Book 9 Flashcards
The forms commonly used for power-plant equipment control include analog, digital, mechanical, pneumatic and:
Select one:
a.
Electrical
b.
Manual
c.
Thermal
d.
Magnetic
Electrical
Thermometers, pressure gauges, and level indicators in the field are known as what?
a.
Errors
b.
Recorders
c.
Indicators
d.
Transmitters
Indicators
A basic electric control circuit has 2 major pieces
Select one:
a.
sensor switch and final control element
b.
sensor and thermostat
c.
controller and sensor
d.
solenoid valve and final control element
sensor switch and final control element
A device which will cause a visible light signal to become an instrument analog signal is the:
Select one:
a.
Photoelectric transducer
b.
Controller
c.
PE switch
d.
Current-to-pneumatic transducer
Photoelectric transducer
Only certified “Safety PLCs” can be used for
Select one:
a.
Air dryer sequencing
b.
Conveyor sequencing
c.
Lime mud mixing systems
d.
Burner management systems
Burner management systems
Which is NOT an example of wireless transmission protocol?
a.
Wireless HART
b.
Wi-Fi
c.
Fibre optic
d.
Bluetooth
Fibre optic
A two-position controller compares conditions to a set point and:
Select one:
a.
Starts or stops a process
b.
Modulates the final control element
c.
Automatically readjusts the set point
d.
Maintains the final control element position at 50%
Starts or stops a process
A valve which gives good throttling action, takes less actuator force, but does not seal well is a:
Select one:
a.
Double seated valve
b.
Reverse acting valve
c.
Single seated valve
d.
Direct acting valve
Double seated valve
Fail-closed solenoid operated valves open when
Select one:
a.
a coil is electrically energized
b.
pressure below the valve disc overcomes the spring pressure above the disc
c.
an electric motor opens the valve
d.
it is de-energized
a coil is electrically energized
A control loop controller:
Select one:
a.
Sends a signal to a primary element
b.
Measures the manipulated variable value, eliminating the need of a primary element
c.
Eliminates all setpoint deviation
d.
Constantly compares a process variable to the set point
Constantly compares a process variable to the set point
A sensing element sends its signal to
Select one:
a.
a transmitter
b.
an air line
c.
a conveyer
d.
a recorder
a transmitter
Cascade control utilizes:
Select one:
a.
One controller, two transmitters and two valves
b.
Two controllers, one transmitter and two valves.
c.
Two controllers, two transmitters and two valves.
d.
Two controllers, two transmitters and one valve.
Two controllers, two transmitters and one valve.
Depending on the process application, control valves are selected to do all of the following except one:
a.
Fail closed
b.
Fail in the last position (fail first)
c.
Fail open
d.
Fail in the last position (fail last)
Fail in the last position (fail first)
A PLC needs to be able to check itself for safe operation. This occurs during the:
Select one:
a.
maintenance scan
b.
program scan
c.
input scan
d.
housekeeping scan
housekeeping scan
Which chart recorder came first?
a.
Circular strip
b.
Strip
c.
Circular
d.
Strip chart circular
Circular
An open loop control system requires:
Select one:
a.
A transducer and a recorder
b.
More accurate sensing devices
c.
A very small amount of dead time or lag
d.
Constant operator attention
Constant operator attention
Where are programs stored if they are always required and must not be modified?
a.
Random access memory (RAM)
b.
Erasable program read-only memory (EPROM)
c.
Hard disk drive (HDD)
d.
Read-only memory (ROM)
Read-only memory (ROM)
Transmitters with built-in microprocessors are known as:
Select one:
a.
Digital transmitters
b.
Smart transmitters
c.
Analog transmitters
d.
Modems
Smart transmitters
Level, pressure, flow, and temperature are examples of:
Select one:
a.
Transmitters
b.
Measured variables
c.
Sensing elements
d.
Manipulated variables
Measured variables
Electro-hydraulic valves open slowly when energized. However, when electric power is interrupted, a powerful _____________ quickly slams the valve shut, thereby stopping the fuel flow to the burner.
a.
Motor
b.
Spring
c.
Bellows
d.
Diaphragm
Spring
A thermocouple measures:
Select one:
a.
Pressure
b.
Temperature
c.
Velocity
d.
Light
Temperature
What is a computer program?
a.
A collection of wires and silicon chips
b.
