B1-4 Controls And Instrumentation Flashcards
A variable which is adjusted by the controller output signal to bring the process variable back to the desired value or set point is called the: A) controlled variable B) process variable C) manipulated variable D) final variable E) transmitting variable
C) manipulated variable
The device which converts a current signal to a pneumatic signat or a pneumatic signal to a current signal is called a/an A) inverter B) transformer C) transducer D) transmitter E) inducer
C) transducer
One pound per square inch (psi) pressure is equal to: A) 1 Newton per meter squared B) 1 kilopascal C) 6.89 kPa D) 1 kilogram pre meter squared E) 100 kPa
C) 6.89 kPa
A final control element normally receives its signal from the: A) control valve B) transmitter C) process variable D) recorder E) controller
E) controller
In an automatic control system, the controller output signal manipulates the: A) sensing element B) transmitter C) control valve D) recorder E) primary element
C) control valve
Temperatures are measured by: A) bourdon tubes B) thermocouples C) pressure differential D) thermo wells E) watt meters
B) thermocouples
A Mercury filled thermometer can be used in the range: A) -100*C to 1000*C B) -273*c to 1000*C C) 0*C to 460*C D) -39*C to 460*C E) -460*C to 212*C
D) -39C to 450C
To measure the quantity of steam flow in a pipe line by means of a head meter, the primary element senses:
A) change in temperature
B) change in density
C) moisture content, or “dryness fraction”
D) steam drum pressure
E) differential pressure
E) differential pressure
The main physical difference between a flow nozzle and a Venturi tube is that:
A) the flow nozzle incorporates an orifice plate
B) a Venturi tube does not contain a diverging section
C) a Venturi tube converging section controls discharge flow
D) a flow nozzle does not contain a converging section
E) a flow nozzle does not contain a diverging section
E) a flow nozzle does not contain a diverging section
When differential pressure manometers are used, the external leg is often called the \_\_\_\_\_\_\_ or constant head. A) variable B) reference C) water D) average E) liquid
B) reference
Most solenoid valves are unlike globe valves in that:
A) they cannot be used in piping transporting gases or vapours
B) the fluid flows upward through the valve seat
C) they can be used to regulate the flow of the fluid
D) they do not close tightly and some leakage occurs
E) the fluid flows downward through the valve seat
E) the fluid flows downward through the valve seat
The output pressure signal of a pneumatic transmitter is usually:
A) the same as the primary element output signal
B) inversely proportional to nozzle pressure
C) directly proportional to nozzle pressure
D) fed to a final element of a control loop
E) a function of supply pressure
C) directly proportional to nozzle pressure
In an automatic control system, the controller output manipulates the: A) sensing element B) thermocouple C) recorder D) transmitter E) control valve
E) control valve
A proportional only controller:
A) has derivative action only
B) has an output that varies with the difference between actual and set point conditions
C) will respond more quickly when deviation is high
D) can only maintain a maximum value of a final element output
E) will always maintain the measured variable at set point
B) has an output that varies with the difference between actual and set point conditions
When a recorder receives a pneumatic signal from a transmitter, the recorder incorporates a:
A) reverse signal transponder
B) flapper nozzle assembly
C) spiral bourdon tube, capsule or bellows
D) transducer
E) pneumatic relay
C) spiral bourdon tube, capsule or bellows
The component that is an integral part of an infrared flame safeguard system is the: A) lead sulphide cell B) operating controller C) low pressure controller D) pressure regulator E) ammeter
A) lead sulphide cell
With single element feedwater control, the level transmitter output is: A) constant regardless of level B) sent to a selector station C) proportional to drum level D) received by a final element E) a function of steam flow
C) proportional to drum level
Single element feedwater control systems are suitable for maintaining the boiler water level when:
A) the boiler has a small water capacity to steam flow ratio
B) the boiler is of a fire tube design
C) the fluctuations in load are fast and large
D) the boiler is of a water tube design
E) the fluctuations in load are slow and small
E) the fluctuations in load are slow and small
A Mercury tube switch is typically a part of a: A) thermohydraulic regulator B) modulating combustion controller C) thermo expansion regulator D) two element feedwater controller E) low water fuel cutoff
E) low water fuel cutoff
Match the type of a maintenance of a low water fuel cutoff for a steam boiler with its required frequency.
