ac test questions

Question 1

I am the sensing device that detects the condition of the process variable Who am I?

Answer 1

Primary Element

Question 2

A bonded wire strain gauge is used in what type of comparator circuit allowing a small change in resistance to cause a voltage variation

Answer 2

A Bridge comparator

Question 3

I operate by sending sound waves toward the target and measuring the time it takes for the pulses to bounce back Who am I?

Answer 3

Ultrasonic Sensor

Question 4

How is an inductive proximity sensor actuated ?

Answer 4

by a metal object

Question 5

The _______ is a non-contact temperature detector that can measure the infrared radiation emitted from an object. Thus making it possible to measure temperatures from a remote location. the infrared radiation is often focused onto a thermopile or an LDR

Answer 5

Pyrometer

Question 6

A stainless steel sheath thermocouple when heated produces what

Answer 6

a small dc voltage

Question 7

What does signal conditioning involve

Answer 7

Converting input and output signals to a usable form

Question 8

There is a strain gauge mounted on the outside of a tube. the force applied to this sensor causes it to bend and change its

Answer 8

resistance

Question 9

A strain gauge under tension has its resistance affected according to the following relationship R = kL / cma

therefore the strain gauge resistance will

Answer 9

increase due to decreased cross sectional area and increased length

Question 10

A shaft encoder is coupled to the output shaft of an electric motor. The output of the shaft encoder is connected to a positioner controller. Which specification detail for the encoder will determine the resolution of the positioning system.

Answer 10

Pulses per revolution

Question 11

A new steady-state condition occurs ______ time constant(s) after a controlled variable is exposed to an energy change.

Answer 11

5

Question 12

I am sent to the final control element Who am i

Answer 12

Control signal

Question 13

Compared to an open loop system closed loop control systems

Answer 13

Require feedback concerning the status of the process

Question 14

generally what is the essential difference between an open loop and a closed loop control system

Answer 14

Closed loop systems incorporate feedback

Question 15

two ingredients are added together, processed and then stored within an industrial bakery.

this is an example of

Answer 15

batch process

Question 16

What type of maintenance technicians are becoming more popular in the industry due to their flexibility and cost effectiveness

Answer 16

multi skilled technicians

Question 17

which elements and signals of a control system do not exist in an open loop configuration

• comparator
• error signal
• summing amplifier
• feedback signal
• all of the above

Answer 17

all of the above

Question 18

of the devices listed below

• motor
• heater
• fan

which could classify as an actuator

Answer 18

all of them

Question 19

which of the following devices could be classified as a sensor

• thermistor
• clutch
• relay
• LED indicator

Answer 19

thermistor

Question 20

I am an electrical meter consisting of several thermocouples connected in series to provide a higher voltage output who am i

Answer 20

Thermopile

Question 21

This meter uses a strip consisting of two metal alloys with different coefficients of thermal expansion that are fused together and formed into a single strip complete with an indicating mechanism calibrated for temperature reading who am i

Answer 21

Bimetallic

Question 22

A thermistor requires which type of signal conditioning

Answer 22

Cold junction compensation

Question 23

Solids transfer thermal energy by which process

Answer 23

Conductance

Question 24

When testing an RTD or a thermistor why is it necessary to disconnect it from the circuit

Answer 24

the transducer must be isolated from the other circuit components that would affect the measurement

Question 25

What does the V stand for in this formula | Q= VA

Answer 25

velocity

Question 26

which of these are classified as fluids

-solids
-gasses
-liquids
-vapors

Answer 26

gasses liquids and vapors