Thermodynamics and Heat Transfer in Air Conditioning Systems, Exams of Power Plant Engineering

Download Thermodynamics and Heat Transfer in Air Conditioning Systems and more Exams Power Plant Engineering in PDF only on Docsity! 4 th Class Power Engineering Part B 1&2 Exam Questions with Answers. A prime mover is a) An electric motor b) A steam turbine c) A centrifugal pump d) An air compressor e) A boiler - ANS b Large power production plants tend to be of the thermal type because they can burn solid fuels and: a) They are the least expensive to build b) The noise level is much less than internal combustion Engines c) The heat cycle they use is the most efficient d) Solid fuels are the most plentiful and cheapest e) Require the least amount of manpower - ANS c Whenever feasibly possible, when checking bearings on running pieces of equipment it is wise to a) Check the oil quality leaving each b) Check the oil quantity leaving each c) Get accustomed to normal running temperature and Vibration by feel d) Smell the normal odors of the running bearing e) Observe the temperature on a thermometer - ANS c One of the first ways to detect a fault in a reciprocating Engine is a) By sound b) Temperature indication c) Performance efficiency d) By oil consumption e) By smell - ANS a A steam turbine's exhaust can often supply a process with Steam because a) Processes always require a lower steam pressure b) Processes never require the high steam temperatures P a g e 1 | 390 Turbines do c) Turbine exhaust steam is always dry and saturated d) It is free of oil e) The steam will be at a temperature above the initial Temperature - ANS d The exhaust steam from a steam turbine is more acceptable for process than the exhaust from a steam engine because a) It is much hotter b) It is easily controlled c) It is free of oil d) It is free of moisture e) It contains more condensate - ANS c Turbines often have segmental carbon ring sealing glands Which are held in place by a) Labyrinths b) Shrouding c) Drive screws d) Garter springs e) Thrust runners - ANS d A steam turbine should trip or shut down when normal Operating speed is exceeded by a) 250 RPM b) 3 to 5% c) 50 RPM d) 10 to 15% e) 25 RPM - ANS d Condensing turbines a) Are always impulse turbines b) Will have a vacuum in the last row of rotating blades c) Will use the condensate for heating d) Are very small units e) Cannot have counter-flow stages - ANS b Which turbine uses a condenser? a) Back pressure turbine b) A turbine exhausting to a vacuum c) A bleeder turbine exhausting at atmospheric pressure d) A non-condensing extraction turbine P a g e 2 | 390 e) Over speed trip - ANS e Turbine thrust bearings are fixed to the casing and prevent axial movement of the spindle by contacting a component on the shaft known as a a) Shaft sleeve b) Labyrinth c) Collar d) Shroud e) Diaphragm - ANS c Shaft sealing carbon glands are a) Lubricated by the main oil pump b) Limited to a temperature of 250 degrees C c) Replaced monthly due to erosion d) Self-lubricating e) Metal sprayed components - ANS d The great majority of steam turbine governing systems utilize the a) Hydraulic system principle b) Pneumatic system principle c) Mechanical centrifugal principle d) Lever principle e) bi-metal expansion principle - ANS c Reaction turbines a) Have bucket shaped blades b) Have a pressure drop through the moving and stationary blades c) Are used for high pressures only d) Have a pressure drop in the moving blades only e) Have little axial - ANS b Reaction turbines a) Have all of the steam pressure drop take place In the stationary nozzle b) Have a velocity increase in the fixed blading c) Are used for higher speed only d) Have a velocity decrease through the fixed blading e) Require little blade sealing - ANS d P a g e 5 | 390 In an impulse turbine a) The steam flow is reduced through the nozzles b) The steam pressure is reduced in the nozzles c) The steam pressure will drop across the blades d) The steam velocity is increased through the blades e) The exhaust steam is directed - ANS b The steam turbine that has a pressure drop across Every set of blades is the __________ turbine. a) double-stage impulse b) single-stage impulse c) Topping d) Back pressure e) Reaction - ANS e When starting a steam turbine it is customary practice to a) Analyze the oil for water prior to rolling b) Turn on all cooling water systems first c) Place the speed control system in service once the unit Is rolling d) Test the over-speed trip as soon as running speed is Attained e) Stop the auxiliary oil pump as soon as steam begins to Turn the unit - ANS d The average amount of water volume which evaporates from a cooling tower is a) 2% b) 10% c) 15% d) 5% e) 3.5% - ANS d Natural draft cooling towers operate most effectively in Large open spaces and a) Where wind is relatively constant b) Where relative humidity is high c) Where a large body of water is nearby d) Require a windbreak e) Must not be in direct sunlight - ANS a P a g e 6 | 390 Excessive wind velocity in a natural draft cooling tower may cause a) Louvers to become broken b) High water drift or losses c) Rotation reversal of the fan d) Over-cooling of the water e) under-cooling of the water - ANS b Compared to a cross flow tower, a counter flow tower A) is not as tall B) has much less capacity c) Requires less floor space d) Requires more fan power e) Has a higher pressure drop - ANS c Water contained in the air stream at the discharge of a Cooling tower is removed a) With centrifugal separators b) By a series of chevron dryers c) By refrigeration means d) By a series of baffles e) With drift eliminators - ANS e A cooling tower which requires neither fan nor fill is the a) Natural draft unit b) Counter flow induced unit c) Venture unit d) Cross flow unit e) Forced draft unit - ANS c A valve which prevents water flow over the fill of a tower During cold weather should not be closed until the Temperature reaches A) - 0.5 degrees C B) + 0.5 degrees C C) + 5 degrees C D) + 20 degrees C E) + 27 degrees C - ANS e To prevent cooling tower basin water from freezing during P a g e 7 | 390 d) 25% to 30% e) 25% to 50% - ANS d Early gas turbines were handicapped by a) Metal not being able to withstand high speed centrifugal forces b) The inability to get enough air into the combustion Chamber c) Metals not standing the high temperatures involved d) Their high operating speeds e) Their inadequate power capability - ANS c The temperature to which the air can be raised at the turbine inlet is a) An indication of a unit's power b) Directly related to the unit's size c) A function of the air compressor input d) An indication of the unit's efficiency e) Important for proper compressor performance - ANS d The output power of a gas turbine is directly related to the a) Mass of gas passing through the turbine per second b) Temperature at the turbine inlet c) Mass of the unit d) Slippage between the turbine and compressor e) Turbine exhaust temperature - ANS a The low installation cost of a gas turbine is A) due to cheap materials in the blades b) Due to short fuel lines c) Because no fuel pump is required d) Because no electrical wiring is required e) Because less auxiliary equipment is needed - ANS e Some of the characteristics which make the gas turbine a better choice over other prime movers are: A 1. Low maintenance B 2. Minimum cooling water C 3. High thermal efficiency D 4. Rapid start-up and loading - ANS bad P a g e 10 | 390 The air side of a gas turbine re-generator is located a) Before the compressor b) After the combustion chamber c) Between the turbine and combustion chamber d) Between the turbine and atmosphere E) Downstream of the compressor - ANS e A gas turbine performs most effectively if a) Lube oil is of the proper viscosity b) Cooling water temperature is kept low c) Ambient air temperature is high d) Ambient air temperature is low e) Loaded immediately after starting - ANS d A combined steam and gas turbine arrangement can be termed a) An ideal