Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Electronics > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

An SCR differs From an ordinary diode in that it passes significant current.

A

FALSE

It does not pass significant current, even when forward biased, UNLESS The anode voltage equals or exceeds the forward break over voltage. And when forward breakover voltage is reached, the SCR switch is on and becomes highly conductive.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Low current SCRs Can operate with an anode current of less than 1A.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The size of an SCR decreases with an increase in current reading.

A

FALSE

It increases in size.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When an SCR is forward biased, it operates similar to a regular semiconductor diode.

A

FALSE

Reverse Bias

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When an SCR is forward biased, there’s a small amount of forward leakage current called forward blocking current.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When an applied voltage is above the forward breakover voltage (V sub BRS), the SCR fires or turns on.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Increasing values of a forward bias can be used to reduce the amount of forward breakover
voltage if necessary to get an SCR to conduct.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

And SCR normally can be triggered into conduction by applying a pulse of control current to the gate.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The correct method of turning off an SCR is to apply a proper signal to the gate of the SCR.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Static turn on does not damage the SCR, provided the surge current is limited.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The internal structure of an SCR consists of a PNP later.

A

FALSE

The internal structure consists of 2 PN junctions join together that form a PNPN layer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The equivalent circuit analogy is used to understand a complex device.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Equivalent circuit of an SCR is a circuit consisting of three interconnected PNP transistors.

A

FALSE

Is a circuit consisting of interconnected PNP and NPN transistors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The most basic application of an SCR is a AC switch.

A

FALSE

DC Switch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

3 SCRs are required for AC switching.

A

FALSE

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Regular diodes cannot be used for AC and DC switching.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

An SCR can be turned on at different points in the conducting cycle.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The proper operation of an SCR requires the correct mounting and cooling of the device.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Press-fit SCRs are installed using the same procedure used for mounting and stud mounted diodes.

A

FALSE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The major advantages of using flat-pack and press-pack SCRs is the decreased surface area.

A

FALSE

The advantage of flat-pack and press-pack SCRa is the increased surface area available for thermal conduction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

A good technician can troubleshoot a light-sensing circuit by using signal substitution or circuit disturbances.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

An SCR can be triggered by shorting the anode to the gate.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Information provided by manufactures on the installation of SCRs does not need to be followed.

A

FALSE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

SCRs cannot be used in circuits to provide heat control.

A

FALSE

They can be used in heat control circuits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

An integrated circuit has an electronic component (SCR) and an electromechanical component (relay) in the same circuit.

A

FALSE

A Hybrid circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

By using diodes, switches, and an SCR firing circuit, visual an audible alarms can be activated to serve as warning Signals.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Unlike across the line starters, solid-state starters reduce inrush current.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Solid state starters provide smooth, stepless acceleration in applications such as starting conveyors, compressors, and pumps.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

A typical solid-state starting circuit consists of starter and run contactors.

A

TRUE

30
Q

And SCR cannot be used for overvoltage protection.

A

FALSE

And SCR can be used for overvoltage protection as a power supply protection circuit.

31
Q

A _____________ Is a four layer PNPN semi conductor device.

A

SCR

32
Q

An SCR uses a _____________ as an electrode.

A

Anode, cathode, gate

33
Q

Silicone controlled rectifiers are used in power switching and _____________ circuits.

A

Phase control, battery charger, and inverter circuits.

34
Q

Large SCR assemblies with many individual devices connected in series are used in _____________ converter stations.

A

High-voltage voltage DC

35
Q

An uncontrolled method of turning on an SCR is a _____________ turn-on.

A

Voltage breakover, static, and thermal.

36
Q

_____________ turn-on is the only correct way to turn on SCR.

A

Gate

37
Q

_____________ turn on as a method of turning on an SCR when the voltage across the SCR terminals exceeds the maximum voltage rating of the device.

A

Voltage breakover

38
Q

_____________ turn on is a method of turning on an SCR when a fast rising voltage is applied across the terminals of a triac.