A series of signals from transmitters
c.
A series of instructions to do a task
d.
A series of tasks for the operator
A series of instructions to do a task
A controller is a device that primarily:
Select one:
a.
Sends or transmits a positive rather than negative signal
b.
Tries to maintain a set point
c.
Records a system’s performance
d.
Is a logic device capable of making decisions
Tries to maintain a set point
The capability of modular PLCs can be expanded by adding___________.
Select one:
a.
memory
b.
hard drives
c.
input and output cards
d.
transmitters and receivers
input and output cards
A circular chart recorder:
Select one:
a.
Provides a different function than a strip chart.
b.
Is newer design than a strip chart.
c.
Incorporates a bourdon tube.
d.
Does not provide a permanent record.
Incorporates a bourdon tube.
One of the most important and commonly measured process variables in a system is:
Select one:
a.
Viscosity
b.
Pressure
c.
Density
d.
Composition
Pressure
The inclined “U” tube manometer:
Select one:
a.
Will measure pressure in kPa
b.
Can only be used with mercury
c.
Is more accurate than the “U” tube manometer
d.
Is more difficult to read than the U-tube manometer
Feedback
Is more accurate than the “U” tube manometer
When a basic differential pressure transmitter is used for flow measurement:
Select one:
a.
The low-pressure side is upstream of the orifice plate.
b.
The transmitter sends a signal directly to the final control element.
c.
Output signal varies with the flow.
d.
Air supply pressure varies with the flow.
Output signal varies with the flow.
Integral and Derivative functions
Select one:
a.
may be combined with multi-position controllers
b.
are also called feed-forward and cascade functions
c.
help to maintain a process variable on set-point.
d.
are used in on-off control.
help to maintain a process variable on set-point.
When a float is used for measuring level, and installation within a vessel is impractical, the float is installed in a
Select one:
a.
Float manometer
b.
Float cage
c.
Differential head meter
d.
Diaphragm level indicator
Float cage
What types of service are nutating discs not suitable for?
a.
Low pressure or high temperature
b.
High pressure or low temperature
c.
High pressure or high temperature
d.
Low pressure or low temperature
Feedback
High pressure or high temperature
Approved Burner Management Systems used on smaller packaged boilers:
Select one:
a.
are fully-configurable by field operators, using an HMI
b.
have a limited selection of field-configurable parameters, such as purge, trial for ignition and flame failure response time
c.
have fully configurable sequences and operating parameters
d.
can only be set up by burner technicians using laptop computers and ladder logic
have a limited selection of field-configurable parameters, such as purge, trial for ignition and flame failure response time
Which devices are used by an electronic control system?
a.
Sensors and transmitters
b.
Rectifiers and inverters
c.
Monitors and modems
d.
Resistors and transistors
Sensors and transmitters
An analog control loop output must be put through a _____ before the computer can react to the signal.
Select one:
a.
Digital converter
b.
Signal inverter
c.
ROM detector
d.
Multiplexer
Digital converter
Computer software used for managing maintenance cannot:
Select one:
a.
prepare scheduled maintenance work orders
b.
manually verify equipment and parts inventory
c.
track equipment operating times
d.
generate maintenance cost reports
manually verify equipment and parts inventory
In a pneumatic control system, the nozzle receives a regulated air supply pressure of approximately:
Select one:
a.
140 Pa
b.
20 kPa
c.
140 kPa
d.
200 kPa
140 kPa
In an automatic control system the controller output signal goes to the:
Select one:
a.
Transmitter
b.
Sensing element
c.
Final control element
d.
Process variable
Final control element
In an automatic control system, the controller output signal changes the position of the:
Select one:
a.
Recorder
b.
Transmitter
c.
Sensing element
d.
Final control element
Final control element
Pressure controllers can be divided into two classes:
Select one:
a.
High and low temperature
b.
High and low pressure
c.
High and low flow
d.
High and low voltage
High and low pressure
Which type of controller can respond before the change takes place?
a.
Proportional
b.
Integral
c.
Feedback
d.
Feedforward
Feedforward
The electrical output from a thermocouple is measured by a:
Select one:
a.
Milliamp meter
b.
Watt meter
c.
Milliwatt meter
d.
Millivolt meter
Millivolt meter
When are modulating motors used?
a.
To position valves and dampers
b.
As electromechanical actuators
c.
