Motors And Controls Final Exam Flashcards
Are AC power source motors induction or conduction types?
(AC) has brushes
induction
Are DC power source motors induction or conduction types?
Conduction
Which electrical motor runs on either AC or DC?
Universal
If the electrical current through the coil is reversed, what would happen to the produced magnetic field?
Reverse
What are two types of motor operation on a magnetic motor starter can provide?
Start
Stop
What advantages does a single-phase motor have over a three-phase motor?
Can be used where 3-phase can’t
Which type of electric motors require start windings?
Single phase induction motor
What is the advantages of installing the control circuit as a class defined power source circuit if possible?
Control circuit runs on a lower volatage for safety reasons
How is a single-phase motor reversed?
Reverse start or the auxiliary, but not both
How is a three-phase motor reversed?
Change any 3-phase comnection to the start winding
What two functions do capacitors perform in a single-phase motors?
Start
Run
Condition where the magnetic poles of the run winding will alternate between north and south at sychonous speed of the power supply but does not product rotation?
Locked rotor
This is used to determince the amount of mechanicl work that can be performed?
Torque
This is a measurement used to determine how much work is heing completed in a certain amount of time?
Power
List the three types of relays that may be used to disconnect the start winding of single-phase motors when a centrifugal switch on the rotor shaft cannot br used?
Current relay
Potential relay
Solid state relay
What components does a single-phase motor require that a three-phase motor does not?
Start and run capacitors
Is the start winding a lower or hogher resistance than the main winding?
Higher
Is the start winding a smaller or bigger gauge than thr main winding?
Smaller
What are two purposes for run capacitors in the auxiliary winding?
Maintaining torque
Create a phase-shift between auxiliary winding
What is the main limitation of shaded-pole motors?
Low starting torque and low efficiency
Single phase induction motor both start and run reversed, what would happen to rotation?
Nothing
Which electrical property is responsible for creatig magnetic flux?
Induction
Why are induction motors so popular?
More reliable at a lower cost
The terminals at the bottom of a motor starter are labeled what?
2 and 3
Which circuit conductod gets landed on the top terminals of a motor stater?
L1, L2, and L3
The overload contacts are wired in which circuit?
Between the starter and neutral leg of the control circuit
Why does the moving contact of a relay sweep across the face of rhe stationary contact?
Mechanically clean
Which unit has both controls circuit?
The contactor
FLA ?
Full loaded amps
LRA?
Locked rotor amps
List two instances when a motor will be exposed to LRA?
at startup
Low starting toque
When reversing a single-phase motor what terminals are switched?
T5 and T8
What are three winding configurations for DC motors?
Series
Shunt
Compound
This winding has small number of turns?
Series
This winding uses a strong flux to keep the armature locked in and requires the field to be powered first before the armature
Shunt winding
DC motor that uses both series and shunt winding?
Compound winding
What is nominal voltage?
Designed or figuration voltage