system b) A co-generation system c) A once through system d) Ideal relative to system efficiency e) A high capacity system - ANS b The purpose of a re-generator is a) To clean the exhaust gases b) To improve the efficiency of the turbine c) To increase the temperature in the combustion chamber d) To lower the temperature in the combustion chamber e) To recirculate the exhaust gases back through the compressor - ANS b In a compression ignition engine the fuel is ignited by a) An electric spark b) The compressed air temperature c) The atomized fuel d) A cross-combustor E) Compressed air pressure - ANS b Diesel engine governing is accomplished by a) Varying the fuel quality b) Carburetor P a g e 11 | 390 c) Varying the fuel quantity d) Fuel atomizing air quantity e) Fuel atomizing air pressure - ANS a The fuel for a diesel engine is a) Light fuel oil b) Vaporized by a carburetor c) Mechanically atomized by high pressure d) Atomized before the cylinder e) Mixed with air before the cylinder - ANS c Four-stroke cycle engine valves are a) Operated by cams b) Of the pressure differential variety c) A number of ports in the cylinder wall d) Often termed reed or channel valves e) Always open as the piston travels upwards - ANS a An engine which develops one power stroke with every other turn of the crankshaft is the a) Two stroke diesel engine b) Type which requires pre-mixing lube oil and fuel c) Four stroke natural gas engine d) V type engine e) External combustion unit - ANS c Four cycle engine lubrication is usually a) Forced by pump b) By gravity oilers c) By the scoop method d) By the dip tube method e) By grease fitting - ANS a An example of an engine which gives high torque at low speeds would be that of a A) chain saw b) Two cycle snowmobile c) Four stroke motocross motorcycle d) Two cycle lawnmower e) Two cycle transit bus - ANS c P a g e 12 | 390 b) 255 kappa c) 3,030 kappa d) 2,100 kappa e) 435 kappa - ANS d Reduction in sealing qualities between the piston rings and cylinder wall by the lube oil may be the result of a) Low cooling water temperature b) High lube oil viscosity c) High cooling water temperature d) High carbon residue of the lube oil e) Wrong fuel being used - ANS c A pump is capable of suction lift due to a) Its ability to convert kinetic energy into potential Energy b) The speed at which it operates c) Its input power d) Its size e) Atmospheric pressure - ANS e Centrifugal pumps do not develop good suction lift because a) Atmospheric pressure is usually too low b) The pumped medium relative density is too high c) Their internal component clearances are too high d) The speed is too low e) They favor pressure rather than volume - ANS c It is generally accurate to say that a) 9.8 kappa pressure results from every meter of water depth or height b) A water height or depth of 10.34 meters results in 1 kappa c) 1 kappa will result from a water head of 9.8 meters d) 10.21 kappa will result from 1 meter of static water head e) Atmospheric pressure has no bearing on static water head - ANS a Preferably, dynamic pumps should be located a) Directly under the liquid source when suction lift is Involved b) Above the liquid source when suction head is involved P a g e 15 | 390 c) Above the liquid source when suction lift is involved d) At the liquid source level when suction lift is involved e) Below the liquid source when suction head is involved - ANS e The vertical distance from the liquid surface up to the pump center-line plus the vertical distance from the pump Center-line up to the surface of the liquid in the discharge tank is a) Static discharge head b) Static suction head c) Suction lift d) Total discharge head e) Total static head - ANS e The difference between static suction head and static Discharge head is a) Total static head b) Static discharge head c) Static suction head d) Equivalent head e) Dynamic head - ANS a When a pump discharges into a vessel operating at 300 kappa, the 300 kappa is referred to as a) Dynamic head b) Equivalent head c) Discharge head d) Friction head e) Total head - ANS c The total static head of a pump a) Is the capacity of the pump? b) Is the difference between the static suction head and The static discharge head c) Is the discharge pressure in meters? d) Is all the parts of the pump casing e) Is the discharge head of the pump - ANS B? When a reciprocating pump discharges while its piston or Plunger moves in only one direction, it is termed a P a g e 16 | 390 a) Positive displacement unit b) Single acting unit c) Dynamic unit d) Double acting unit e) Duplex unit - ANS b Centrifugal pumps convert rotating mechanical energy into kinetic energy then a) Discharge the kinetic energy B) Back to mechanical energy c) Absorb the energy d) Into potential energy in the form of pressure e) Into centrifugal force - ANS d A hot water heating system circulator should a) Be directly coupled b) Have its own vibration-free base c) Be very quiet in operation d) Develop an extremely high differential pressure e) Not run continuously - ANS c The capacity of a centrifugal pump a) Varies with discharge pressure b) Can be altered by speed variation only c) Indicates that the unit is a positive displacement type d) Should be varied by suction valve manipulation e) Is fixed and can only be altered by changing the impeller - ANS a Centrifugal pump power requirements are decreased when a) Discharge pressure is decreased b) The liters moved per minute is decreased c) The casing pressure drops d) The discharge velocity is high e) The discharge head is at minimum - ANS a A rotary pump a) Is a variety of dynamic unit? b) Never has discharge pulsations c) Should be equipped with a relief valve d) Has the highest capacity of any pump P a g e 17 | 390 Or reduce the cavitation? a) Close the casing vent valve b) Open the vent valve and close the suction valve c) Partially close the suction valve d) Close the discharge valve e) Raise the suction pressure - ANS e A positive displacement stand by-pump will have a) The vent and drain valves open b) The suction valve closed and the discharge valve open c) The suction valve open and the discharge closed d) The suction valve open and the discharge valve open e) The suction valve and the discharge valves closed - ANS d b - ANS Pumps handling cryogenic materials operate a) As staged units b) At extremely low temperatures c) Nearly always as dynamic units d) As tandem units e) As high speed units a - ANS a circulating pump is usually a) Connected with some type of heat ex-changer system b) A once through device c) Mounted to the piping d) A small capacity unit e) A high head unit c - ANS A multi-stage pump would be used a) When the lift is great b) When a greater volume must be pumped c) When the head is great d) When the temperature of the water being pumped is high e) Whenever there is sufficient boiler room floor space b - ANS Turbine pumps are best suited for a) Low capacity low pressure service b) Low capacity high pressure service P a g e 20 | 390 c) High capacity high pressure service d) High capacity low pressure service e) Heavy viscous fluids a - ANS Pump wear rings are installed on an impeller by set screws, threading or a) Shrinking b) Welding c) Brazing d) Soldering e) Forging c - ANS Wear rings are usually constructed of a) Ceramics or aluminum b) Graphite or bronze c) Bronze or cast iron d) Steel or alloy steel E) wrought iron or pig iron e - ANS Wearing rings: a) 1. Are used on impellers b) 2. Are used on the casing c) 3. Give protection to the shaft d) 4. Reduce the maintenance cost of the pump e) 124 e - ANS A stuffing box: A) 1. Stops air leaking into the casing when the pressure is below atmospheric b) 2. Decreases leakage out of the casing when the pressure is above atmospheric c) 3. Is always supplied with a lantern ring D) 4. Is filled with packing e) 124 e - ANS Mechanical seals: A) 1. Are used where leakage is objectionable b) 2. Replace stuffing boxes c) 3. Provide a better deal than packing D) 4. Are less costly than