage, and therefore slower speed.

Front 67

What are the two types of part winding?

Back 67

Two step and three step.

Front 68

What are the two steps of two step part winding?

Back 68

1. Start coils are energized with full voltage. 2. Run coils are connected in parallel.

Front 69

What are the three steps of three step part winding?

Back 69

1. Resistors in series with start coil.

2. After time delay, resistors are bypassed and full voltage to start coils.

3. After time delay run coils are connected in parallel.

Front 70

What does DC injection do?

Back 70

Brings the motor to a stop.

Front 71

What are some features of a solid state motor?

Back 71

Smaller in size, cheaper, more popular, programmable, ramp up, ramp down, smoother start.

Front 72

What is ramp up also known as?

Back 72

Soft start.

Front 73

On figure three, where does the black lead go?

Back 73

X3

Front 74

On figure three, what voltage is the motor part of the circuit?

Back 74

208 phase to phase.

Front 75

What is the voltage of the control side on figure three?

Back 75

120.