motor principle Flashcards

1
Q

what four factors determine the magnitude of induced emf?

A
  1. the flux density (B)
  2. the length (l) of the conductor actually cutting through the magnetic field.
  3. the rate of motion or velocity of the conductor through the magnetic field.
  4. the angle at which the conductor cuts through the magnetic field.
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2
Q

At what angle is a conductor cutting through the magnetic field produces the maximum emf?

A

a conductor produces the maximum emf when it’s cutting at right angle through the magnetic field.

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3
Q

At what angle is a conductor cutting through the magnetic field produces no emf?

A

when the conductor is in parallel with the magnetic field.

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4
Q

what three factor can increase the magnitude of induced voltage and current in a solenoid?

A
  1. using a stronger magnet and therefore an increased flux density
  2. increasing the velocity of the magnet passing through the solenoid.
  3. increasing the number of turns of the solenoid, as the this increases the length of the conductor being cut by the magnetic field.
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5
Q

whats the difference between permanent magnet machines and wound machines?

A

Permanent-magnet dc motors use conventional armatures and permanent magnets rather than winding in the field section.

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6
Q

what applications is permanent-magnet dc motors used in?

A
vehicles 
printers
battery-operated devices
domestic appliance 
conveyors and elevators
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7
Q

hows does a dc motor work?

A

dc motor uses electric energy to do mechanical work.

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8
Q

names the parts of a dc motor?

A

the motor has a stator which is a stationary magnetic field (can either be permanent or electro-magnet). it then has armature which consist of wound core is the rotating magnetic field, shaft. the brushes and brush holders and lead connection are in the commutator.

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9
Q

whats the purpose of inter-poles in a dc motor.

A

Interpoles are designed in DC motors to overcome the effects of the armature reactance and the self-induction of the machine.
Inter-poles are wired in series with the armature.
Any changes in the armature current due to armature reactance, loading, or self-inductance passes through the inter-pole windings.

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