For two-position control of steam or hot water to radiators
d.
To operate two-position valves
To position valves and dampers
What is one advantage of a modular PLC?
a.
Input and output cards can be added or removed
b.
Input or output cards cannot be swapped for other kinds of cards
c.
Self-contained similar to monolithic PLC
d.
Defective cards cannot be replaced
Input and output cards can be added or removed
A valve actuator:
Select one:
a.
Cannot be reverse acting
b.
Will always have one side of the diaphragm open to atmosphere
c.
Is a two-position device
d.
Position is a function of controller output
Position is a function of controller output
A computer displays information to the operator via
Select one:
a.
a monitor
b.
an icon
c.
a CAD
d.
a CPU
a monitor
Why were PLCs first developed?
Select one:
a.
To remove the need for feedback loops
b.
To eliminate the need for control programming language
c.
To allow processes to be easily and quickly re-configured
d.
To allow the use of analog input and output signals
To allow processes to be easily and quickly re-configured
A thermocouple consists of:
Select one:
a.
Two dissimilar wires connected together to form a measuring and a reference junction
b.
Two dissimilar wires connected to a battery
c.
A thermally-conductive fluid, held within a fine tube
d.
A thermistor, coupled to a wheatstone bridge
Two dissimilar wires connected together to form a measuring and a reference junction
Digital output signals are processed by _____ before an analog controls can react to them.
Select one:
a.
Digital receivers
b.
Logic controllers
c.
the CPU
d.
Analog converters
Analog converters
Orifice plates, venturi tubes and nozzles belong to the group called:
Select one:
a.
Flow meters
b.
Pressure meters
c.
Head meters
d.
Analog meters
Head meters
A proportional controller:
Select one:
a.
Is also called a multi-position controller
b.
Provides a proportional output based on the error between process variable and set-point
c.
Provides on-off control
d.
Allows the process variable to always be maintained at the set-point
Provides a proportional output based on the error between process variable and set-point
What are the essential components of a modular PLC?
a.
Panel lights and warning lights
b.
Three discrete inputs and two analog output cards
c.
Transmitters and CPU
d.
Power supply and CPU
Power supply and CPU
The variable area meter consists of:
Select one:
a.
A fluid being measured, flowing through the tube from the top to the bottom
b.
A float across which the differential pressure varies
c.
A tapered tube in which the fluid being measured flows through the tube from the bottom to the top
d.
An opening that can be varied as required
A tapered tube in which the fluid being measured flows through the tube from the bottom to the top
Automatic systems that can make decisions are termed:
Select one:
a.
Annunciation systems
b.
Indicating systems
c.
Logic systems
d.
Open loop systems
Logic systems
A Bourdon tube may be manufactured in the shape of a helix so that _______________________ than a standard bourdon tube:
Select one:
a.
Its final output has less travel
b.
They can fit in narrower enclosures
c.
Higher pressures can be sensed
d.
It has enough power and rotation to move the pens of a recorder without the use of gears
It has enough power and rotation to move the pens of a recorder without the use of gears
In a basic electrical control system the device that senses a drop in air temperature is called the:
Select one:
a.
Final controlled device
b.
Pneumatic temperature sensor
c.
Humidistat
d.
Thermostat
Thermostat
A control device which will change one form of energy into another form of energy is the:
Select one:
a.
Logic device
b.
Primary element
c.
Transducer
d.
Transmitter
Transducer
A PLC with an HMI can signal an alarm by: (choose all that are correct)
Select one or more:
a.
Sounding a siren or horn
b.
Flashing an equipment icon on the HMI screen
c.
Operating a beacon
d.
Turning the HMI screen a different colour
Sounding a siren or horn, Operating a beacon, Flashing an equipment icon on the HMI screen, Turning the HMI screen a different colour
The apparatus which converts current signals to pneumatic and pneumatic to current signals is called a:
Select one:
a.
Converter
b.
Inverter
c.
Transducer
d.
Transformer
Feedback
Transducer
Which of the following is an advantage of electrical control systems?
Select one:
a.
Electricity is readily available
b.
The necessary computer programming is easy to learn
c.
Controller/actuators require a dedicated air supply lowering the power requirements
d.
Signals from sensing elements produce one discrete digital output
Electricity is readily available, Controller/actuators require a dedicated air supply lowering the power requirements
What is the approximate arc of a bourdon tube pressure gauge?
a.
