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Unit 20 Chapters 84 - 89

Terms in this set (90)

A proportional only controller:
a. cannot maintain maximum value of the final element
b. signal output varies directly with set point error (or deviation)
c. can be compared to the cruise control on an automobile
d. will maintain measured variable at set point
e. will respond fully when deviation is high
b. signal output varies directly with set point error (or deviation)
Each pen in a multi-pen strip chart recorder is operated by a different:
a. sensor
b. transmitter
c. recorder
d. controller
e. process
b. transmitter
Control valves:
a. consist of a valve body accommodator
b. react to a controller input
c. provide a fixed resistance to flow
d. have one major component
e. require a pressure drop across the valve to maintain flow
e. require a pressure drop across the valve to maintain flow
A circular chart recorder:
a. provides a different function to a strip chart
b. is later design than a strip chart
c. may incorporate a bourdon tube
d. does not provide a permanent record
e. is used on a computer screen
c. may incorporate a bourdon tube
Circular charts are normally replaced every 24 hours but some charts may rotate for up to how many days?
a. 30
b. 2
c. 7
d. 14
e. 90
c. 7
A recorder utilizing a spiral bourdon tube will have a pen movement:
a. linear to the tube travel
b. proportional to the change in tube pressure
c. angular to the tube travel
d. range form 0 - 24 hours
e. range from 0 - 7 days
b. proportional to the change in tube pressure
Integral and Derivative functions are:
a. additions to all proportional controllers
b. also called right and reset controllers
c. an aid to improving effectiveness of the process controller
d. used in on/off control
e. integral to derivatives
c. an aid to improving effectiveness of the process controller
A control valve:
a. is always normally closed
b. is a form of variable resistance in a piping system
c. is nearly always reverse acting
d. must be part of a cascade control system
e. can, by itself, be part of a split range control loop
b. is a form of variable resistance in a piping system
A flapper-nozzle assembly is basic to all:
a. controllers
b. pneumatic transmitters
c. recorders
d. pneumatic devices
e. actuators
b. pneumatic transmitters
The pneumatic transmitter receives a constant air supply pressure of approximately:
a. 140 psi
b. 20 kPa
c. 140 kPa
d. 210 kPa
e. 30 kPa
c. 140 kPa
Automatic systems which can make decisions are termed:
a. annunciation systems
b. indicating systems
c. logic systems
d. open loop systems
e. go-to systems
c. logic systems
A common air pressure range for pneumatic control systems is:
a. 3 to 15 kPa
b. 20 to 100 psi
c. 20 to 30 kPa
d. 40 to 60 psi
e. 20 to 100 kPa
e. 20 to 100 kPa
A "control" should be considered as a special device which:
a. sends or transmits a positive rather than a negative signal
b. tries to maintain a set point
c. is logic device capable of making decisions
d. notifies operators of errors or faults in a system
e. leaves a hard-copy record of a system's performance
b. tries to maintain a set point
A sensing element sends its signal to the:
a. controller
b. recorder
c. control valve
d. transducer
e. transmitter
a. controller
Some of the components required to construct an automatic control loop are a sensing element, a transmitter, a _______, and a control valve.
