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Exam prep > Principles of Electricity > Flashcards

Principles of Electricity Flashcards

1
Q

In a _____, the voltage is stepped up on the secondary side which causes the current to drop.

A

Step Up Transformer

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2
Q

What is the benefit of higher power factor?

A

Lower operating cost

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3
Q

How are the leads arranged in a wye or star connection?

A

Three are connected together, and three are brought out to connect to the load

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4
Q

The line currents of a delta-connected generator are _____

A

Equal in value and 120 degrees apart

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5
Q

Clamp on ammeters measure current by measuring what?

A

The strength of the flux field around a conductor

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6
Q

What needs to happen in an AC generator before it can produce voltage?

A

The rotor must be excited

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7
Q

What is a rotor?

A

The rotating part of an AC generator

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8
Q

Why is three phase power preferred to single phase?

A

Less copper is required to deliver the same amount of power

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9
Q

When analyzing a parallel inductive-resistive-capacitive circuit, what is assumed?

A

Each branch is purely inductive, capacitive, or resistive

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10
Q

_____ must be known in order to calculate inductive resistance

A

Frequency

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11
Q

In a parallel-Inductive-capacitive circuit, the power factor is equal to _____

A

The true power divided by the apparent power

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12
Q

In a series-inductive-capacitive circuit, inductive and capacitive voltages are not _____

A

In phase with each other

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13
Q

In a series AC circuit, _____ and _____ are in phase with each other

A

Source voltage and line current

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14
Q

What is the standard power source line frequency in the United States?

A

60Hz

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15
Q

What must be known in an inductive AC circuit to find current?

A

The source voltage

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16
Q

What is CEMF and how is it created?

A

Counter electomotive force, created by a change in current caused by a constantly changing magnetic field

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17
Q

What is a pure inductive circuit?

A

An AC circuit with no resistance

18
Q

What is considered low power factor?

A

Any power factor less than 90%

19
Q

What is the difference between true power and reactive power?

A

True power is supplied to a resistive load to do work

20
Q

_____ circuits are frequently used in electronics applications

A

Series/Parallel Resistive-Capacitive circuits

21
Q

When a circuit is _____, the current lags the source voltage.

A

Inductive

22
Q

Increasing the frequency in a parralel inductive-resistive-capacitive circuit causes current flow to decrease in the _____ branch

A

Inductive

23
Q

Inductive capacitive branches of a circuit _____ have resistance

A

Do

24
Q

Using Ohm’s Law, current is often reduce to _____ in order to calculate total line current.

A

its vertical and horizontal components

25
Q

_____ is the opposition to current flow by a capacitor

A

Capacitive Resistance

26
Q

When analyzing a series circuit, _____ is used as a reference for all other circuit parameters

A

Current

27
Q

_____ is the same across all branch circuits of a parallel inductive-resistive-capacitive circuit

A

Voltage

28
Q

Series/parallel inductive-resistive-capacitive circuitsare usually analyzed to calculate _____, _____, _____, but not _____

A

Power Factor, Circuit Power, Total Circuit Current, Frequency

29
Q

What is Eddy Current Loss?

A

Power loss in a transformer or motor due to induced current in surrounding metal structures

30
Q

What is an Isolation Transformer?

A

A transformer with equal primary and secondary winding used to separate the source from the load

31
Q

What is a swamping resistor?

A

A resistor used to suppress the high inductive kick of an exciter current

32
Q

Three-phase power system use three individual _____ to transmit power

A

Conductors

33
Q

_____ measure current by measuring the strength of the current around a single conductor

A

Clamp-On Ammeters

34
Q

A _____ is a test instrument used to measure true power in a circuit

A

Wattmeter

35
Q

A _____ is not an example of an inductive load

A

Motor Under Full Load

36
Q

What is plugging?

A

Switching polarities in a motor to brake

37
Q

Frequency changes only directly effect _____, the rest of the parameters are indirectly affected.

A

Capacitive Reactance

38
Q

In a pure capacitive circuit, the current _____ the source voltage by 90 degrees

A

Leads

39
Q

In a series-capacitive circuit _____ is the same at all points for all components

A

Current

40
Q

What is the common method for correcting power factor?

A

Connecting capacitors across the load

41
Q

What is Power Factor?

A

The ratio of true power to apparent power

42
Q

True power is measured in _____

A

Watts

Exam prep (4 decks)

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