stuffing boxes e) 123 e - ANS Compression type packing: P a g e 21 | 390 A) 1. Prevents air from entering the pump b) 2. Reduces the maintenance cost on pumps c) 3. Protects the shaft from scoring and corrosion D) 4. Is used with all mechanical seals e) 1&2 e - ANS Lantern rings: A) 1. Prevent liquid leakage from the pump b) 2. Are fed by a liquid c) 3. Provide a seal to prevent air from entering the pump D) 4. Are mostly used on high lift pumps e) 234 c - ANS the seal cage on the shaft of a centrifugal pump a) Holds the shaft packing against the shoulder of the stuffing box b) Assists in reducing shaft vibration c) Distributes sealing water to the packing d) Prevents water from leaking out of the pump casing e) Reduces suction pressure drop b - ANS the main advantage of a pump using a mechanical seal is a) Lower first cost b) Less maintenance c) Less lubrication d) Smaller shaft required e) Increases discharge pressure d - ANS A slight leakage is desired between the pump shaft and Packing of the majority of pumps in order to a) Prevent the ingress of atmospheric air b) Increase the pump capacity and efficiency c) Prevent wearing of the wear rings d) Lubricate the surfaces e) Prevent the pump from vapor locking b - ANS If a stuffing box is to prevent the ingress of air, it is Equipped with a) A vacuum breaker b) A seal cage c) A bushing P a g e 22 | 390 e - ANS When lubricating equipment, the operator should also check for: A) 1. Unusual machine noises b) 2. Unusual consumption of lubricant c) 3. Excessive heat in bearing housing D) 4. Excessive leakage of lubricant e) All of the above c - ANS Most pump failures, damage, or both occurs a) After about six months of continuous service b) Due to vapor-binding c) During initial start-up D) due to wrong rotation e) Because of inadequate operator training c - ANS When a pump is operating, your inspection should include the following: a) You must check the impeller b) You must be sure the suction valve is closed c) you should check the discharge pressure d) You must be sure the drain valve is open e) You should check the oil pressure e - ANS A plugged impeller symptom or result will be a) Air leaks in suction line and stuffing boxes b) Wrong direction of rotation c) Loss of prime d) An overheated stuffing box e) No liquid being delivered a - ANS if pump speed is too high a) The driver may be overloaded b) Discharge pressure will be below normal c) No liquid will be delivered d) The pump will lose its prime after starting e) There will be air or gas in the liquid d - ANS If a pump is running and has no discharge pressure, what will you do? a) Close the suction valve a little b) Open the lubrication valve c) Check the lubricant level P a g e 25 | 390 d) Check to see if the suction valve is open e) Close the discharge valve a - ANS you discover that your feed water pump is not delivering sufficient water. A possible cause is a) The impeller is plugged b) The suction lift is too low c) The discharge head is not high enough d) There is too much water in the pump e) The foot valve is fully open a - ANS compressed air machinery would most likely be used in a) Coal mines b) Residential garages c) Home furnace control systems d) Agricultural applications e) Tool and die shops d - ANS Compressed air tools tend to be a) Heavier than equivalent electrical tools b) Damaged by overloading c) Hot after prolonged operation d) More expensive than electrical tools e) Less compact than electrical tools a - ANS In a centrifugal compressor the kinetic energy is converted To potential energy in the A) volute, diffuser, or both b) Intercooler c) Diffuser only d) Compressor cavity e) Volute only d - ANS the compressor which would favor volume over pressure would be the a) Rotary lobe b) Screw c) Axial d) Centrifugal e) Sliding vane P a g e 26 | 390 b - ANS Positive displacement air compressor types are a) Centrifugal compressors b) Gear compressors c) Axial compressors d) Multi-stage centrifugal compressors e) Not capable of producing high discharge pressures b - ANS Single stage reciprocating air compressors a) Must have an air receiver b) Could be of the rotary type c) Do need an intercooler d) Could have two cylinders e) Have a smooth discharge delivery e - ANS A belt driven lubricator is very popular on a a) Reciprocating double acting unit b) Screw unit c) Rotary lobe unit d) Centrifugal unit e) Sliding vane unit b - ANS Higher gearing is commonly used on a) Rotary lobe units b) Screw units c) Sliding vane units d) Reciprocating units e) Centrifugal units a - ANS Relative to a dry-pipe fire system, an automatic air supply Shall be connected so that proper pressure can be maintained in each system, is a statement of the a) National Fire Protection Association Code b) Industrial Accident Prevention Association c) Canadian Standards Association d) Occupational Health and Safety e) Society of Municipal Fire Marshall's d - ANS In order to protect the driver, a start-stop air compressor P a g e 27 | 390 d - ANS Air receivers a) must have a gage glass b) must have a thermometer c) must have a high pressure alarm d) must have a safety valve e) must have a high water alarm a - ANS Relative to lubrication, one place where wear is beneficial is a) new Babbitt bearing surfaces which wear smooth b) on pump wear rings c) on the oil pump sealing surfaces d) on the cylinder walls of internal combustion engines e) in anti-friction bearings d - ANS The inter meshing of gear teeth is a place where lubrication a) corrosion reduction is very important b) friction reduction is very important c) sealing is very important d) shock absorption is very important e) temperature control is very important e - ANS The lubricant performs a number of functions. Indicate which of the following are the most important: a)1. reduce wear b)2. temperature control c)3. reduce corrosion d)4. reduce friction e) 1& 4 d - ANS A material which is commonly used as a solid lubricant is a) tallow b) molybdate sulphide c) lime d) molybdenum disulphide e) sodium carbonate e - ANS Grease is not a suitable lubricant a) if the atmosphere contains a lot of moisture P a g e 30 | 390 b) when the atmosphere is dusty c) if corrosion protection is desired during downtime d) in the food industry e) if a large amount of cooling is desired c - ANS A semi-solid lubricant: a) can only be used for high temperature services b) has a low viscosity c) is less likely to drip or splash from bearings d) has a low pour point e) is best suited for heat removal e - ANS Lubricant for an anti-friction bearing is a) mineral oil b) graphite c) calcium or lime base grease d) not required e) barium and lithium base grease d - ANS Which type of grease is the cheapest and most commonly used? a) lithium base b) teflon base c) paraffin base d) calcium base e) silicon base a - ANS The property of an oil which indicates its ability to support a load is a) viscosity b) viscosity index c) pour point d) floc point e) consistency a - ANS If an oil's viscosity changes much with little temperature change then it will have a a) low viscosity index b) high pour point c) high carbon residue d) high viscosity index P a g e 31 | 390 e) low pour point d - ANS Which of the following has the greatest effect on the viscosity of a lubrication oil? a) pressure b) load c) flow d) temperature e) speed d - ANS The resistance of a liquid to internal deformation or shear is known as: a) pour point b) viscosity index c) flash point d) viscosity e) friction resistance a - ANS Which type of oil produces higher fluid friction? a) a high viscosity oil b) a low viscosity oil c) a low viscosity oil with a high flash point d) synthetic oils e) all mineral oils a - ANS Oil additives a) should not affect all other characteristics greatly b) will always affect the pour point greatly c) should be used as little as possible d) are not a component of most lube oils e) never lose their effect during use of the oil b - ANS If you desire an oil to flow at a much lower temperature you would