a. controller
b. transformer
c. transducer
d. piping system
e. converter
a. controller
In an automatic control system the controller output changes the position of the:
a. recorder
b. transmitter
c. sensing element
d. final control element
e. indicator dial
d. final control element
In a "closed loop" system of control, the control will change:
a. automatically
b. both automatically and manually
c. manually
d. intermittently
e. inversely to the sign
a. automatically
The apparatus which converts current signals to pneumatic and pneumatic to current signals is called a:
a. converter
b. inducer
c. inverter
d. transducer
e. transformer
d. transducer
A sensing element receives its signal from the:
a. controller
b. recorder
c. control valve
d. transducer
e. controller variable
e. controller variable
Common indicators necessary for proper process operation may include:
a. interlocks and permissives
b. low water cutoffs, flame scanners and safety values
c. programmable logic controls
d. pressure, value position, and conductivity measurement devices
e. pneumatic, hydraulic, and electrical switches
d. pressure, value position, and conductivity measurement devices
A chromatograph used electronic devices which:
a. utilize electrical current as a measurement base
b. have inverse resistance properties relative to temperature
c. increase in resistance as temperature rises
d. work in conjunction with a thermocouple
e. are made of chromel and alumel
b. have inverse resistance properties relative to temperature
The advantage of using a venture tube, rather than an orifice plate for flow measurement is that it:
a. produces less permanent pressure loss
b. costs less to install
c. produces more pressure drop
d. is less bulky
e. is flexible
a. produces less permanent pressure loss
One of the most widely used process variables in a system is:
a. temperature
b. pressure
c. density
d. purity
e. flow
e. flow
A thermocouple measures:
a. pressure
b. temperature
c. flow
d. velocity
e. light
b. temperature
The coefficient of expansion of mercury is nearly linear for temperatures between:
a. -35 and 400 deg. C
b. -39 and 450 deg. C
c. -45 and 485 deg. C
d. -30 and 425 deg. C
e. 75 and 450 deg. C
b. -39 and 450 deg. C
In a glass stem thermometer the space above the liquid is usually:
a. nitrogen
b. argon
c. in a vacuum
d. at atmospheric pressure
e. approximately 50% air
c. in a vacuum
The constant head connection in a remote water level indicator is made to the:
a. feed water pump discharge
b. water space
c. atmosphere
d. feed water regulating valve
e. steam space
e. steam space
An inclined manometer is commonly used:
a. when very low pressures or vacuums are being measured
b. to measure high pressure differentials
c. in conjunction with a flexible rubber diaphragm
d. when reading accuracy is not critical
e. for measuring level
a. when very low pressures or vacuums are being measured
If the boiler pressure increases then, in the pressure gauge, the:
a. bourdon tube will tend to straighten
b. spring will compress more
c. bourdon tube will become less circular in cross-section
d. bourdon tube will become smaller in diameter
e. bourdon tube will tend to twist
a. bourdon tube will tend to straighten
A "U" tube manometer may be filled with:
a. a granular substance
b. nitrogen
c. heavy oils
d. a gaseous substance
e. light oils
e. light oils
Boiler modulating feedwater control flow rate depends on:
a. level set point
b. control valve position
c. actual level
d. feedwater pressure
e. set point, level, and valve position
e. set point, level, and valve position
On a steam boiler with single element feedwater control, the following item is measured:
a. steam flow
b. feedwater flow
c. boiler water level
d. fuel flow
e. feedwater pressure
c. boiler water level
Modulating combustion control will:
a. change air and fuel flow proportionally to steam pressure change
b. always be at set point when demand is 50%
c. alter only the air flow if a selector station is on manual
d. respond to changes in atmospheric pressure
e. always be a cascading control system
a. change air and fuel flow proportionally to steam pressure change
The drain of a hot water boiler low-water fuel cut-off should be opened to flush out any debris:
a. annually
b. daily
c. weekly
d. monthly
e. each shift
c. weekly
A mercury switch bulb is under high vacuum and contains inert gas:
a. so it will not explode
b. to prevent corrosion of contacts
c. to decrease electrical resistance
d. so contacts do not overheat
e. because the switch is normally closed
b. to prevent corrosion of contacts
The low water cut-off can be tested by:
a. raising steam pressure
b. shutting off the fire
c. shutting off the feedwater
d. opening the safety valve
e. closing the steam discharge valve
c. shutting off the feedwater
