Alternators & Generators Flashcards

1
Q

Define a Generator:

A

A rotating electrical machine that converts mechanical energy into electrical energy. Rated by kilowatts (or megawatts) of power that they can deliver at rated voltage and speed without overheating.

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2
Q

Define a Dynamo:

A

A rotating electrical machine that converts mechanical energy into electrical energy OR electrical energy into mechanical energy. An electrical dynamo COULD function as a dc generator or as a dc motor.

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3
Q

What is an alternator also called?

A

A synchronous generator.

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4
Q

An alternator creates alternating current when being rotated by a mechanical means. T or F?

A

True.

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5
Q

A motor is a rotating electrical machine that converts electrical energy into mechanical energy. T or F?

A

True

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6
Q

What is the role of a the field windings?

A

To create magnetic flux

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7
Q

Where are the armature windings located on a traditional dc dynamo?

A

On the rotor

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8
Q

The field windings of ac AC alternator or synchronous motor may be connected to an external circuit by connecting the coil terminals to what?

A

Slip Rings - two continuous and insulated rings mounted on shaft. Rotate with the coil and shaft.

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9
Q

What are commutators also called?

A

Split Rings

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10
Q

Brushes in an alternator are the electrical connection between the field windings and an external circuit. T or F?

A

True.

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11
Q

Electromagnetic induction is the production of a voltage in a conductor because of relative motion between the conductor and a magnetic field. T or F?

A

True

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12
Q

The usual means of controlling generated voltage is to vary the field intensity by changing the amount if current in the field winding. How is this achieved?

A

With a variable resistor, aka a Rheostat placed in series with the field winding.

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13
Q

Even if there is no field current, the core of a generator will typically remain slightly magnetized. This residual magnetism is due to what?

A

The retentivity of the core material.

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14
Q

Name the four things that affect the amount of voltage produced by electromagnetic induction in a generator.

A
  • the flux density or magnetic field intensity
  • the relative speed of the conductor to the field
  • the length of conductor exposed to the field (which is effected by the number of turns)
  • the angle at which the conductor cuts the lines of force
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15
Q

Motor or generators must never be overloaded even for a brief time. T or F?

A

False. Most motors or generators can be overloaded for a brief time.

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16
Q

By increasing the number of armature coils and commutator bars, the generator will produce a smoother output waveform. T or F?

A

True

17
Q

When the armature loop of an ac generator is at 180 degrees, what is the value of the induced voltage?

A

The value is zero