most likely add a) a viscosity index improver b) pour point depressants c) a dispersant d) a thickening agent e) low viscosity oil P a g e 32 | 390 c) flotation type d) Kings-bury type e) vertical type b - ANS One of the main functions of the lubricant in a sealed, grease type anti friction bearing is a) wear reduction b) sealing c) shock absorption d) cooling e) surface separation e - ANS A journal bearing a) controls thrust movement b) does not require lubrication c) improves suction pressure d) does not require a housing e) supports a shaft d - ANS Thrust bearings: 1. are used on reaction turbines 2. prevent the turbine rotor moving axially 3. are always installed on both ends of the rotor shaft 4. are lubricated with the same oil as the main bearings a) 1,2 b) 3,5 c) 1,2,4 d) 1,2,4 e, 2,3,4 c - ANS The lubricant for an anti-friction bearing a) will separate the moving parts completely b) must be cooled c) could be a semi-solid lubricant d) prevents axial trust e) should have a high viscosity b - ANS A collar thrust bearing: 1. can support more load than a Michel thrust bearing P a g e 35 | 390 2. can prevent a rotating shaft from moving in both axial directions 3. has boundary lubrication 4. is an anti-friction type bearing a) 1,2 b) 2,3 c) 3,4 d) 2,4 e) 3,4 b - ANS A thrust bearing a) prevents radial movement of the shaft b) prevents axial movement of the shaft c) must be installed on both ends of the shaft d) has a volute casing e) should rotate opposite to the shaft a - ANS An anti-friction bearing a) could be a thrust bearing b) is a bearing containing white-metal alloy c) is a sleeve bearing d) receives larger amounts of oil e) cannot operate in an oil bath e - ANS A collar thrust bearing a) must have a shiny surface b) can support more load than a michell thrust bearing c) is an anti-friction type bearing d) is used with steam turbines only e) has boundary lubrication c - ANS A type of anti-friction bearing is the __________ bearing. a) spiral b) elliptical c) ball d) sleeve e) journal c - ANS Using pressurized air to blow out a cleaned bearing a) should only be done when ventilation is maximum P a g e 36 | 390 b) must be done only while the bearing is hot c) will cause the bearing to become "pitted" d) requires high pressure air e) can not cause damage to or affect our skin in any way a - ANS When replacing or removing an anti friction ball bearing, the applied force should a) not be transmitted through the bearing balls b) always be against the inner race c) always be against the outer race d) be applied suddenly and fully e) be made only after heating the bearing e - ANS Applying installation forces through the balls of a bearing can cause a) bearing misalignment b) false brinelling c) cracking or breaking of the balls d) improper lubrication e) brinelling d - ANS A normal anti-friction bearing temperature operating range is a) 150 to 160 degrees C b) 120 to 250 degrees C c) 20 to 50 degrees C d) 65 to 70 degrees C e) 80 to 120 degrees C b - ANS When grease is used in an anti-friction bearing, the bearing housing should not be filled more than _______full. a) 1/4 b) 1/3 c) 1/2 d) 3/4 e) completely e - ANS Causes of anti-friction bearing failures are: 1. improper fitting 2. false brinelling 3. high operating temperature P a g e 37 | 390 d) Ampere e) Electron e - ANS Atoms that have greater numbers of electrons in the outer shell are: Choose one answer. a. Positively charged b. Good conductors c. Poor insulators d. Neutrally charged e. Poor conductors b - ANS Electrons are negatively charged particles a) flowing through the atoms center b) orbiting about the nucleus of an atom c) firmly attached to the neutrons of an atom d) which can easily flow through insulators e) which seek open circuits e - ANS _____________ current flow is from positive to negative. a) Reversed b) Generated c) Static d) Conventional e) Electron a - ANS If an electrical ____ is placed across a conductor, the electrons will drift from the negative end towards the positive end of the conductor, assuming the electron theory. a) potential b) current c) resistance d) wire e) meter b - ANS A material that conducts electrical current is called a) a volt b) a conductor c) a circuit d) an electromotive force e) a conduit P a g e 40 | 390 a - ANS The electrical pressure that causes current flow through a circuit is a) electromotive force b) very high voltage c) the ohm d) the watt e) amperage d - ANS The flow of electrons in a uniform direction from atom to atom through a circuit, is known as a) electromotive force b) potential difference c) a short circuit d) current e) voltage drop e - ANS An insulator is material that will not _electrical current. a) reduce b) retard c) resist d) slow e) conduct e - ANS A closed electrical circuit will a) not allow current to flow b) contain an open switch or relay contact c) be series only d) be parallel only e) allow current to flow d - ANS An electrical device which is designed to start and stop current flow is the a) potentiometer b) fuse c) circuit breaker d) switch e) resistor a - ANS Ohms Law can be stated as P a g e 41 | 390 a) E = IR b) R = I/E c) I = R/E d) volts equals ohms divided by amperes e) watts times ohms equals volts c - ANS The voltage drop across a 20 ohm resistor with 10 amps flowing would be a) 2 b) 0.5 c) 200 d) 20 e) 150 c - ANS In an equivalent circuit developed from a multi-resistor series circuit a) the resistance will be the reciprocal sum of the original resistances b) voltage drop will be the same as for each of the original resistances c) the sum of voltage drops across the original resistances will be equal to the voltage drop of the equivalent circuit d) original circuit resistances will each have to be the same as the equivalent resistance e) amperage flowing will be different than the original circuit amperage flowing through each resistance a - ANS Three resistances of 20, 50 and 80 ohms make up a series circuit. Supply voltage is 400. The current flowing would be a) 2.67 amps b) 20 amps c) 8 amps d) 5 amps e) 60 amps b - ANS Equivalent resistance is decreased a) when voltage is decreased b) when a circuit is in parallel c) if the amperage is increased d) when a circuit is in series P a g e 42 | 390 a - ANS Most conductors tend to a) increase in resistance with increase in temperature b) decrease in resistance with increase in temperature c) shrink when heated d) melt when voltage is applied e) oscillate when voltage is applied d - ANS If the applied voltage in a circuit is 120 volts and the current flow is 3 amperes the resistance of this circuit is r = volts/amperes a) 40 Watts b) .025 Ohms c) 360 Ohms d) 40 Ohms e) 25 Watts c - ANS Voltage is a) the rate of current flow b) the rate of electron flow c) electromotive force d) the rate of Ohm flow e) required for current resistance a - ANS Electromotive force a) is capable of moving a quantity of electrons at some rate per period of time b) is able to move ohms through a resistance c) is increased by a resistor d) is increased by a voltage drop e) induces resistance to an open circuit c - ANS An ampere is the ___ of current flow. a) cause b) resistance c) measurement d) cause of reduction e) cause of increase P a g e 45 | 390 e - ANS ____ is an electromotive force. a) Amperage b) The ohm c) Power d) The watt e) The volt b - ANS Under normal circumstances, the heat produced by the electrical wires of a circuit is very small due to the a) large diameter of the conductor b) low resistance of the conductor c) long length of the conductor d) insulation wrapped around e) small diameter of the conductor b - ANS The unit of current flow is the a) watt b) ampere c) ohm d) volt e) hertz a - ANS The opposition a device or material offers to the flow of electric current, is known as: a) a resistance b) a short circuit c) a voltage drop d) an insulator e) counter flow d - ANS What power is dissipated by a resistor with a supply voltage of 120 volts and current of 8 amperes? P= V x A a) 960 ohms b) 15 ohms c) 