270°
b.
280°
c.
260°
d.
290°
270
Which two types of ultrasonic flow meters are commonly in use?
a.
Transit-time and Doppler
b.
Weir and Coriolis
c.
Transit-time and Doppler effect
d.
Magnetic and variable area
Transit-time and Doppler
Name the control loop in which no check is made to determine whether the corrective action has accomplished the desired objective.
a.
Feedback
b.
Closed
c.
Open
d.
Partial
Open
A flowing liquid has kinetic energy as a function of its velocity. When its velocity increases
Select one:
a.
Potential energy in the form of pressure will also increase
b.
The cross-sectional area of the piping must increase
c.
The mass quantity flowing per second will decrease
d.
Potential energy in the form of pressure will decrease
Potential energy in the form of pressure will decrease
A helix strip bimetallic thermometer is wound spirally to:
Select one:
a.
Dampen the motion of the pointer
b.
Ease its installation
c.
Increase the range of temperature it can measure
d.
Amplify the motion of the pointer
Amplify the motion of the pointer
Pneumatic signals operate between:
Select one:
a.
20 and 200 kPa
b.
0 and 100 kPa
c.
50 and 500 kPa
d.
20 and 100 kPa
20 and 100 kPa
A sensing element responds to the value of the
Select one:
a.
Controller
b.
Recorder
c.
Control valve
d.
Measured variable
Measured variable
The Bourdon tube is often shaped in the form of a “C”, having an arc span of about:
Select one:
a.
180 degrees
b.
200 degrees
c.
90 degrees
d.
270 degrees
Feedback
270 degrees
A _______ is NOT a discrete input.
Select one:
a.
limit switch
b.
temperature sensor
c.
push button
d.
proximity switch
temperature sensor
If the combustion air pressure is too low to deliver the correct amount of combustion air, what will the low-pressure controller do?
a.
Close an electric circuit and close the fuel valves
b.
Open an electric circuit and open the fuel valves
c.
Open an electric circuit and close the fuel valves
d.
Close an electric circuit and open the fuel valves
Open an electric circuit and close the fuel valves
PLCs are commonly used for:
Select one:
a.
packaged boiler burner management systems
b.
operating equipment in the correct sequence
c.
simultaneous manual control of several control devices
d.
running maintenance software.
operating equipment in the correct sequence
What are the basic logic conditions?
a.
TRUE, FALSE, NEITHER
b.
UP, DOWN, MIDDLE
c.
YES, AND, NO
d.
Not, And, OR
Not, And, OR
A variable which is adjusted in order to maintain or achieve some desired value of another variable is termed the:
Select one:
a.
Process variable
b.
Final variable
c.
Manipulated variable
d.
Controlled variable
Manipulated variable
The type of circuit used to store (write) and retrieve (read) information from a computer is known as its:
Select one:
a.
Bytes
b.
Motherboard
c.
RAM
d.
ROM
RAM
An unpredicted change in a plant process is called a/an:
Select one:
a.
Disruption
b.
Disturbance
c.
Error
d.
Malfunction
Disturbance
An orifice plate with a round opening that is centred in the middle of the plate is called a:
Select one:
a.
Concentric orifice
b.
Eccentric orifice
c.
Concentric flange
d.
Centralized flow
Concentric orifice
When a process variable has no method of sending information to the final control element (a valve for example) the system is known as:
Select one:
a.
An open loop system
b.
A cascade system
c.
A feedback system
d.
A feedforward system
An open loop system
Which of the following is NOT a functionality provided by a human machine interface to the operator?
a.
Start and stop process
b.
Acknowledge and reset alarms
c.
Observe normal and adverse operating conditions
d.
Reconfigure input and output devices
Feedback
Reconfigure input and output devices
What are two methods of signal transmission?
a.
Digital and fibre optic
b.
Digital and current
c.
Analog and transducer
d.
Analog and digital
Analog and digital
A proportional-only controller:
Select one:
a.
Are mostly used for on/off control.
b.
Compare actual conditions to controller outputs.
c.
Must provide reset action.
d.
Cannot always maintain the process variable exactly at the set-point.
Cannot always maintain the process variable exactly at the set-point.
Putting a controller on manual control means:
Select one:
a.
The operator controls the final control element.
b.
The controller output responds to a process variable.
c.