A) dismantling the device
B) draining of a float chamber while the burner is in
C) routine checks for leaks and abnormal conditions
D) tripping the boiler by shutting off water supply
1) daily. 2) weekly operation. 3) monthly. 4) annually
1) daily - C) routine checks for leaks and abnormal conditions
2) weekly operation - D) tripping the boiler by shutting off water supply
4) monthly - B) draining a float chamber while the burner is in
5) annually -A) dismantling the device
On some low water cutoff devices, a three wire Mercury switch is used instead of a two wire switch in order to:
A) open a steam pressure relief valve
B) start an auxiliary cooling fan
C) cut the main power to the boiler controls
D) send a signal to the plant master
E) energize an audible alarm
E) energize an audible alarm
The drain on a hot water boiler low water fuel cutoff should be opened to flush out any buildup of sediment: A) weekly B) daily C) annually D) monthly E) each shift
A) weekly
A float operated level control:
A) will recognize swell and shrinkage and correct the feedwater flow
B) is only used on small boilers
C) is used on water tube boilers only
D) must be used when a boiler is manually operated
E) is installed inside a boiler steam drum
B) is only used on small boilers
When an electric probe type low water fuel cutoff is employed on a heating boiler, it is important to:
A) ensure the probe housing is properly insulated to prevent electrocution
B) vent off any hydrogen caused by electrolysis of the water
C) add salt to the boiler water to ensure good conductivity
D) check and clean the probes at regular intervals
E) ensure the boiler is frequently blown down
D) check and clean the probes at regular intervals
A low water fuel cutoff is fitted to a boiler to prevent:
A) damage to the boiler from an overheated condition
B) the fire from shutting off too quickly and damaging the boiler
C) damage to the radial stays in the steam dome
D) shutting off the water when there is no fuel
E) damage to the boiler from over pressure
A) damage to the boiler from an overheated condition
On automatic boilers, liquid fuel manual valves should be opened:
A) prior to prepurging
B) with the automatic main burner fuel valve
C) after prepurge and just prior to pilot ignition
D) after the automatic main burner valve opens
E) immediately after completion of the pilot flame trial
A) prior to prepurging
When an automatic unattended boiler starts up, the program timer will first:
A) start the forced draft fan
B) energize the ignition transformer and pilot gas solenoid valve
C) energize the main gas valve
D) start the post purge period
E) energize the main feedwater valve
A) start the forced draft fan
The function of a programming control is to:
A) regulate the fuel supply to the burner
B) regulate the combustion controls during startup
C) regulate fuel, air, and water supply to the boiler
D) supervise feedwater supply to the boiler
E) control the boiler blowdown rate
B) regulate combustion controls during startup
During a programmed startup, if an igniter spark is visible but no flame appears, the operator should suspect:
A) a boiler steam pressure operating control switch is open
B) the pilot manual fuel valve is closed
C) the scanner lead sulphide cell is weak
D) the main burner manual fuel valve is closed
E) a boiler low water level
B) the pilot manual fuel valve is closed
An interrupted pilot of an automatic boiler:
A) lights, completes a trial, and extinguishes after a main flame is ignited
B) must be manually ignited
C) is one which has been extinguished by a flame scanner
D) burns continuously, like that in a home furnace
E) lights before the main burner and goes out with it
A) lights, completes a trial, and extinguishes after a main flame is ignited
In computer terminology, "RAM" means: A) rear access module B) random access memory C) read access memory D) random acting memory E) read alone memory
B) random access memory
The common standard control modes for a plant control system are:
A) proportional and reset
B) integral and derivative
C) reset, derivative, and rate
D) proportional, integral, and derivative
E) proportional, reset, and integral
D) proportional, integral, and derivative
To take the place of circular strip chart recorders in older instrumentation systems, a computerized plant can store information in: A) ROM and a floppy disk B) ROM and a modem C) RAM and a hard disk D) RAM and a plotter E) RAM and a multiplexer
C) RAM and a hard disk