15 watts d) 960 watts e) 96 kilowatts a - ANS Electrical power can be determined by the formula P a g e 46 | 390 a) P = IE b) I = ER c) E = IR d) R = EI e) P = IR b - ANS The basic unit of mechanical or electric power is the a) volt b) watt c) ampere d) ohm e) Newton e - ANS The voltage required to be supplied to a 12 kW motor drawing 24 amperes is a) 5 kilovolts b) 50 kilovolts c) 288 volts d) 2 kilovolts e) 500 volts d - ANS If the power dissipated by a resistor is 1.2 kW when supplied with 110 volts, the amperage will be a) 91.666 amperes b) 1320 amperes c) 19.006 amperes d) 10.909 amperes e) 132 amperes b - ANS Neglecting the efficiency of a 15 kW motor connected to a 400 volt supply, the amperage will be a) 26.667 amperes b) 37.5 amperes c) .0375 amperes d) 3.75 amperes e) 2.667 amperes d - ANS The watt is an electrical unit of measure for a) resistance P a g e 47 | 390 e) form a solenoid a - ANS If two unlike poles are placed adjacent to each other there is a) a force of repulsion between the magnets b) a development of iron filings between the magnets c) a reversal of the north and south poles of each magnet d) a force of attraction between the magnets e) a production of AC power e - ANS When current flows in a conductor a) A.C. voltage is generated b) the voltage is reduced in the conductor c) no heat can be generated d) all magnetic forces are dissipated e) a circular magnetic field is set up around the conductor c - ANS The total number of lines of force per square meter in a magnetic field is a) known as the EMF b) controlled by varying the temperature c) called the magnetic flux d) determined by the north magnetic pole e) depends on the force of gravity d - ANS Magnetic field direction and intensity depend on the a) temperature of the EMF b) EMF of the magnet c) copper content of the magnet d) direction and intensity of current flow e) specific heat of the conductor a - ANS When like poles of a magnet are placed adjacent to each other they will a) be attracted to each other b) bend c) increase in temperature d) repel each other e) have no reaction P a g e 50 | 390 e - ANS A property of a magnet is that it will always point in the north and south direction, when a) submerged in oil b) charged with electricity c) it is demagnetized d) in the presence of iron filings e) freely suspended in the air d - ANS Iron and steel may be magnetized by rubbing the metal with a) stainless steel b) steel wool c) a brass rod d) a magnet e) an iron filing compound e - ANS The property which determines whether or not a material will be easily magnetized or not is called a) reaction b) conductivity c) fluctuation d) magnetism e) permeability b - ANS The property of resistance to conducting magnetic lines of force is known as a) resistance b) reluctance c) impedance d) repulsion e) voltage drop c - ANS The maximum voltage generated by a single loop DC generator occurs when the conductor is cutting the magnetic lines of force at an angle of a) zero degrees b) 45 degrees c) 90 degrees d) 120 degrees e) 180 degrees d - ANS When using Fleming's Left Hand Rule, the index finger P a g e 51 | 390 represents a) generator action flux direction b) motor action motion direction c) generator conductor motion direction d) motor action flux direction e) motor action direction of current flow e - ANS A current carrying conductor being moved by a magnetic field is the principle known as a) magnetic flux b) electrolysis c) hydro-electrics d) generator action e) motor action a - ANS The direction of the ______________ due to motor action may be determined using the Left Hand Rule. a) force b) current c) resistance d) rotation e) applied voltage d - ANS The minimum voltage generated by a single loop DC generator occurs when the conductor is cutting the magnetic lines of forces at an angle of a) 45 degrees b) 90 degrees c) 120 degrees d) 180 degrees e) 270 degrees b - ANS The right hand rule is used to a) indicate the speed of a rotor b) determine the direction of induced current flow c) determine the frequency of an alternator d) determine the direction of motor rotation e) determine magnetic flux rotation d - ANS Batteries P a g e 52 | 390 d) indicates the amperage being drawn e) must be manually reset c - ANS A power meter a) reads the actual power consumed b) does not require a multiplying factor c) reads only a small percentage of the actual load d) will calculate the actual cost of the power e) does not take into account the system voltage c - ANS The electromagnetic field for a DC machine is termed the a) armature b) yoke c) field poles d) brush gear e) commutator d - ANS There are three main types of DC generators; series, shunt and compound wound. Each is a) separately excited b) capable of constant voltage regardless of load c) not excited by load current d) self-excited e) supplied with DC from batteries e - ANS Alternators must run at constant speed in order to maintain a) current b) power c) voltage d) resistance e) frequency a - ANS The output voltage of a shunt dc generator may be varied by adjusting the a) field rheostat b) brakes c) output current d) number of poles e) main breaker disconnect P a g e 55 | 390 b - ANS The main components of a DC machine are the yoke or frame which supports the ____and the rotor which is called an armature. a) wiring b) field poles c) rheostat d) fuse box e) generator a - ANS In order to produce the strength of magnetic flux required in larger DC machines a) electromagnets are used b) copper switches are used c) permanent magnets are used d) the field windings are double wound e) booster transformers are used e - ANS The armature core of a DC machine is built up of lamination's of a) copper bars b) mica sheets c) reinforced carbon plates d) electromagnets e) silicon steel plates b - ANS A shunt type DC generator has __________ output voltage. a) very high b) nearly constant c) very low d) erratic e) smooth b - ANS A shunt type DC generator has __________ output voltage. a) very high b) nearly constant c) very low d) erratic e) smooth e - ANS The magnetic field in a DC machine may be supplied by permanent magnets in small units. Large DC machines use field poles that are essentially P a g e 56 | 390 a) insulators b) resistors c) non-magnetic d) flux resistant e) electromagnets a - ANS The three main types of DC generators are the: 1. compound wound 2. parallel wound 3. series wound 4. reverse wound 5. shunt wound a) 1, 3, 5 b) 1, 2, 4 c) 2, 3, 5 d) 3, 4, 5 e) 2, 4, 5 d - ANS The load current has no effect on the field excitation of a a) compound wound generator b) series wound generator c) shunt wound generator d) separately excited generator e) reverse wound exciter b - ANS Three factors which control the electromotive force developed by a DC generator are the: 1. size of the frame 2. speed with which conductors cut the magnetic lines of force 3. number of conductors cutting the magnetic lines of force 4. diameter of the conductors 5. strength of the magnetic flux 6. diameter of the armature a) 1, 3, 6 b) 2, 3, 5 c) 2, 5, 6 d) 1, 4, 6 e) 3, 4, 6 P a g e 57 | 390 d) power e) capacity c - ANS The field rheostat in a DC generator is used to adjust the _______________ of the motor. a) direction of rotation b) current c) output voltage d) torque e) slip e - ANS The coils or winding's on a DC machine armature, are placed in_____________ cut in the face of the armature. a) bars b) holes c) pairs d) sequence e) slots b - ANS The commutator of a DC machine is made of copper bars mounted in a) glass b) micanite c) steel plates d) fiber-glass e) carbon rings a - ANS The field rheostat changes the ________in a DC generator. a) output voltage b) input voltage c) output current d) input resistance e) horse power d - ANS A compound wound DC generator has a combination of shunt and___________________ characteristics, depending on the predominance of each type of winding. a) parallel b) resistive c) reverse wound P a g e 60 | 390 d) series e) AC b - ANS The strength of the magnetic field