There is no control of the final control element.
d.
The operator manually adjusts the process by changing the process variable signal
The operator controls the final control element.
Which of the following is an advantage of electrical control systems?
a.
Controller/actuators require a dedicated air supply, lowering the power requirements
b.
Signals from sensing elements produce one discrete digital output
c.
Single controller/actuator combinations are possible without the need of a source of compressed air
d.
The necessary computer programming is easy to learn
Single controller/actuator combinations are possible without the need of a source of compressed air
A basic, filled system thermometer consists of a temperature-sensitive bulb, a capillary tube, and a pressure-sensing device. Which pressure-sensing device would suit this purpose?
a.
Diaphragm
b.
Rheostat
c.
Thermistor
d.
Thermometer
Diaphragm
When controller output is proportional to the amount of deviation, the controller is:
Select one:
a.
Integral
b.
Two-position
c.
Proportion plus reset plus rate
d.
Proportional
Proportional
Liquids must be vapourized
Select one:
a.
In order to measure density
b.
If purity is to be measured
c.
When a chromatograph is being used
d.
When conductivity is measured
When a chromatograph is being used
Control valves
Select one:
a.
Must fail closed
b.
Provide variable resistance in a piping system
c.
Provide tight flow shut-off
d.
Must modulate from fully open to fully shut
Provide variable resistance in a piping system
A DC motor used to provide precise repeatable positioning of valves or dampers is the
Select one:
a.
stepper motor
b.
solenoid
c.
modulating motor
d.
Wheatstone bridge
stepper motor
The bimetal sensing element consists of a strip made up of two thin layers of metal with:
Select one:
a.
Similar rates of thermal expansion
b.
Different rates of thermal expansion
c.
Different specific heats
d.
Different resistances
Feedback
Different rates of thermal expansion
The main component of any computer is the:
Select one:
a.
Keyboard
b.
Screen
c.
Memory
d.
Central processing unit
The correct answer is: Central processing unit
The filled system thermometer of a remote bulb thermostat maybe filled with a vaporizing liquid that reacts in what way?
a.
Varies in level with temperature
b.
Varies in pressure with temperature
c.
Changes color with temperature
d.
Changes volume with temperature
Varies in pressure with temperature
A “U” tube manometer may be filled with:
Select one:
a.
A granular substance
b.
Nitrogen
c.
Ethyl alcohol
d.
Light oils
Light oils
A control valve that has one plug that moves upward to close the port is called:
Select one:
a.
Reverse acting
b.
Double seated direct acting.
c.
Reverse acting diaphragm actuated.
d.
Direct acting
Reverse acting
Which part of a transmitter contains the valve capsule, restrictor, spring, and exhaust valve?
a.
Flapper-and-nozzle
b.
Pneumatic relay
c.
Pressure reducer
d.
Feedback bellows
Pneumatic relay
A valve body that seals on the down stroke is:
Select one:
a.
Reverse acting
b.
Single sealed
c.
Direct acting
d.
Double sealed
Direct acting
An electrical actuator used to position dampers and control valves is called:
Select one:
a.
A controller
b.
A relay
c.
A transformer
d.
A modulating motor
A modulating motor
Which of the following is NOT a component of a modular PLC?
a.
Digital input/output card
b.
Central processing unit
c.
Discrete input card
d.
Analog input card
Digital input/output card
On-off thermostats are equipped with:
Select one:
a.
An open contact switch
b.
Humidity compensation
c.
Two or more switches, operated in sequence
d.
A potentiometer
An open contact switch
What is an example of a final control element?
a.
A thermostat that controls air temperatures in ducts
b.
A damper motor that operates air louvres
c.
A rheostat that varies current in a circuit
d.
A relay that starts/stops a pump
A damper motor that operates air louvres
A PLC needs ___________ to accept operator input:
Select one:
a.
an HMI
b.
an analogue input card
c.
specialized software
d.
an internet or network connection
an HMI
A recorder utilizing a spiral Bourdon tube will have a pen movement:
Select one:
a.
On a logarithmic scale
b.
Proportional to the change in tube pressure
c.
Range of 0 to 24 hours
d.
Range of 0 to 7 days
Proportional to the change in tube pressure
Data cannot be permanently stored on a
Select one:
a.
CD-ROM
b.
Hard disk
c.
CPU
d.
Monitor
Monitor
