3A2 Chapter 11

Question 1

The control loop is made up of four basic functional blocks

1) process
2) process variable
3) measurement
4) automatic controller
5) the final control element

A) 1,3,4,5
B) 3,4
C) 1,2,3
D) 1,2,3,4,5

Answer 1

A) 1,3,4,5

Question 2

For purposes of control theory, a process can be defined as an action in which material and/or _______ is modified to a different form

A) fluids
B) energy
C) gas
D) oil

Answer 2

B) energy

Question 3

Flow rate is often measured with a _______

A) pedometer
B) ultrasonic meter
C) orifice plate
D) velocity meter

Answer 3

C) orifice plate

Question 4

Process parameters such as temperature, pressure, and flow require continuous measurements in real time. If review of the measurements is desired, provision must be made to capture the parameters with respect to time

A) true
B) false

Answer 4

A) true

Question 5

List the four types of final actuators

1) conveyor belt
2) flapper valve
3) globe valve
4) a Louvre
5) motor’s variable speed drive
6) a compressor’s inlet guide vanes

A) 1,2,3,4,5,6
B) 1,6
C) 4,5,6
D) 1,4,5,6

Answer 5

D) 1,4,5,6

Question 6

Pneumatic systems can operate on:

1) compressed air
2) hydraulic fluid
3) nitrogen
4) water
5) methane

A) 1,2,3,4,5
B) 1,3,5
C) 1,5
D) 1,2,5

Answer 6

B) 1,3,5

Question 7

Transmitters convert a process physical quantity such as level, pressure, flow, or temperature into a representative pneumatic analog signal, usually ______

A) 0-25 kPa
B) 20-100 kPa
C) 4-20 mA
D) 1-100%

Answer 7

B) 20-100 kPa

Question 8

Control valves are responsible for providing process changes by manipulating fluid flow in a pipeline. They are called a primary control element (PCE), as they are the final devices that the controller uses to affect corrective action to the process

A) true
B) false

Answer 8

B) false

Question 9

Pneumatic level switches are available for:

1) level
2) pressure
3) viscosity
4) temperature
5) density
6) flow

A) 1
B) 1,2,3
C) 1,4,5,6
D) 1,2,4,6

Answer 9

D) 1,2,4,6

Question 10

List the three main elements of an analog instrumentation loop

1) process set point
2) transmitter
3) controller
4) instrument air
5) final control element

A) 1,2,3,4,5
B) 2,3,5
C) 1,3,4
D) 1,2,3,4,5

Answer 10

B) 2,3,5

Question 11

_______ are used to convert physical quantities of flow, level, temperature, pressure, and weight into electrical signals that represent those quantities as accurately as possible

A) controllers
B) control valves
C) transmitters
D) level switches

Answer 11

C) transmitters

Question 12

Square root extractors are used to convert squared signals from _____ flowmeters to _______ flow signals

A) digital, analog
B) differential, linear
C) normal, normal
D) steam, Boiler feedwater

Answer 12

B) differential, linear

Question 13

The controller uses an operational amplifier to perform a mathematical summation, in order to compare the input signal (process variable) with a set point that is established by operations personnel. If the process is not at the set point value, the mathematical functions present in the controller will produce an output signal that will correct the process

A) true
B) false

Answer 13

A) true

Question 14

A typical controller station allows the operator to:

1) view and change the set point
2) view feed forward settings
3) view e process variable
4) switch from auto to manual
5) view process history

A) 1,2,3,4
B) 1,2,3,4,5
C) 1,3,5
D) 1,2

Answer 14

C) 1,3,5

Question 15

The main devices used as final control elements are:

1) control valves
2) variable speed motor drives
3) steam flow
4) speed governors
5) level switches
6) damper positioners

A) 1,6
B) 4,5,6
C) 1,2,6
D) 1,2,4,6

Answer 15

D) 1,2,4,6

Question 16

The term “digital” describes computer systems that use the binary number system of ______ and _____