produced in a shunt wound generator a) is weak b) is fairly constant c) fluctuates d) is regulated by an external AC supply e) cannot be varied c - ANS A compound wound DC generator may have three characteristics which are a: 1. decreasing output voltage versus load 2. no amperage requirement 3. constant output voltage 4. supplementary AC requirement 5. rising output voltage versus load a) 1, 2, 4 b) 2, 3, 5 c) 1, 3, 5 d) 1, 4, 5 e) 2, 3, e - ANS The output voltage rises sharply from minimum load to full load conditions for DC wound generators, if constructed with one of the following systems: a) shunt b) compound c) parallel d) anti-friction bearing e) series d - ANS The rotating field of an alternator is obtained by exciting the winding's on the rotor with a) AC power b) stator current c) magnetic particles d) DC power e) carbon poles b - ANS The stator of an alternator is built of ________________ P a g e 61 | 390 mounted in a frame. a) copper alloys b) silicon steel c) carbon ring d) asbestos impregnated silver e) non-metallic materials d - ANS A 6 pole alternator producing 60 Hz power must turn at a) 1800 rpm b) 2400 rpm c) 1000 rpm d) 1200 rpm e) 600 rpm e - ANS Alternators are constructed to use slip rings made of brass or a) copper b) carbon c) mica d) silicon e) steel c - ANS The number of cycles per unit of time measured in Hz, is known as a) time delay b) commutation c) frequency d) alternation e) motor speed e - ANS ____ are used on motors and generators to set up a magnetic field. a) Insulated wires b) Transformers c) Carbon rings d) Mica strips e) Field poles d - ANS A rheostat is also known as a a) voltage regulator P a g e 62 | 390 a) stop b) make c) heat d) vary e) remove d - ANS Synchronous motors are used to a) start alternators b) reduce the power factor of a power system c) prevent the need for a DC source of power d) improve the power factor of a power system e) drive variable speed loads d - ANS To transfer the power to or from the rotor of alternators or some AC motors a) field poles are employed b) rheostats are used c) a commutator is used d) slip rings are employed e) anti-friction bearings are employed c - ANS Apparent power is the power a) used for the actual work b) generated by rotating equipment c) supplied by the utility d) caused by system capacitance e) resulting from system inductance a - ANS When AC action causes a counter current in a coil it is termed a) self inductance b) capacitance c) hysteresis d) current generation e) electromagnetic induction c - ANS When magnetic flux produced by one coil induces an EMF in a second coil it is called a) self inductance b) electromagnetic induction c) mutual inductance d) capacitive reactance P a g e 65 | 390 e) inductive reactance b - ANS A transformer works on the principle of a) reverse polarity b) magnetic induction c) DC power flowing in one direction d) straight polarity e) automatic induction e - ANS If Ep/Es = Np/Ns, the Ns will equal: Choose one answer. a. Ep/NpEs b. EpEs/Np c. NpEsEp d. NpEp/Es e. NpEs/E c - ANS Three major losses which occur in a transformer are iron losses, copper losses and a) cooling losses b) heat losses c) flux leakage d) capacitive losses e) inductive losses c - ANS Copper losses in a transformer are reduced by a) using fan cooling b) using oil cooling c) using larger diameter wire d) reducing the primary voltage e) increasing the secondary voltage d - ANS An active current transformer should never a) be inspected until properly grounded b) have its primary circuit opened c) produce excessively high voltages d) have its secondary circuit opened e) have its secondary connected to a meter P a g e 66 | 390 e - ANS A phenomena produced by electronic switch gear which can result in excessively high voltages in transformers are known as a) capacitive reactance b) inductive reactance c) phase lag d) reactive voltage losses e) harmonic distortion d - ANS A device used to change the voltage and current from one level to another, is known as a/an a) conductor b) resistor c) alternator d) transformer e) power booster c - ANS An instrument transformer used to measure voltage is called a) current transformer b) step down transformer c) potential transformer d) step up transformer e) resistance indicator e - ANS Transformers are rated in terms of: 1. Volt amperes 2. Kilowatts 3. Kilo volt amperes 4. Ohms a) 1, 2 b) 2, 4 c) 2, 3 d) 3, 4 e) 1, 3 a - ANS The capacity of a transformer can be increased by: 1. submerging the core and winding's in a tank of oil 2. submerging the core and winding's in a tank of water 3. forced air cooling the oil in a heat exchanger 4. wrapping the core with a thermal insulation P a g e 67 | 390 d. Electro-magnetic induction a - ANS In a dc circuit, self-inductance is __ when voltage is at maximum, while in a ac circuit self inductance is __ a. Not a factor, continually a factor b. Sometimes a factor, not a factor c. Continually a factor, not a factor d. Not a factor, sometimes a factor e - ANS If the number of secondary turns is greater than the number of primary turns in a transformer. This transformer is called? a) current transformer b) step down transformer c) potential transformer d) step up transformer e) resistance indicator b - ANS If the secondary voltage is smaller than primary voltage in a transformer. This transformer is called? a) current transformer b) step down transformer c) potential transformer d) step up transformer e) resistance indicator b - ANS Primary and secondary winding's are split into two equal parts, with one half of the primary and one half of the secondary wound on each of the two "legs" of the transformer. This transformer is called? a) current transformer b) core type transformer c) potential transformer d) shell type transformer e) resistance indicator d - ANS All of the primary and secondary is wound on the centre leg. This transformer is called? a) current transformer b) core type transformer c) potential transformer P a g e 70 | 390 d) shell type transformer e) resistance indicator e - ANS Iron loses in a transformer are caused by? a. Eddy currents b. Magnetic hysteresis c. Harmonic distortion d. All of the above e. A and B e - ANS Double-wound transformers can be connected as? a) current transformer b) core type transformer c) potential transformer d) shell type transformer e) Autotransformer a - ANS Which transformer is used to trap the harmonics on the primary winding's? a) k-type transformer b) core type transformer c) potential transformer d) shell type transformer e) Autotransformer c - ANS When magnetic flux produced by one coil induces an EMF in a second coil, it is called: Choose one answer. a. Self inductance b. Electromagnetic induction c. Mutual inductance d. Capacitive reactance e. Inductive reactance d - ANS Transformers should be inspected at least: Choose one answer. a. Quarterly b. Bi-annually c. Semi-annually d. Once or twice a year e. Every five years P a g e 71 | 390 c - ANS A typical extra low voltage device would be a a) toaster b) set of tree lights c) door bell d) dry cell battery charger e) night light c - ANS A prime factor in determining the voltage to be used in a circuit is a) transformer capacity b) peak demands c) degree of access to equipment d) the number of motors involved e) the resistance of the circuit b - ANS Low voltage systems may have an acceptable voltage variation of plus or minus a) 10% b) 5% c) 1.5% d) 7.5% e) 12.5% - ANS The ability of an electrical circuit to store a charge of electricity even after the circuit is opened is termed a) hysteresis b) grounding c) inductance d) reactance e) capacitance c - ANS When working with high voltage systems, the minimum distance of approach should be a) 1 meter b) 5 meters c) 2 meters d) 3 meters e) 0.5 meters P a g e 72 | 390 d - ANS 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 - ANS A control device which will change one form of energy into another form of energy is the a) controller b) logic device c) primary element d) transducer