A multiplexer is used to regulate tasks in sequence as often as: A) once per hour B) four times or more per second C) once every few seconds D) four times per minute E) twice per minute
B) four times or more per second
A digital input computer is protected from harmful voltages by means of: A) circuit breakers B) stand alone devices C) fuses D) splitter bars E) isolating circuits
E) isolating circuits
When a process variable has no method of sending information to the final control element, the system is called: A) an automatic system B) a cascading system C) a feedback system D) an open loop system E) a feedforward system
D) an open loop system
Four common signals used to operate control devices include mechanical, pneumatic, electrical, and: A) liquid B) solid C) hydraulic D) digital E) fiber optics
C) hydraulic
Automatic systems which can make decisions are termed: A) annunciation systems B) logic systems C) indicating systems D) open loop systems E) cascading systems
B) logic systems
The device which converts a current signal to a pneumatic signal or a pneumatic sigma to a current signal is called a/an: A) transducer B) inducer C) inverter D) transmitter E) transformer
A) transducer
A control device which changes one form of energy into another form of energy is the: A) controller B) transducer C) primary element D) transmitter E) transponder
B) transducer
With regards to the use of a head meter type transmitter, the quantity of steam flow through a pipe line is related to:
A) a change in temperature
B) the moisture content, or “dryness fraction”
C) the velocity of the fluid
D) fluid density
E) steam drum pressure
C) the velocity of the fluid
In glass stem thermometer, the space above the Mercury is sometimes filled with nitrogen so that:
A) the vaporizing temperature of the Mercury is lowered
B) they can be used in a horizontal position
C) they can be used at a very low temperature
D) they can be used at higher temperature
E) the Mercury does not etch the glass
D) they can be used at higher temperature
When heat is applied to a thermocouple: A) the helix moves B) the tube expands C) a voltage is generated D) the difference in temperature is measured E) the free end moves
C) a voltage is generated
The device that is most suitable for indicating the highest temperature is the: A) resistance thermal device B) Mercury in glass thermometer C) alcohol in glass thermometer D) bimetal thermometer E) thermocouple
E) thermocouple
In a glass stem thermometer, the space above the liquid is usually: A) a halogenated hydrocarbon B) alcohol in gas form C) a vacuum D) pressurized E) a mixture of ammonia and water
C) a vacuum
When a plant control panel is equipped with a CRT display, the operator:
A) will not be able to determine the transmitter signal
B) can not intervene to make set point changes
C) will not have printout capabilities
D) can view only one signal line trend display
E) can display several different process conditions at the same time
E) can display several different process conditions at the same time
In an automatic control system, the controller output manipulates the: A) transmitter B) sensing element C) recorder D) control valve E) thermocouple
D) control valve
A valve which has two seats, gives good throttling action, but does not close tightly is the: A) double seated valve B) reverse acting valve C) reverse seated valve D) single seated valve E) direct acting valve
A) double seated valve
A control valve that closes on the upstroke is: A) reverse acting B) single seated C) direct acting D) double seated E) uni directional
A) reverse acting
In most solenoid valve, the upstream line pressure will:
A) act to open the valve
B) be less than downstream pressure
C) be sensed by a transmitter
D) act to close the valve when the solenoid is deenergized
E) first pass through a restriction or nozzle
D) act to close the valve when the solenoid is deenergized
The second element of a two element feedwater control system compensates for, or offsets:
A) level variation due to pneumatic time lag
B) differential feedwater pressure
C) changes in steam pressure
D) feedwater temperature variation
E) shrinkage and swell
E) shrinkage and swell
A combustion air proving switch: A) senses oxygen content of the air B) senses ID fan speed C) detects oxygen in the flue gas D) senses wind box pressure E) senses FD fan speed
D) senses wind box pressure
A packaged steam boiler modulating combustion control system will:
A) maintain drum level within a desired range
B) maintain flue gas temperature at a desired set point