The float chamber of the low water cut-off is blown out often to prevent:
a. the chamber collecting sediment
b. the electric wiring from deteriorating
c. the mercury from oxidizing
d. the magnets rusting
e. water hammer in the chamber
a. the chamber collecting sediment
Modulating pressure control:
a. will shut down and start the burner
b. will control the fuel and air flow to the boiler
c. will control the temperature of the furnace
d. can be used on small boilers only
e. will control the pressure of the boiler
b. will control the fuel and air flow to the boiler
An advantage of the "electric probe" type low water cut-off is:
a. it can be incorporated on any size or type of boiler
b. it is simple in design with no moving parts
c. scale or sediment will not hinder its operation
d. all moving parts are easily accessible for cleaning and inspection
e. the probes will indicate a level even if not completely covered in water
b. it is simple in design with no moving parts
The low water fuel cut-off:
a. shuts off the water flow if the fuel pressure is low
b. shuts off the fuel if the water pressure is low
c. shuts off the fuel if the water level is low
d. controls the water level in the boiler
e. shuts off the fuel and water supply
c. shuts off the fuel if the water level is low
The operating pressure control will control the:
a. steam pressure in the boiler
b. gas pressure inn the boiler
c. water pressure in the boiler
d. boiler furnace pressure
e. stream pressure inn the stream header
a. steam pressure in the boiler
An intermittent pilot on an automatic boiler:
a. burns continuously, like the home furnace
b. lights before the main burner and goes out with it
c. is one which has been extinguished by a flame scanner
d. lights, completes a trial, and extinguishes after a main flame trial
e. must be manually ignited
b. lights before the main burner and goes out with it
Automatic boiler liquid fuel manual valves should be opened:
a. prior to pre-purge
b. after pre-purge and just prior to pilot ignition
c. immediately after completion of the pilot flame trial
d. after the automatic main burner fuel valve opens
e. with the automatic main burner fuel valve
a. prior to pre-purge
If a shutdown occurs during normal firing of a boiler and the steam pressure is below the normal cut-out value, the problem could be:
a. the sensing line to the combustion air proving switch has broken
b. main flame trial failure
c. pilot flame trial failure
d. igniter transformer failure
e. high steam pressure limit switch tripped
a. the sensing line to the combustion air proving switch has broken
At the end of the pre-purge the timer:
a. shuts down
b. opens the fuel valve
c. opens the pilot valve
d. goes through an ignition trial
e. energizes the ignition transformer
e. energizes the ignition transformer
On a gas fired automatic boiler a normal programmed start-up takes approximately:
a. 105 seconds
b. 55 seconds
c. 27 - 40 seconds
d. 120 seconds
e. 70 seconds
a. 105 seconds
During a programmed start-up if an igniter spark is visible but no flame appears the operator should suspect:
a. a boiler low water level
b. the main burner manual fuel valve is closed
c. the pilot manual fuel valve is closed
d. the scanner lead sulphide cell is weak
e. the boiler steam pressure operating control switch is open
c. the pilot manual fuel valve is closed
Before lighting off a boiler you should always purge the furnace in order to:
a. prove that the furnace and stack are clear
b. blow out any soot which may have collected in the tubes
c. cool the furnace so that premature combustion can occur
d. dry out the brickwork and check for leaks
e. remove any combustible gases which may have collected
e. remove any combustible gases which may have collected
The programmer will go through a post purge:
a. only if the pilot fails to ignite
b. only on flame failure
c. by manual involvement
d. on any type of shutdown except by power loss
e. on routine shut down only
d. on any type of shutdown except by power loss
On a boiler with high-low fire control, if the burner stays on "low-fire":
a. the modulating control may have failed
b. the igniter is defective
c. the safety lockout needs to be reset
d. the low air pressure switch has opened
e. the programmer is stuck in the pre-purge phase
a. the modulating control may have failed
Transmitters, which transmit digital codes directly to a computer, are known as:
a. digital transmitters
b. smart transmitters
c. analog transmitters
d. pneumatic transmitters
e. AND -OR devices
b. smart transmitters
Hard Drives are often backed up by copying their information to:
a. printers
b. removable media
c. plotters
d. registers
e. strip charts
b. removable media
A disk drive in a computer system is used to:
a. hide information
b. transfer information to the modem
c. print information
d. store information