e) transmitter a - ANS A device which will cause a visible light signal to become an instrument analog signal is the a) photoelectric transducer b) transmitter c) controller d) final element e) current-to-pneumatic transducer b - ANS A "control" should be considered as a special device which a) sends or transmits a positive rather than negative signal b) tries to maintain a set point c) is a 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 c - ANS Automatic systems which can make decisions are termed a) annunciation systems b) indicating systems c) logic systems d) open loop systems e) go-go systems P a g e 75 | 390 e - ANS A device that converts the measurement of a sensing device into a signal, is a a) controller b) logic device c) primary element d) relay switch e) transmitter e - ANS A sensing element responds to the value of the Choose one answer. a. Controller b. Recorder c. Control valve d. Transducer e. Controlled variable c - ANS A process variable which is adjusted in order to maintain or achieve some desired value of another variable is termed the: Choose one answer. a. Process variable b. Final variable c. Manipulated variable d. Controlled variable e. Transmitting variable d - ANS A fire eye or flame scanner keeps the burner circuit energized as long as the burner flame is maintained. This is accomplished using a: Choose one answer. a. Control valve b. Recorder c. Thermocouple d. Photoelectric transducer e. Controller a - ANS A sensing element sends its signal to a: Choose one answer. a. Transmitter b. Controller c. Control valve P a g e 76 | 390 d. Recorder e. Process variable a - ANS Some of the components of an automatic control loop are a sensing element, a transmitter, a _____ and a control valve. Choose one answer. a. Controller b. Transformer c. Transducer d. Piping system e. Converter b - ANS The forms commonly used for power-plant equipment control include analog, digital, mechanical, pneumatic and: Choose one answer. a. Physical b. Electrical c. Manual d. Thermal e. Magnetic e - ANS A control loop controller: Choose one answer. a. Operates without a set point b. Sends a signal to a primary element c. Measures the manipulated variable value, eliminating the need of a primary element d. Eliminates all setpoint deviation e. Constantly compares input signals to the set point b - ANS Level, pressure, flow, temperature, composition, vibration, speed and clearance are all examples of: Choose one answer. a. Transmitters b. Process variables c. Sensing elements d. Disturbances e. Manipulated variables d - ANS An open loop control system requires: P a g e 77 | 390 e. Transmitting variable b - ANS Which one is NOT an advantage of Pneumatic Signals? a. They are simple and provide trouble free operation b. They can transmit over long distances c. Less expensive than electronic instruments d. Safe in operation c - ANS Which one is NOT an disadvantage of Pneumatic Signals? a. Always lag or delay in the signal b. Friction causes a decrease in the value of the signal c. More expensive than electronic instruments d. Cost of tubing is greater than electrical wiring e. Ensuring a clean, dry air supply may be costly. a - ANS 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 d - ANS A Bourbon tube is often in the shape of a spiral so that a) its final output has less travel b) gears can be used for final output c) higher pressures can be sensed d) more power and travel of the output occurs e) its sensitivity will be decreased c - ANS When a diaphragm device is used for boiler water level measurement, the boiler pressure is compensated for or off-set by a) using a bellows on the HP side 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 P a g e 80 | 390 e - ANS One of the most widely used process variables in a system a) temperature b) pressure c) density d) purity e) flow c - ANS In a glass stem thermometer the space above the liquid is usually a) nitrogen b) argon c) maximum vacuum d) partial vacuum e) approximately 50% air d - ANS A thermocouple will produce a DC millivoltage which a) will be read on a pressure scale b) will be fully proportional to a temperature difference c) increases as temperature decreases d) is not quite proportional to temperature differences e) varies inversely with temperature e - ANS The Bourbon tube is often shaped in the form of a "C", having an arc span of about a) 180 degrees b) 360 degrees c) 200 degrees d) 90 degrees e) 270 degrees b - ANS The purpose of a spiral or a helix Bourdon tube is a) to increase the pressure rating b) to provide a greater degree of rotation c) to decrease the degree of rotation d) to decrease the linear motion e) to reduce fluttering of the indicator needle c - ANS Glass thermometers with a mercury fill are sometimes pressurized with nitrogen so P a g e 81 | 390 a) that they can be used in a horizontal position b) that they can be used at a very low temperature c) that they can be used at higher temperatures d) the vaporizing temperature of the mercury is lowered e) the mercury level is suppressed e - ANS Temperatures are measured by a) watt meters b) bourdon tubes c) thermowells d) pressure differential e) thermocouples d - ANS The variable area meter consists of 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 tube which is of constant area d) a tapered tube in which the fluid being measured flows through the tube from the bottom to the top e) an opening that can be varied as required e - ANS A bi-metal thermostat reacts to changes of a) pressure b) flow c) humidity d) heat e) temperature b - ANS When a float is used for measuring level, and installation within a vessel is impractical, a device often used is the a) float manometer b) float cage c) differential head meter d) diaphragm level indicator e) head transmitter d - ANS Relative to flow, velocity is kinetic energy and when velocity increases, the a) pressure and potential energy, will also increase P a g e 82 | 390 a. Will measure pressure in MPa b. Can only be used with mercury c. Is more accurate than the "U" tube manometer d. Has two furnace connections e. Is more difficult to read than the U-tube manometer e - ANS The Bourdon tube is often shaped in the form of a "C", having an arc span of about: Choose one answer. a. 180 degrees b. 360 degrees c. 200 degrees d. 90 degrees e. 270 degrees a - ANS The advantage of using a venturi tube, rather than an orifice plate for flow measurement is it: Choose one answer. a. Produces less permanent pressure drop b. Costs less to install c. Requires only one pressure tap d. Is less bulky e. Is flexible d - ANS Liquids must be vapourized Choose one answer. 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 e. When resistance or reluctance is being measured d - ANS Low pressures and vacuums may be measured: Choose one answer. a. With a transducer b. With a rotameter c. In MPa d. With a manometer e. In milli-Newtons P a g e 85 | 390 b - ANS A flapper-nozzle assembly is basic to all a) controllers b) transmitters c) recorders d) pneumatic devices e) actuators c - ANS In a glass stem thermometer the space above the liquid is usually: Choose one answer. a. Filled with Nitrogen b. Filled with Argon c. Under a vacuum d. Open to atmosphere e. filled with alcohol a - ANS The output pressure signal of a transmitter relay is usually a) direct and proportional to nozzle pressure b) a function of supply pressure c) inversely proportional to nozzle pressure d) fed to a final element of a loop e) the same as the primary element output signal a - ANS A two-position controller compares conditions to a set point and a) will start or stop a process b) desired value c) will modulate the final element d) can automatically readjust the set point e) will maintain final element position at 50% e - ANS When controller output is proportional to the amount of deviation, the controller is a) derivative only b) integral c) two-position d) proportion plus reset plus rate e) proportional b - ANS A proportional only controller P a g e 86 | 390 a) cannot