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Electrical Grid 1 > Chapter 6 > Flashcards

Chapter 6 Flashcards

AC Generation

1
Q

One fundamental law of physics states _____________

A

That energy can be converted but it cannot be created or destroyed.

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2
Q

In an AC generator, what is some form of energy converted into?

A

Mechanical motion

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3
Q

How is mechanical motion used?

A

To rotate a machine that converts motion into electrical energy.

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4
Q

What is the last conversion?

A

Heat or motion.

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5
Q

What are examples of heat energy?

A
  • Light bulbs
  • Toasters
  • Electric ovens
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6
Q

How is energy in motion often seen?

A

In electrical motors.

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7
Q

What does the law of charges state?

A
  • Like charges repel

- Opposite charges attract

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8
Q

How does converting motion to energy work?

A

If a conductor is passed near a magnet, current will flow if a complete circuit exists. If the negative pole of a magnet is passed near a conductor, all of the negatively charged electrons will move away creating flow. If the magnet is reversed, the positive pole will attract the negatively charged electrons back toward the magnet.

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9
Q

How does the machine that converts mechanical motion into electrical energy work?

A

It spins a magnet inside of a coil of wire. The spinning magnet causes the opposite poles to alternately pass near a conductor.

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10
Q

In AC circuits what do the terms positive and negative refer to?

A

The direction of current flow in a conductor.

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11
Q

What is polarity?

A
  • Voltage pushes electrons away it is +

- Voltage brig electrons in, it is -

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12
Q

What are the three factors that determine the strength of voltage to be produced?

A
  • The number of turns in the coil of wire
  • The strength of the magnetic field
  • The speed at which the magnetic lines of flux pass through the coil
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13
Q

What needs to happen for a generator to produce one volt?

A

A single conductor must pass through 100,000,000 lines of flux in one second.

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14
Q

What happens if we continue to coil the conductor?

A

Higher voltage is achieved even though the speed and strength of the magnetic field remain constant.

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15
Q

What is a sine wave?

A

A graphical representation of what is happening to voltage in an AC circuit over a period of time.

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16
Q

What happens when a generator has rotated 90*?

A

The voltage has reached its maximum or peak positive value. The coil is at its closest point to the negative pole.

17
Q

What happens when a generator has rotated 180*?

A

The voltage has decreased to zero. The coil is midpoint between positive and negative poles of the magnet. No voltage is being produced.

18
Q

What happens when a generator has rotated 270*?

A

The voltage has increased to its maximum or peak negative value. The coil is at its closest point to the positive pole.

19
Q

What is the only difference between a positive and negative voltage?

A

The direction of electron flow.

20
Q

What happens when a generator has rotated 360*?

A

The voltage has returned to zero. The coil is at its original starting point. This is one complete rotation of a generator. One rotation is also referred to as a cycle.

21
Q

What is the number of times that a generator rotates in one second known as?

A

Frequency and is measured in cycles per second or Hertz (Hz)

22
Q

What does frequency mean?

A

Frequency is the number of times a generator rotates in one second, and is measured in cycle per second or Hertz (Hz)

23
Q

What is the frequency of power in the US and Canada?

A

60 Hz

24
Q

How are sine waves given their name?

A

The voltage at any point along the waveform is equal to the maximum voltage times the sine of the angle of rotation.

25
Q

What is the formula for sine waves?

A

E(inst) = E(max) x Sine /_

26
Q

What is E(inst)?

A

The instantaneous voltage, or the voltage at any point on the waveform.

27
Q

What is E(max)?

A

The maximum, or peak voltage.

28
Q

What is Sine/_?

A

The sine of the angle of rotation.

29
Q

How many times does voltage fall to zero per cycle?

A

3x

30
Q

The voltage produced by a DC source is one ___value.

A

Continuous

31
Q

What is RMS?

A

Effective Value. Root Mean Square. Same amount of power as a LIKE value of DC Voltage.

32
Q

What is the equation to find RMS?

A

RMS = 0.707 x Peak

33
Q

What is the equation to find peak?

A

Peak = 1.414 x RMS

34
Q

What is the type of load in a DC Circuit?

A

Resistive

35
Q

What are the three types of loads in an AC Circuit?

A

Resistive, Inductive, and Capacitive

36
Q

What does the type of load in a circuit determine?

A

The relationship between voltage and current.

37
Q

What does it mean to be “in phase?”

A

The voltage and current rise and drop at the same time.

38
Q

What does “out of phase” mean?

A

The current and voltage rise and fall at different times.

Electrical Grid 1 (10 decks)

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