e. transfer information to another floppy disk
d. store information
A device used to convert audio tones to computer language is commonly known as a:
a. transmitter
b. multiplexed
c. dot matrix
d. modulator/demodulator
e. CPU
d. modulator/demodulator
A digital input computer is protected from harmful voltages by means of:
a. splitter bars
b. fuses
c. isolating circuits
d. circuit breakers
e. stand-alone devices
c. isolating circuits
An anaolog control loop output must be put through a/an _____ before the computer can react tot he signal:
a. analog to digital converter
b. signal inverter
c. ROM detector
d. modem
e. CPU
a. analog to digital converter
Which of the following is not considered a high level language:
a. JAVA
b. Pascal
c. C++
d. Fortran
e. Assembler
e. Assembler
Desktop, laptop and handheld computers are examples of:
a. minicomputers
b. macro-computers
c. mainframes
d. micro-computers
e. multi-computers
d. micro-computers
Inputs for logic and supervisory computer functions are mainly:
a. by switch contacts
b. actions of an operator using the keyboard
c. stored on a disk which is required for operation
d. controlled by relays
e. non-decision making
a. by switch contacts
The applications of computers in power plants includes: mark all correct answers
a. storage of operating information for graphic display
b. safe start-up and shutdown of turbine and generators
c. control of fuel, air and feed water
d. supervision of plant operators
e. inventory control of parts and supplies
f. issuance of certificates of competency
a. storage of operating information for graphic display
b. safe start-up and shutdown of turbine and generators
c. control of fuel, air and feed water
e. inventory control of parts and supplies
Integral and derivative functions are:
a. additions to all proportional controllers
b. also called right and reset controllers
c. an aid to improving effectiveness of the process controller
d. used in on/off control
e. integral to derivatives
c. an aid to improving effectiveness of the process controller
An open loop control system requires:
a. a transducer and a recorder
b. minimum deviation from a set point
c. a very small amount of dead time or lag
d. constant attention
e. two final control elements
d. constant attention

open loop means manual operation
The basic login conditions that a computer uses to carry out actions are "AND", "OR", and "NOT".
fill in the blanks

1. the computer will trip the turbine if the lube oil temperature is to high "___" high vibration is detected
2. The automatic start sequence of a pump will not commence unless the discharge valve is open "___" there is water in the supply tank
1. OR

2. AND
A flapper nozzle assembly is basic to all:
a controllers
b. pneumatic transmitters
c. recorders
d. pneumatic devices
e. actuators
b. pneumatic transmitters
When a process variable has no method of sending information to the final control element the system is known as:
a. an automatic system
b. an open loop system
c. a cascading system
d. a feedback system
e. a feed forward system
b. an open loop system
An increase in steam pressure causes a sudden drop in water volume in the drum, and is known as:
a. swell
b. growth
c. rise
d. shrink
e. decline
d. shrink
Which of the following computer program languages is considered a "high level language":
a. English
b. WordPerfect
c. desktop publishing
d. Latin
e. Pascal
e. Pascal
The most reliable method of checking or testing a low fuel water cut off is to:
a. manually trip the cut off linkage to shut off the burner
b. blow the float chamber down to see if the burner will cut out
c. lower the water in the boiler to the level where the burner should cut out
d. blow the low water cutoff down through the water column until the burner cuts out
e. blow down the sight glass to see if the burner goes out
c. lower the water in the boiler to the level where the burner should cut out
Two element feedwater control:
a. measures water level and steam flow
b. compares forced draft to water level
c. compares fuel flow to steam flow
d. has one element in the feed control valve and one in the dearator
e. compares water level to the firing rate
a. measures water level and steam flow
Automatic systems which can make decisions are termed:
a. annunciation systems
b. indicating systems
c. logic systems
d. open loop systems
e. go to systems
c. logic systems
Sharing and transferring information between computers is termed:
a. analoging
b. multiplexing
c. plotting
d. number crunching
e. networking
e. networking
When a basic differential pressure transmitter is used for flow measurement:
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. movement of the force bar towards the nozzle will increase air flow
e. air supply pressure varies with the flow
c. output signal varies with the flow
