[D2L Practice] 104A

Question 1

What are the sub-components all types of controllers in a closed-loop control system?

1) sensor
2) a comparator or null detector
3) a transmitter
4) all of the above

Answer 1

All of the above

Question 2

What type of temperature controller is used in a typical residential household?

Answer 2

Thermostat

Question 3

What are the main type of sensors used in the HVAC/R industry?

1) temperature
2) pressure
3) humidity
4) all of the above

Answer 3

All of the above

Question 4

What type of sensor consists or two different strips of dissimilar metal?

Answer 4

bimetal strip

Question 5

In a bimetal strip the two metals have the same coefficients of linear thermal expansion

T or F

Answer 5

False, different coefficients of thermal expansion

Question 6

The bending of a bimetal strip is based on pressure

T or F

Answer 6

False

Question 7

What type of sensor can be formed in a Helix, disk or spiral shape?

Answer 7

bimetal strip

Question 8

Where would you find an averaging element?

Answer 8

Across the face of a heating coil

Question 9

What does a bellows react to?

1) pressure
2) temperature
3) resistance
4) A & B

Answer 9

pressure

Question 10

where is the best place to mount a fast response element with regards to off cycle defrost?

Answer 10

evaporator

Question 11

What sensor uses a thin flexible membrane that stretches across the mouth of a bell shaped container?

Answer 11

flexible diaphragm

Question 12

What sensors react to pressure?

1) diaphragm
2) bellows
3) bourdon tube
4) all of the above

Answer 12

All of the above

Question 13

Where is a flexible diaphragm most commonly used with regards to heating?

Answer 13

combustion air proving switch

Question 14

Why would use a bellows over a diaphragm?

Answer 14

more accurate

Question 15

Where is a bourdon tube most commonly used?

Answer 15

Refrigeration gauge

Question 16

A bourdon tube will straighten out as pressure increases

T or F

Answer 16

True

Question 17

Which sensor is the most accurate?

1) bourdon tube
2) bimetal strip
3) diaphragm
4) electronic

Answer 17

electronic

Question 18

What do humidity sensors measure?

Answer 18

wet bulb temperature

Question 19

What types of humidity sensors are used?

1) hygroscopic sensor
2) electronic sensor
3) all of the above

Answer 19

All of the above

Question 20

A hygroscopic sensor will absorb moisture when the humidity decreases

T or F

Answer 20

False, absorbs moisture when the humidity increases

Question 21

Which is an example of a hygroscopic sensor?

1) bimetal strip
2) nylon ribbon
3) copper wire

Answer 21

nylon ribbon

Question 22

What is a comparator?

Answer 22

compares two electronic signals in order to detect the difference between a reference signal and a feedback signal

Question 23

What is a transmitter?

Answer 23

transmit signal to the actuator in the controlled device

Question 24

What is the difference between the actual condition and the desired condition at any moment in time?

1) controller deviation
2) controller set-point
3) controller offset
4) controller span

Answer 24

controller deviation

Question 25

The Output signal changes in the same direction that the controlled variable changes. An increase in the controlled variable results in an increased output signal.

Answer 25

Direct Acting

Question 26

What is the maximum and minimum valves to which you can set a controller?

Answer 26

controller range

Question 27

What is another word for design condition?

Answer 27

controller set-point

Question 28

What is the single parameter that represents the difference between the highest and lowest values the user can set the controller?

Answer 28

controller span

Question 29

What are the signals for an on/off control mode?

Answer 29

digital

Question 30

What is another name for a variable resistor?

Answer 30

analog