3A2 Chapter 11 Flashcards
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
A) 1,3,4,5
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
B) energy
Flow rate is often measured with a _______
A) pedometer
B) ultrasonic meter
C) orifice plate
D) velocity meter
C) orifice plate
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
A) true
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
D) 1,4,5,6
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
B) 1,3,5
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%
B) 20-100 kPa
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
B) false
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
D) 1,2,4,6
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
B) 2,3,5
_______ 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
C) transmitters
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
B) differential, linear
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
A) true
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
C) 1,3,5
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
D) 1,2,4,6
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
B) ones, zeros
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
C) operator
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
A) true
The smart transmitter is really a digital device, containing an on board ______ complete with memory
A) microprocessor
B) calibrator
C) video
D) process variable
A) microprocessor
The majority of final control elements are, and will continue to be _______
A) control valves
B) microprocessors
C) hand held computers
D) globe valves
A) control valves
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%
C) 100%, 100%
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
B) 1,3,5
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
B) false
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%
B) 100%
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
C) amount, time
Reset on integral time can be varied by manipulating the integral adjustment valve
A) true
B) false
A) true
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
A) true
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
B) value, set point
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
A) true
Cascade control is achieved by the use of two controllers, but only one \_\_\_\_\_\_ A) SP B) PV C) OP D) final control element
D) final control element
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
B) single
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
A) true
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
C) air, hydraulics, electricity, or combinations of all three
An emergency shutdown could be activated ________ or_______
A) locally, remotely
B) fast, slow
C) automatically, manually
D) full, partial
C) automatically, manually
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
D) all of the above