If during startup the pilot fails to ignite a lockout switch will be energized:
a. after a trial period of 15 to 30 seconds
b. immediately
c. within 4-5 seconds
d. after the flame relay de-energizes
e. after the main burner flame ignites
a. after a trial period of 15 to 30 seconds
A helix strip bimetallic thermometer is wound spirally to:
a. dampen the motion
b. ease the installation
c. increase range of temperature measurement
d. amplify the motion
e. retard the expansion of the strip
d. amplify the motion
Computer information can be stored on a:
choose all correct
a. DVD
b. CD
c. hard drives
d. CPU
a. DVD
b. CD
c. hard drives
A strain gauge can be used to measure:
a. stresses in the pipe walls
b. pressure in the boilers
c. forces in the column
d. the densities of materials
e. the tension given by a compression load
c. forces in the column
Common indicators necessary for proper process operation may include:
a. interlocks and permissives
b. low water cutoffs, flame scanners and safety valves
c. programmable logic controls
d. pressure, valve position, and conductivity measurement devices
e. pneumatic, hydraulic, and electrical switches
d. pressure, valve position, and conductivity measurement devices
The common "modulating" control modes for a plant control system controller are:
a. integral and derivative
b. proportional and reset
c. proportional, reset, and integral
d. reset, integral, and rate
e. derivative, proportional, and integral
e. derivative, proportional, and integral
In an automatic control system the controller output changes the position of the:
a. recorder
b. transmitter
c. sensing element
d. final control element
e. indicator dial
d. final control element
A process variable which is adjusted in order to maintain or achieve some desired value of another variable is termed the:
a. process variable
b. final variable
c. manipulated variable
d. controlled variable
e. transmitting variable
c. manipulated variable
The major elements needed to construct automatic control loop instrumentation systems includes a sensing element, a _______, a controller and a control valve.
a. recorder
b. resistance
c. transmitter
d. manometer
e. float cage
c. transmitter
When a current signal is used for signal transmission it is a/an:
a. AC signal
b. ampere
c. power signal
d. generated signal
e. DC signal
e. DC signal
A bimetal thermometer reacts to changes of
a. pressure
b. flow
c. humidity
d. heat
e. temperature
e. temperature
Relative to flow, velocity is Kinetic energy and when velocity increase, the:
a. pressure and potential energy, will also increase
b. cross-sectional area of the piping will be increased
c. the mass quantity flowing per second will decrease
d. potential energy in the form of pressure will decrease
e. density will decrease
d. potential energy in the form of pressure will decrease
Calculate the height in meters between the water surface in an elevated tank and the ground to create a pressure of 335 kPa:
a. 13.13 m
b. 18.43 m
c. 34.15 m
d. 37.087 m
e. 39.939 m
c. 34.15 m

mH2O = kPa x 0.101972
When a diaphragm devise is used for boiler water level measurement, the boiler pressure is compensated for or off-set by:
a. using a bellows and the HP scale
b. a spring which balances the differential pressure
c. applying the pressure to both sides of the diaphragm
d. reversing the reference and variable legs
e. joining the reference and variable legs upstream of the device
c. applying the pressure to both sides of the diaphragm
When a basic differential pressure transmitter is used for flow measurement:
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. movement of the force bar towards the nozzle will increased air bleed
e. air supply pressure varies witht he flow
c. output signal varies with the flow
A control valve that has one plug that moves upward to close the port is called:
a. reverse acting single ported
b. double seated direct acting
c. reverse acting diaphragm
d. direct acting single ported
e. electrically operated
a. reverse acting single ported
A proportional controller:
choose all correct
a. may have a pneumatic or electronic analog output
b. provides a proportional output based on the error between process variable and set point
c. requires no operator input
d. provides on/off control
e. is typically something the operator cannot touch
a. may have a pneumatic or electronic analog output
b. provides a proportional output based on the error between process variable and set point
In a basic pneumatic transmitter, movement of the flapper towards the nozzle will:
a. increase the nozzle bleed
b. change the size of the supple orifice
c. maintain steady transmitter supply pressure
d. change transmitter supply pressure
e. increase feedback bellows pressure
e. increase feedback bellows pressure
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