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16 October 2023

[Solved Paper] AC Plant Operator previous question Paper 276/2022| 148/2023 Answer Key


[Solved Paper] AC Plant Operator previous question Paper  276/2022| 148/2023 Answer Key


Question Paper Code: 148/2023/OL

Category Code: 276/2022

Exam: AC Plant Operator

Date of Test 08-09-2023

Department Kerala State Film Development Corporation Ltd

AC Plant Operator previous question Paper  276/2022

Question1:-Which one of the following statement is not include the category of

general safety?

(i)   Keep the floor and gang ways clean and clear

(ii)   Move with care in the workshop, do not run

(iii)   Cut the hair short

(iv)   Don't walk under suspended loads

        A:-Only (iii)

        B:-Only (i) and (ii)

        C:-Only (iv)

        D:-All of the above

        Correct Answer:- Option-A

Question2:-Which one of the following statement is correct about the electrical


(i)   Only qualified persons should do electrical work

(ii)   keep the workshop floor clean, and tools in good condition

(iii)   Do not work on live circuits if unavoidable, Use rubber gloves rubber mats etc

(iv)   All of the above

        A:-Only (i), (ii) and (iii)

        B:-Only (iv)

        C:-Only (ii)

        D:-Only (ii) and (iii)

        Correct Answer:- Option-B

Question3:-Which one of the following statement is not true about the scriber?

(i)   In layout work it is necessary to scribe lines to indicate the dimensions of the

workpiece to be filed or machined

(ii)   It is made of high carbon steel and hardened

(iii)   It is used for scribing circles arcs and for transferring and stepping distances

(iv)   For drawing clear and sharplines, the point should be ground and honed

frequently for maintaining its sharpness

        A:-Only (i)

        B:-Only (ii)

        C:-Only (iii)

        D:-Only (iv)

        Correct Answer:- Option-C

Question4:-Which one of the following statement is not correct of an Engineering's


(i)   Hammer is a hand tool used for striking purposes while punching, bending

straightening, chipping forging or rivetting

(ii)   The major parts of a hammer are the head and the handle

(iii)   Hammer is made of drop forged carbon steel

(iv)   An Engineer's hammers are specified by their Length

        A:-Only (i) and (ii)

        B:-Only (ii) and (iii)

        C:-Only (iv)

        D:-Only (ii)

        Correct Answer:- Option-C

Question5:-Which statement is correct about the outside micrometer

(i)   It is a precision instrument used to measure a job within an accuracy of 0.01


(ii)   The micrometer works on the principle of screw and nut

(iii)   The ratchet stop of a micrometer is to ensure that a uniform pressure between

the measuring surfaces

(iv)   All of the above

        A:-Only (iv)

        B:-Only (i) and (ii)

        C:-Only (i)

        D:-Only (i) and (iii)

        Correct Answer:- Option-A

Question6:-Which one of the following statement is wrong about half moon stake?

(i)   It has a sharp head in the form of an arc of a circle

(ii)   This is used when shaping and seaming funnels and tapered articles

(iii)   This stake has bevelled along one side

(iv)   It is used for turning up flanges on metal discs

        A:-Only (i)

        B:-Only (i) and (ii)

        C:-Only (ii)

        D:-Only (ii) and (iv)

        Correct Answer:- Option-C

Question7:-Which of the following statement is correct about "Dolly"?

(i)   Used to support the head of the rivet which is already formed

(ii)   Used to form the final shape of the rivet during riveting

(iii)   Used for bringing the sheet metal closely together after inserting the rivet in

the hole

(iv)   Used for pressing the surface of the edge of the plate

        A:-Only (i)

        B:-Only (ii)

        C:-Only (iii)

        D:-Only (iv)

        Correct Answer:- Option-A

Question8:-Which of the following statement is correct for Oxy-acetylene gas


(i)    It is used only for brazing silver soldering and underwater gas cutting of steel

(ii)   Used for welding all ferrous and non ferrous metals and their alloys

(iii)   It has carbon and moisture effect

(iv)   It is used for heating

        A:-Only (i) and (ii)

        B:-Only (ii)

        C:-Only (iv)

        D:-Only (i) and (iv)

        Correct Answer:- Option-B

Question9:-Which of the following Hand tools are used by welders during welding


(i)   Double ended spanner

(ii)   Chipping Hammer

(iii) Tongs

(iv)   All of the above

        A:-Only (iv)

        B:-Only (ii) and (iii)

        C:-Only (i)

        D:-Only (i) and (ii)

        Correct Answer:- Option-A

Question10:-What is the effect of opened resistor in series electrical circuit?