maintain maximum value of the final element b) cannot maintain set point except at 50% 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 - ANS 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 of 0 to 24 hours e) range of 0 to 7 days d - ANS When a recorder receives a signal from a transmitter, the recorder incorporates a a) signal reverser b) pneumatic relay c) flapper-nozzle assembly d) capsule or bellows e) transducer a - ANS When an operator uses CRT displays, the computer control panel a) often has a number of dedicated recorders b) will be equipped with graph limiters c) will not have printout capabilities d) has only single trend display e) will not be connected to the transmitter signal c - ANS In a pneumatic control system, the nozzle receives a regulated air supply pressure of approximately: Choose one answer. a. 140 psi b. 20 kPa c. 140 kPa d. 210 kPa e. 30 kPa b - ANS A control valve P a g e 87 | 390 e. Is typically used for a feedwater control valve a - ANS A CRT trend display: Choose one answer. a. Mimics a trend chart. b. Is dedicated to a single process. c. Is limited to displaying a fixed or nonadjustable time period. d. Allows a view of only one process variable at a time. e. Is normally mounted beside the final control element. a - ANS a A CRT or LCD display trend recorder Choose one answer. a. Often has a number of dedicated displays b. Is equipped with graph limiters c. Does not have print out capabilities d. Displays only a single trend at a time e. Is independent of the transmitter signal a - ANS A sensing element sends its signal to Choose one answer. a. a Transmitter b. an air line c. a Conveyer d. a Flapper and nozzle e. a Recorder c - ANS A circular chart recorder: Choose one answer. a. Provides a different function than a strip chart. b. Is newer 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. e - ANS Cascade control utilizes: Choose one answer. a. One controller, one transmitter and two valves. b. One controller, two transmitters and two valves c. Two controllers, one transmitter and two valves. P a g e 90 | 390 d. Two controllers, two transmitters and two valves. e. Two controllers, two transmitters and one valve. d - ANS Most solenoid valves operate so that the upstream line pressure will: Choose one answer. a. Act to open the valve b. Be less than downstream pressure c. Be sensed by a transmitter d. Act to close the valve e. Must pass through a restriction or nozzle d - ANS A proportional-only controller: Choose one answer. 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. e. Are sometimes called Multi-position controllers a - ANS A valve which gives good throttling action, takes less actuator force, but does not seal well is a: Choose one answer. a. Double seated valve b. Reverse acting valve c. Multiple-disc valve d. Single seated valve e. Direct acting valve a - ANS Putting a controller on manual control means: Choose one answer. 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 e. The automatic controls have failed. b - ANS On a packaged boiler a number of electrical switches connected in series can be categorized as P a g e 91 | 390 a) controls b) interlocks c) start-up devices d) programmer controls e) detectors d - ANS A combustion air proving switch a) senses O content of the air 2 b) senses flue gas pressure c) detects O in flue gas 2 d) senses wind box pressure e) senses air temperature a - ANS A lead sulfide cell is sensitive to IR rays and a) its resistance to current flow varies inversely with ray emissions b) its resistance to current does not change during operation c) will not sense steady IR rays, only pulsating ones d) will not respond to glowing hot refractory e) must be replaced at least monthly c - ANS To operate the type of flame failure device which incorporates a lead sulphide cell, it must receive a) heat from flame b) ultraviolet rays c) infrared rays d) heat and radiation e) a digital signal b - ANS The function of a flame failure device is to a) shut off the fuel supply when the pressure gets too high b) shut off the fuel when the burner flame goes out c) shut off the fuel when the fuel temperature is high d) shut off the feed-water supply to the boiler P a g e 92 | 390 b) feedwater flow c) boiler water level d) fuel flow e) feedwater pressure e - ANS A packaged steam boiler modulating combustion control system will routinely a) maintain drum level within a desired range b) maintain flue gas temperature at some set point c) alter fuel flow without changing the air flow d) satisfy all load demands regardless of capacity e) maintain boiler steam pressure within a desired range a - ANS Modulating combustion control will a) change air and fuel flow proportionally to steam pressure change b) always be at set point when demand is at 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 - ANS An automatic boiler On-Off or operating control switch has an adjustment for pressure set-point and another for: Choose one answer. a. A differential between the two b. Manual or automatic control c. For rate of modulation d. High steam pressure limit e. Rate of feedback b - ANS Modulating pressure control a) will shut down and start up 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 - ANS Modulating combustion controls: Choose one answer. P a g e 95 | 390 a. Regulate the steam and feed water supply b. Regulate the fuel and air supplies c. Modulate only the fuel flow, because air flow is kept at maximum throughout the firing range. d. Are found only on the smallest of boilers e. Operate at either high or low fire c - ANS Modulating combustion control on a heating boiler is accomplished by a) shutting down or lighting up the burner as pressure or temperature rises or falls b) regulating the air flow to control combustion c) changing the amount of fuel and air to the burner d) opening or closing the forced draft damper e) regulating the fuel and feed water flow b - ANS Modulating pressure controller output: Choose one answer. a. Will shut down and start up the burner b. Will vary the fuel and air flow to the boiler c. Will control the temperature of the furnace d. Is used on small boilers only e. Is unresponsive to steam flow. c - ANS The most reliable method of checking or testing a low water fuel cutoff is to: Choose one answer. a. Blow the low water cutoff down through the water column until the burner cuts out. 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 down the sight glass to see if the burner goes out. e. Manually trip the mercury switches to shut off the burner. c - ANS A float operated level control: Choose one answer. a. Will recognize swell and shrinkage and correct the feed water flow b. Will have the float in the boiler drum c. Is only used on small boilers d. Is used on fire tube boilers only e. Must be used when a boiler is manually operated P a g e 96 | 390 c - ANS A float operated low water fuel cutoff has its switch separated from boiler pressure by: Choose one answer. a. A float cage b. A seal cage c. A flexible diaphragm d. A siphon e. Packing d - ANS In a float type low water fuel cutoff, the main purpose of the mercury switch is to: Choose one answer. a. Open the burner circuit when the level is high b. Close the burner circuit when the level is low c. Activate a low water alarm d. Open the burner circuit when the level is low e. Close the burner circuit when the level is high c - ANS A thermo hydraulic feed water regulator uses _____ as operating media. Choose one answer. a. Oil and nitrogen b. CO2 and water c. Water and steam d. Mercury and water e. Air and water b - ANS A mercury switch bulb is under high vacuum and contains inert gas: Choose one answer. a. So it will not explode b. To prevent corrosion of the contacts c. To decrease electrical resistance d. So contacts will not overheat e. Because the switch is normally closed e - ANS The type of combustion fuel control frequently used on small package boilers, is a/an: Choose one answer. a. Scanner b. Modulating control P a g e 97 | 390