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1
Q

Triacs, Diacs, ujt’s, and scr’s operate only as

A

Switches

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2
Q

When transistors are used as switches, a ____ can be mounted across the transistor to prevent damage from high voltage spikes

A

Diode

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3
Q

The ___ region is the point at which the transistor is turned off and no current flows

A

Cutoff

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4
Q

A ____ serves as the control point for an SCR

A

Gate

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5
Q

A gate current is used to reduce the level of ____ voltage necessary for an SCR to conduct or fire

A

Breakover

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6
Q

_____ Control is the control of the time relationship between two events when dealing with voltage and current

A

Phase

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7
Q

____ Is one of the most suitable industrial applications of SCR’S

A

DC Motor control

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8
Q

A ____ is needed to properly test a SCR under operating conditions

A

Oscilloscope

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9
Q

Triacs are the equivalent of two SCR‘s connected in a ____ arrangement with gates, also connected to each other

A

Reverse-parallel

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10
Q

Triacs cannot replace SCR’s in ____ applications

A

High-current

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11
Q

And important feature of Triacs is the absence of a ____ condition of high voltages and high current, such as those found in diodes, and SCR’s

A

Reverse-breakdown

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12
Q

Electronically, a Diac operates in a manner similar to two ____ that are connected in series in opposite directions

A

Zener diodes

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13
Q

A diac has ____ resistance because it does not conduct current until the voltage crossed it reaches its break over voltage

A

Negative

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14
Q

Diacs are used almost exclusively as ___ devices

A

Triggering

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15
Q

The N-type material in a Uni Junction transistor functions as the ____ and has two leads

A

Base

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16
Q

As long as the emitter voltage remains less than the internal voltage, the emitter junction will remain ___ even at a very high voltage

A

Reverse biased

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17
Q

A UJT is typically used as a triggering circuit for a _____ or similar device

A

Triac

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18
Q

The “Pin” in pin photodiode stands for p-type material, ____, and n-type material

A

Insulator

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19
Q

In a two lead phototransistor, the ____ is replaced by a clear covering that allows light to fall on the base region

A

Base lead

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20
Q

In darkness, a phototriac is not triggered, the remaining leakage current is referred to as _____ current

A

Peak blocking

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21
Q

As electrons move across the _____ of a light emitting diode (LED) they give up extra kinetic energy, which is converted to light

A

Depletion region

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22
Q

In Optocoupler, uses a ____ glass sandwich to separate input from output

A

Dielectric

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23
Q

_____ current is the amount of current drawn by load when energized

A

Load

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24
Q

Photoelectric sensors that switch DC circuits normally use ____ as the switching element

A

Transistors

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25
Q

____ current flow is the movement of electrons from positive to negative

A

Conventional

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26
Q

Communication is the transmission of information from one point to another by means of _____ waves

A

Electromagnetic

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27
Q

A fiber optic receiver, normally contains a ____ that converts light back into electrical signal

A

Photodiode

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28
Q

The ____ is the first layer of protection for the glass or plastic core of an optical fiber cable

A

Cladding

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29
Q

_____ scan is a method of scanning in which the transmitter and receiver are housed in the same enclosure, and the transmitted light beam is reflected back to the receiver from a reflector

A

Retro reflective

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30
Q

____ scan distinguishes between shiny and non-shiny (matte) surfaces

A

Specular

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31
Q

In a ____ light source, the light source is turned on and off at a very high frequency, normally several (kHz)

A

Modulated

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32
Q

For optimum performance, the photoelectric sensor should be operated when its LED is _____

A

Green

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33
Q

A ____-operated photoelectric control is a photoelectric control that energizes the output switch with a target is present (breaking the beam)

A

Dark

34
Q

The best scanning method for height and distance monitoring is _____ scan with modulated controls

A

Direct

35
Q

The ____ light beam is the area of light that travels directly from the transmitter to the receiver

A

Effective

36
Q

An SSR circuit consist of an input circuit, a ____ circuit and an open circuit

A

Control

37
Q

The input circuit is deactivated when a voltage less then the specified minimum ____ voltage of the relay is applied

A

Dropout

38
Q

The ___ switching relay is the most widely used relay

A

Zero

39
Q

A____ switching relay has a built-in synchronizing circuit that controls the amount of output voltage as a function of the input voltage

A

Analog

40
Q

____ is the largest problem in applications that use an SSR

A

Temperature

41
Q

One of the significant advantages of an SSR over an EMR is it’s ____

A

Response time

42
Q

Even at full conduction, an SSR presents some residual resistance, which can create a voltage drop of up to approximately _____ in the load circuit