C) alter fuel flow without changing the air flow
D) alter air flow without changing the fuel flow
E) maintain boiler steam pressure at a desired value
E) maintain boiler steam pressure at a desired value
The CSA-B51 (Canadian standards association, boiler, pressure vessel, and pressure piping code) states that a steam boiler not under continuous attendance by a certified operator shall be equipped with a low water fuel cutoff device which: A) must be a normally open switch B) can also operate a feedwater pump C) may be equipped with isolation valves D) must have an automatic reset device E) serves no other purpose
E) serves no other purpose
The connecting lines of a hot water boiler low water fuel cutoff should be opened to clean out any debris: A) annually B) monthly C) weekly D) daily E) each shift
A) annually
The low water fuel cutoff on a steam boiler should be completely overhauled: A) once every five years B) once every two years C) once every year D) once every six months E) only as necessary when the unit fails
C) once every year
Match the type of maintenance of a low water fuel cutoff for a steam boiler with its required frequency:
A) daily. 1) routine checks for leaks and abnormal conditions
B) weekly. 2) draining of a float chamber while burner is in operation
C) monthly 3) tripping the boiler by shutting off water supply
D) annually 4) dismantling the device
A-1, B-2, C-3, D-4
The low water fuel cutoff:
A) shuts the water flow if the fuel pressure is low
B) shuts of the fuel if the water pressure is low
C) shuts off the fuel if the water level is too 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 too low
The low water cutoff 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
On some low water cutoff devices, a three wire Mercury switch is used instead of a two wire switch in order to:
A) cut the main power to the boiler controls
B) energize an audible alarm
C) start an auxiliary cooling fan
D) open a steam pressure relief valve
E) send a signal to the plant master
B) energize an audible alarm
During a programmed startup, 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) boiler steam pressure operating control switch is open
C) the pilot manual fuel valve is closed
With automatic oil fired boiler programming control, the normal firing period begins approximately: A) 10 seconds after pilot extinguishes B) 44 seconds after FD fan starts C) 47 seconds after prepurge D) 60 seconds after FD fan starts E) 75 seconds after FD fan starts
D) 60 seconds after FD fan starts
With automatic gas fired boiler programmed control, the normal firing period begins approximately: A) 105 seconds after FD fan starts B) 75 seconds after FD fan starts C) 60 seconds after FD fan starts D) 47 seconds after prepurge E) 10 seconds after pilot extinguishes
A) 105 seconds after FD fan starts
The last step in an automatic boiler programmed shutdown sequence is:
A) operating control switch contacts closing
B) main flame trial
C) post purge
D) timer shutdown
E) flame failure switch contacts opening
D) timer shutdown
The function of a programming control is to:
A) supervise feedwater supply to the boiler
B) regulate the fuel supply to the burner
C) regulate combustion controls during startup
D) control the boiler blowdown rate
E) regulate fuel, air, and water supply to the boiler
C) regulate combustion controls during startup
In a power plant, networking of computers is advantageous because:
A) operators can use any computer to regulate the process
B) shift operators can communicate with each other by email
C) computing power is distributed and the loss of one computer is less serious
D) complete control will be maintained during a power failure
E) viruses may be easily eradicated throughout the system
C) computing power is distributed and the loss of one computer is less serious
In computer terminology, "RAM" means: A) read alone memory B) random access memory C) read access memory D) random acting memory E) rear access module
B) random access memory
A mainframe computer’s primary function is:
A) word processing
B) to rapidly process large amounts of data
C) to coordinate the functions of many small PCs
D) to communicate with a host computer
E) simple graphics tasks
B) to rapidly process large amounts of data
The type of computer memory that cannot be changed by the operator is called: A) RAM B) CRT C) CPU D) ROM E) ISIS
D) ROM
A host computer in a power plant would most likely be a: A) notebook computer B) micro computer C) main frame computer D) mini computer E) hand held computer
D) mini computer
