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Level 3 Electrical, BCIT > Electronics 💀 > Flashcards

Electronics 💀 Flashcards

1
Q

What is the conventional current flow of the diode?

A

From anode to cathode

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2
Q

What direction is electron flow in a diode?

A

From cathode to anode

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3
Q

Which diodes operate at high frequencies?

A

Signal diodes

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4
Q

How much resistance does a diode in reverse bias have?

A

Infinite. Does not conduct

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5
Q

What voltage is measured on a reverse bias diode?

A

Source voltage

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6
Q

What is the resistance of a forward bias diode?

A

Zero

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7
Q

What is forward current rating?

A

Max RMS value that the diode can handle without damage

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8
Q

What is PIV?

A

Peak inverse voltage. Max peak voltage that the diode can safely handle

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9
Q

What is breakdown voltage?

A

Voltage passed the PIV rating. Diode will not block anymore, and will conduct very large current

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10
Q

What is the main purpose of a Zener diode?

A

Voltage regulator

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11
Q

What bias do zeners conduct in?

A

Forward

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12
Q

What happens to a Zener in reverse bias?

A

Blocks until breakdown voltage is reached. Zeners can maintain a constant value of voltage by changing its resistance

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13
Q

What is anode forward current of an SCR?

A

Maximum continuous current that can flow from cathode to anode

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14
Q

What are the two most common types of SCR’s?

A

Stud type and tab type

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15
Q

What is the most common way that SCRs are damaged?

A

Excessive gate power dissipation, or too much reverse gate voltage.

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16
Q

Formula for peak to RMS

A

Vp x .707

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17
Q

Formula for RMS to peak

A

Vrms/ .707

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18
Q

Single phase half wave Vrms to Vavg

A

Vrms x 0.45

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19
Q

Single phase full wave Vrms to Vavg

A

Vrms x 0.90

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20
Q

Three phase half wave Vrms to Vavg

A

Vrms x 1.17

use phase voltage

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21
Q

Three phase full wave Vrms to Vavg

A

Vrms x 1.35
use line voltage

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22
Q

Formula for Vinsta

A

Vpeak x SINtheta

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23
Q

Formula for firing angle

A

(Vinsta / Vpeak) SIN^-1

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24
Q

Formula for three phase half wave Vmin

A

Vpk x SIN30

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25
Q

Formula for three phase full wave Vmin

A

Vpk x SIN60

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26
Q

Formula for ripple volts

A

Vmax - Vmin

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27
Q

Formula for frequency of single phase half wave

A

1 x Hz

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28
Q

Formula for single phase full wave frequency

A

2 x Hz

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29
Q

Formula for three phase half wave frequency

A

3 x Hz

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30
Q

Formula for three phase full wave frequency

A

6 x Hz

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31
Q

When is the three phase half wave rectifier used?

A

In a Wye with a neutral system, when DC voltage output is low and current is high

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32
Q

What is commutation in a three phase rectification?

A

The switching from phase to phase

33
Q

When is a three phase full wave bridge rectifier used?

A

When large amounts of DC voltage output at a high efficiency is needed.

34
Q

Which three phase system can a full wave bridge rectifier be used on?

A

Any three phase system

35
Q

Which three phase system can a half wave rectifier be used on?

A

Wye with a neutral only

36
Q

Which system and rectifier usually needs no additional filtering?

A

Three phase full wave bridge rectifier

37
Q

What is the benefit of replacing the diodes in a three phase full wave bridge rectifier with SCRs?

A

SCRs provide phase control, allowing variable DC output

38
Q

In three phase rectifiers, the diodes must be rated for _____

A

Peak line to line voltage

39
Q

What minimum value of voltage does the rectified DC wave reach in a half wave rectifier?

A

50% of peak voltage

40
Q

What minimum value of voltage does the rectified DC wave reach in a full wave three phase rectifier?

A

86.6% of peak voltage

41
Q

What is the form factor used for three phase half wave rectification?

A

1.17

42
Q

What is the form factor for three phase full wave rectification?

A

1.35

43
Q

What is another name for the inverter?

A

Operational amplifier

44
Q

What is the controlled rectifier?

A

SCR

45
Q

What is triggering or firing of an SCR?

A

Turning it on

46
Q

What is commutating of an SCR?

A

Turning it off.

47
Q

If there was no load connected in series with the SCR, what would happen?

A

The SCR would short circuit.

48
Q

The maximum number of degrees that a firing angle can have is ____

A

180

49
Q

True or False: an SCR can replace a single phase bridge rectifier for phase control?

A

True

50
Q

What is an application for phase control with an SCR?

A

Varying the speed of a DC motor

51
Q

What is the primary use of the UJT?

A

Generate trigger pulses for SCRs and Triacs

52
Q

Is the UJT current or voltage sensitive?

A

Voltage sensitive

53
Q

What are the current and power ratings of UJTs?

A

Power is usually less than one third of a watt, currents are usually in the mA’s

54
Q

What is the firing voltage of the UJT?

A

A percentage of voltage across B2 and B1.

55
Q

When will the UJT switch on?

A

When voltage between emitter and B1 rises to two thirds of the voltage across B1 and B2

56
Q

What is the benefit of the UJT over the Diac?

A

Diac needs a specific firing voltage, the UJT can be varied and are lower than the Diac.

57
Q

What are some benefits of a full wave over half wave rectification?

A

Less ripple than half wave, higher average DC output

58
Q

What is the benefit of a six phase full wave rectifier?

A

Even less ripple than three phase

59
Q

How do you test an SCR and Triac with an ohmmeter?

A

Connect leads with the gate open, close the gate and there should be continuity, reopen the gate and there should still be continuity as the SCR is now triggered and will stay triggered.

Ohmmeter should read high resistance on both an open and closed gate

60
Q

When an SCR and Triac is turned off it will read ___ voltage and _____ current

A

Source voltage, 0 current.

61
Q

Which layer is the gate connected to in an SCR?

A

P

62
Q

Which layer is the gate connected to in a triac?

A

N

63
Q

In a triac, when the gate is the same polarity as M2 (anode) what wave will form?

A

Full AC wave

64
Q

In a triac, when voltage applied to the gate is the opposite of M2, what wave will form?

A

Half wave

65
Q

What is the PIV of a diode in a filtered rectifier?

A

Double the peak line

66
Q

What is the PIV of a diode in an unfiltered rectifier?

A

Peak of line

67
Q

Which thyristor can handle the highest power and frequency

A

SCR

68
Q

What is the variable resistor used for in a resistor capacitive triac circuit?

A

Used to control charge time of the capacitor

69
Q

What is the main purpose of a diac?

A

Phase shift a triac

70
Q

What is the truth table of an AND gate?

A

It’s 0001. Must have all inputs high to get an output (1 AND 1)

71
Q

What is the truth table of an Or gate?

A
  1. Whenever there is a 1 you get a high output.
72
Q

If a BJT has a base, what is the same component for the FET?

A

Gate

73
Q

If a BJT has a collector, what is the same component in a FET?

A

Drain

74
Q

If a BJT has an emitter, what is the same component of the FET

A

Source

75
Q

Which thyristor is current driven? Which is voltage driven?

A

Current: BJT

Voltage: JFET, MOSFET, IGBT

76
Q

Why are FETs voltage driven?

A

They have a very high input impedance, there is negligible current flow in the control circuit

77
Q

What are the two main characteristics of MOSFETS?

A

Very high input impedance, very fast switching speed.

78
Q

What are the benefits of the IGBT?

A

High input impedance, high switching speed, low saturation voltage, can handle large collector emitter current

Level 3 Electrical, BCIT (7 decks)

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