A

Static

39
Q

When a gate is pulsed or triggered in the proper forward-bias applied to the SCR, the _____________ regions close and the current begins to flow through the SCR.

A

Depletion

40
Q

With _____________ control, the speed of a motor, the brightness of the lamp, and the output of an electric-resistance heating unit can be controlled.

A

Phase

41
Q

A _____________ circuit is an SCR that has the ability to turn on at different points of the conducting cycle of a half-wave rectifier.

A

Half-wave phase control

42
Q

When minimizing SCRs exposure to heat, a high temperature device, such as a _____________, should be shielded from radiating heat directly on the SCR case.

A

Lamp, power transformer, resistor.

43
Q

The advantage of flat-pack and _____________ SCRs is the increased surface area available for thermal conduction.

A

Press-pack

44
Q

The operations manual of the test instrument use when troubleshooting an SCR should be consulted for all measuring _____________.

A

Precautions, limitations, and procedures.

45
Q

In addition to being used in light dimmers and speed controls, SCRs can be used in industry to control the power in _____________.

A

Battery chargers, power supplies, and machine tools.

46
Q

Using a _____________ circuit, the control temperature can be maintained within 1°F over temperature range of 20°F to 150°F.

A

Bridge

47
Q

An SCR can be used in circuits to provide _____________ for motor control, photo enlargers, and other times or delayed functions.

A

Time delay

48
Q

The operation of a hybrid circuit begins with a switch in the _____________ position.

A

RESET

49
Q

_____________ is a form of reduced voltage starting for standard motors.

A

Solid state starting

50
Q

The heart of the solid-state starter is the _____________, which controls motor voltage, current, and torque during acceleration.

A

SCR

51
Q

An _____________ characteristic curve shows the operating characteristics of an SCR when It’s gate is not connected.

A

Voltage-current

52
Q

In the _____________ region, the resistance of the SCR is very small.

A

Forward avalanche

53
Q

_____________ turn-on is a method of turning on an SCR with a proper signal is applied to the gate at the correct time.

A

Gate

54
Q

The _____________ defines the level of voltage over a given time. That causes the device to turn on.

A

DV/DT Rating

55
Q

A _____________ circuit is typically added across the SCR terminals to protect the SCR when static turn-on is a problem.

A

Snubber

56
Q

_____________ turn-on is a method of turning on an SCR when heat levels exceed the limit of the SCR, typically 230°F.

A

Thermal

57
Q

_____________ bias exists when the positive lead of the voltage source is attached to the cathode and the negative lead is attached to the anode.

A

Reverse

58
Q

The _____________ and collector of each transistor represent the gate connection.

A

Base

59
Q

_____________ is the control of the time relationship between two events when dealing with voltage and current.

A

Phase control

60
Q

A _____________, like a heat sink, is an integral part of the heat transfer path of an SCR.

A

Mounting surface

61
Q

The press-fit package is designed primarily for _____________ insertion into a slightly undersized hole in the heat exchanger (heat sink).

A

Forced

62
Q

To mount a _____________ SCR, a whole may be punched in reamed in a flat plate, extruded and sized in sheet metal, or drilled and reamed.

A

Press-fit

63
Q

Typically, _____________ SCRs fastened to heat sinks to ensure good heat flow.

A

Stud mounted

64
Q

A _____________-pack SCR must be properly installed to provide Max with the heat transfer.

A

Press

65
Q

The output of an SCR must be tested under operating conditions using a _____________.

A

Test circuit and and oscilloscope

66
Q

Low power and some high power SCRs tested using an analog _____________.

A

Ohmeter

67
Q

A _____________ circuit is a circuit that mixes mechanical devices and electronic devices in the same circuit.

A

Hybrid

68
Q

A _____________ circuit is used to control the pulses to the gate.

A

Electronic triggering

69
Q

________________ also provide smooth acceleration and minimize starting to work.

A

Solid state starters

70
Q

A power supply protection circuit is often referred to as a ________________ circuit.

A

Crowbar

Electronics (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions