Deck 21: Three-Phase Systems in Power Applications

Question 1

The typical output for a normally operating thermocouple is in the range of 1 V to 10 V.

Answer 1

False

Question 2

Displacement transducers can be made using a variety of types of optical or electrical circuits.

Answer 2

True

Question 3

One method of providing an accurate thermocouple interface is:

A)capacitive coupling.
B)to use a reference thermocouple.
C)to use a reference voltage in the feedback circuit.
D)to use a swamping resistor.

Answer 3

to use a reference thermocouple.

Question 4

What affects the accurate operation of a resistance bridge measuring temperature?

A)input voltage
B)length of wires going to the detector
C)ambient temperature
D)all of the above

Question 5

Circuits that contain features such as common-mode rejection, isolation, gain, etc. are called:

A)signal conditioners.
B)interfaces.
C)thermocouples.
D)none of the above.

Question 6

The ac value that is equal to the same dc heating effect is usually called:

A)peak value.
B)heat value.
C)rms value.
D)average value.

Question 7

Strain gauges are used to detect minute changes in temperature.

Question 8

Which of the following is not a temperature sensor?

A)thermocouple
B)thermistor
C)resistance temperature detector
D)triac

Question 9

A triac must be triggered for each alternation for proper operation.

Question 10

The aperture time for a sample-and-hold circuit refers to the change in the voltage from the
sampled value during the hold interval time.

Question 11

What device has the same function as a thermocouple but has a more linear output?

A)resistance temperature detectors
B)analog temperature device
C)capacitive temperature detector
D)linear temperature device

Question 12

RTDs and thermistors both operate on the same principle of resistive change with temperature.

Question 13

A cold-junction:

A)opposes measured temperature.
B)can have an unpredictable effect on the thermocouple effect.
C)has a value that depends on ambient temperature.
D)all of the above.

Question 14

Pressure sensors make use of an RTD for their operation.

Question 15

What device is formed by adjoining two dissimilar metals?

A)pop-sensor
B)thermocouple
C)sequencer
D)none of the above

Question 16

An input transducer converts:

A)voltage to current.
B)a nonelectrical quantity to an electrical quantity.
C)current to voltage.
D)an electrical quantity to a nonelectrical quantity.

Question 17

Basic analog physical parameters such as angular position, temperature, pressure, strain, and flow rate can be measured by what devices?

A)Transmissions
B)Transducers
C)Telemeters
D)Transmitters

Question 18

Conversion of analog signals to digital signals is common in most controlled industrial processes.

Question 19

A SCR is used mainly in the control of AC circuits.

Question 20

Analog-to-Digital conversion takes a specific analog quantity and produces a unique binary
number to represent that quantity.

Question 21

The deformation of a material due to force acting on it is called:

A)stress.
B)compression.
C)pressure.
D)strain.

Question 22

The quantity usually measured using a spring-supported seismic mass is:

A)velocity.
B)weight.
C)volume.
D)acceleration.

Question 23

The device often used as an electronic switch in many applications is the:

A)SCR.
B)SPDT.
C)diode.
D)SPST.

Question 24

Which of the following is not a force-related parameter?

A)motion
B)strain
C)pressure
D)velocity

Question 25

Sample and hold circuits:

A)increase resolution.
B)convert analog voltages to a binary number.
C)reduce quantization error.
D)all of the above.

Question 26

Which of the following components is not used as a temperature measurement device?

A)thermocouple
B)RTD
C)triac
D)All are used to measure temperature changes.

Question 27

Since the triac can be triggered to allow current to flow both directions, it can be used in:

A)phase control.
B)dc circuits.
C)ac circuits.
D)any of the above.

Question 28

Precise control of a triac to prevent high-frequency transients is called:

A)microcontroller pulsing.
B)zero-voltage switching.
C)pulse switch triggering.
D)negative feedback biasing.

Question 29

A device that exhibits a change in resistance based on a change in pressure is called a:

A)gauge transducer.
B)psi gauge.
C)pressure transducer.
D)none of the above.

Question 30

One common method of measuring flow rate of a fluid through a pipe is the:

A)differential pressure method.
B)dynaflow method.
C)wein-bridge method.
D)hall effect.

Question 31

Which of the following ADC circuits has the highest resolution?

A)16 bit
B)one that has the highest aperture time
C)4 bit
D)none of the above

Question 32

What quantity indicates change in positions of a body or point?

A)motion coefficient
B)displacement
C)FIFO
D)relative velocity

Question 33

Displacement transducers make use of which of the following?

A)capacitance
B)magnetism
C)light
D)any of the above

Question 34

Voltage storage in a sample and hold amplifier is accomplished by:

A)a JFET switch
B)a holding inductor.
C)a holding capacitor.
D)the output buffer op-amp.

Question 35

Which of the following devices changes resistance inversely with the temperature?

A)thermocouple
B)thermistor
C)RTD
D)triac