A

1.5v

43
Q

The ____ method is a method of SSR replacement in which a logical sequence is used to determine the reason for a failure

A

Circuit analysis

44
Q

_____ is a phenomenon that occurs when a relay fails to turn off because the current and voltage in the circuit reach zero at different times

A

Half-waving

45
Q

An RC circuit is a circuit in which resistance in capacitance, are used to help ____ the power in a circuit

A

Filter

46
Q

A solid state motor starter is in electronically operated switch (contactor) that uses solid-state components to eliminate mechanical contacts and includes ____

A

Overload protection

47
Q

___ trip is the trip point after the overloads have tripped and have been reset (motor, operating near or over nameplate rated current)

A

Hot

48
Q

A typical solid-state ____ circuit consist of both start, and run contactors connected in the circuit

A

Starting

49
Q

___ Start is the most common solid-state starting method

A

Soft

50
Q

___ stop is the most common solid-state motor starter Stopping method

A

Soft

51
Q

The instillation cost for ____ motor starters tend to be the highest

A

Solid state

52
Q

The ____ starting method provides the highest possible, starting to work per ampere of line current, and is the most effective means of motors, starting for applications, where the inrush current must be reduced with a minimum sacrifice of starting to torque

A

Auto transformer

53
Q

A thermistor is a ___-sensitive resistor

A

Temperature

54
Q

The operation of a thermistor is based on the ____-hole theory

A

Electron

55
Q

____ heated thermistors are used for precision, temperature measurement, and temperature compensation

A

Indirectly

56
Q

Cold resistance is measured at ____°c

A

25

57
Q

A photoconductive cell (photocell) is a device that conducts current when energized by _____

A

Light

58
Q

A photocell is in effect a variable

A

Resistor

59
Q

_____ and contamination are the primary causes of photocell failure

A

Humidity

60
Q

The primary difference between a photodiode and a regular diode, is that a photo diode has an addition of a _____ and it’s housing for focusing light on the PN junction

A

Lens

61
Q

Without light, the ____ of the photo diode is high

A

Resistance

62
Q

The ____ flowing through a photodiode, increases as the resistance decreases

A

Current

63
Q

A voltage output, pressure sensor typically outputs 0 VDC to ____ VDC proportional to the rating of the pressure sensor

A

10

64
Q

A current output pressure sensor typically outputs 4 mA to ____ mA proportional to the rating of the pressure sensor

A

20

65
Q

Pressure sensors are suited for a wide variety of pressure measurements on _____, pumps, and other similar equipment

A

Compressors

66
Q

A flow detection sensor is a sensor that detects the movement of a liquid or gas using a

A

Solid-state device

67
Q

A flow detection sensor operates on the principle of ____ conductivity

A

Thermal

68
Q

Because there is a small delay (usually less than 30 seconds) before a flow detection sensor, heats enough to signal no flow, the sensor acts like a ____ which allows for a short time delay to pass before signaling a problem

A

Motor overload protection

69
Q

A ____ sensor detect the proximity of a magnetic field

A

Hall effect

70
Q

Hall voltage varies, depending on how close the magnet is to the hall generator which acts as a ____ signal

A

Analog

71
Q

Typical hall effect sensor package configurations include cylinder, proximity vane, and ___

A

Plunger

72
Q

____ actuation is an active method of hall affect sensor activation, in which a magnet is oriented, perpendicular to the surface of the sensor and is usually centered over the point of maximum sensitivity

A

Head on

73
Q

Hall effect sensors are also used to replace mechanical ____ switches in applications that require the detection of an objects position

A

Limit

74
Q

A proximity sensor is a solid-state sensor that detects the presence of an object by means of a ____ sensing field

A

Electronic

75
Q

An ___ proximity sensor is a sensor that detects only conductive substances

A

Inductive

76
Q

Inductive proximity sensors operate on the ____ principle

A

Ecko

77
Q

____ sensors came to take material such as plastic glass water moist wood, etc.

A

Capacitive

78
Q

Generally any material with a _____ constant greater than 1.2 may be detected.

A

Dielectric

79
Q

The high frequency sound waves of an ultrasonic sensor, or typically in the ____ KHz range

A

200

80
Q

Material such as foam, fabric, and ____ are difficult for ultrasonic sensors to detect and are better detected by photoelectric or proximity sensors

A

Rubber

81
Q

___ mode is a method of ultrasonic sensor operation, in which the emitter and receiver are placed opposite of each other, so that the sound waves from the emitter are received directly by the receiver

A

Direct

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