A) zeros, tens
B) ones, zeros
C) tens, one hundreds
D) disc, hard drives

Answer 16

B) ones, zeros

Question 17

Large control rooms almost invariably contain a nu,bear of video ______ consoles attached to a large distributed control system data highway

A) game
B) display
C) operator
D) digital

Answer 17

C) operator

Question 18

Smart transmitters transmit process information in either a digital or the 4-20 mA analog for,at. They can be rezeroed and rearranged remotely, using a hand held calibrator

A) true
B) false

Answer 18

A) true

Question 19

The smart transmitter is really a digital device, containing an on board ______ complete with memory

A) microprocessor
B) calibrator
C) video
D) process variable

Answer 19

A) microprocessor

Question 20

The majority of final control elements are, and will continue to be _______

A) control valves
B) microprocessors
C) hand held computers
D) globe valves

Answer 20

A) control valves

Question 21

In on-off control, the controller signal to the final control element is either ______ positive or _______ negative

A) 0%, 100%
B) 0%, 50%
C) 100%, 100%
D) 100%, 24%

Answer 21

C) 100%, 100%

Question 22

Most common three examples of on-off control are:

1) temperature controlled exhaust fan in a compressor building
2) Boiler feedwater to a Boiler
3) a thermostat controlled forced air furnace
4) Boiler fuel gas flow
5) the compressed air supply to a storage tank

A) 1,2,5
B) 1,3,5
C) 3,4,5
D) 4,5,6

Answer 22

B) 1,3,5

Question 23

The difference between the set point and the actual value of the process variable is known as offset. Offset is an inherent characteristic of all reset only controllers

A) true
B) false

Answer 23

B) false

Question 24

The percent of the process variable range that causes _____ change in controller output is often called the proportional band

A) 25%
B) 100%
C) 20%
D) 75%

Answer 24

B) 100%

Question 25

Integral control, often called reset, responds to both the ______ and ______ duration of the deviation

A) offset, span
B) speed, magnitude
C) amount, time
D) error, reset

Answer 25

C) amount, time

Question 26

Reset on integral time can be varied by manipulating the integral adjustment valve

A) true
B) false

Answer 26

A) true

Question 27

The difference between feedback and feedforward control is apparent. Feedback control works to eliminate errors, whereas feedforward control operates to prevent errors from occurring in the first place

A) true
B) false

Answer 27

A) true

Question 28

In a closed loop control configuration, a measurement is made of the controlled variable, and this is compared with the desired ______ or _______

A) output, signal
B) value, set point
C) PV, SP
D) product, material

Answer 28

B) value, set point

Question 29

The difference between feedback and feedforward in a controller is; feedback control works to eliminate errors, where feedforward control operates to prevent errors from occurs in the first place

A) true
B) false

Answer 29

A) true

Question 30

Cascade control is achieved by the use of two controllers, but only one \_\_\_\_\_\_
A) SP
B) PV
C) OP
D) final control element

Answer 30

D) final control element

Question 31

Ratio control is often associated with process operations when it is necessary to continuously mix two or more variables to produce a ________ output that is used as a controlled variable

A) double
B) single
C) triple
D) strong

Answer 31

B) single

Question 32

Loop alarms are devices that signal the existence of an abnormal condition by means of an audible or visible discrete change, or both, intended to attract attention

A) true
B) false

Answer 32

A) true

Question 33

Emergency shutdown (ESD) devices are operated by ________

A) air and hydraulics
B) hydraulics, electricity and air
C) air, hydraulics, electricity, or combinations of all three

Answer 33

C) air, hydraulics, electricity, or combinations of all three

Question 34

An emergency shutdown could be activated ________ or_______

A) locally, remotely
B) fast, slow
C) automatically, manually
D) full, partial

Answer 34

C) automatically, manually

Question 35

What are the most common conditions monitored by a sensor and that activate shutdowns:

1) high or low temperature
2) loss of lubricating oil
3) vibration
4) low flow
5) high or low level
6) high or low pressure
7) combustible or toxic gas

A) 1,3,4,5,6
B) 1,4,5,6,7
C) 1,2,3,5,6
D) all of the above

Answer 35

D) all of the above