        A:-No effect in opened resistor

        B:-Total supply voltage will appear across the opened resistor

        C:-No voltage will appear across the opened resistor

        D:-Fill circuit current will flow in opened resistor

        Correct Answer:- Option-B

Question11:-What is the minimum thickness of copper plate earth electrode?

        A:-3.25 mm

        B:-6.3 mm

        C:-6.5 mm

        D:-3.15 mm

        Correct Answer:- Option-D

Question12:-Which type of damping method is used in PMMC instruments?

        A:-Air friction damping

        B:-Gravity control damping

        C:-Spring control damping

        D:-Eddy current damping

        Correct Answer:- Option-D

Question13:-Which speed is called as synchronous speed in 3 phase induction


        A:-No load speed

        B:-Full load speed

        C:-Rotating magnetic field speed

        D:-Relative speed between stator and rotor

        Correct Answer:- Option-C

Question14:-Which type of conductor bar is used in the inner cage of double

squirrel cage induction motor?





        Correct Answer:- Option-B

Question15:-What is the application of shaded pole motor?

        A:-Hard disk drive

        B:-Ceiling fan

        C:-Wet grinder

        D:-Hair dryere

        Correct Answer:- Option-D

Question16:-Which type of starter is used to start and run the 3 phase slip ring

induction motor?

        A:-Direct on-line starter

        B:-Rotor resistance starter

        C:-Auto transformer starter

        D:-Manual star-delta starter

        Correct Answer:- Option-B

Question17:-What is the function of timer in automatic star delta starter?

        A:-Trip at over load

        B:-Switch ON at pre set time

        C:-Switch OFF at pre set time

        D:-Change from star to delta

        Correct Answer:- Option-D

Question18:-Which doping material is used to make P-type semi conductor?





        Correct Answer:- Option-A

Question19:-What is the main application of uni junction transistor?



        C:-Regulator circuits

        D:-Triggering circuits

        Correct Answer:- Option-D

Question20:-What is the unit of heat in M.K.S.system?





        Correct Answer:- Option-D

Question21:-Which special tool is using to measure the size of a capillary tube?


        B:-Steel rule

        C:-Capillary plug gauge

        D:-Torque wrench

        Correct Answer:- Option-C

Question22:-Using an anemometer we can measure the air velocity. What is the

unit of air velocity in the options given below?





        Correct Answer:- Option-A

Question23:-A ______ is used where the tightness of nut and bolts is a crucial

parameter of assembly or adjustment

        A:-Ring spanner

        B:-Torque wrench

        C:-Adjustable spanner

        D:-Box spanner set

        Correct Answer:- Option-B

Question24:-The _____________ of a substance is the ratio of the density of the

substance to the density of water at 4 degree celsius.

        A:-Specific volume

        B:-Specific heat

        C:-Specific gravity

        D:-Specific density

        Correct Answer:- Option-C

Question25:-Which of the given term is also known as the "total heat content" in

the measurement of heat contained in a sustance?

        A:-Specific heat



        D:-Latent heat of fusion

        Correct Answer:- Option-C

Question26:-The rate at which heat flows a substance to another is known as

        A:-Heat transfer coefficient

        B:-Overall conductance factor

        C:-U factor of the heat transfer surface

        D:-All of the above

        Correct Answer:- Option-D

Question27:-Which gas law give us the relation between pressure (P) and Volume

(V) w hen temperature (T) is kept constant?

        A:-Boyles Law

        B:-Charles Law

        C:-Regnaults Law

        D:-Gay Lusacs Law

        Correct Answer:- Option-A

Question28:-What is the boiling point of pure water in Kelvin scale?

        A:-100 degree celcius

        B:-212 degree Fahrenheit

        C:-273 degree Kelvin

        D:-373 degree Kelvin

        Correct Answer:- Option-D

Question29:-Which refrigeration system is also known as expandable refrigerant

refrigeration system

        A:-Vapour compression system

        B:-Liquid gas refrigeration system

        C:-Vapour absorption system

        D:-Dry Ice refrigeration system

        Correct Answer:- Option-B

Question30:-In dry ice refrigeration system, which of the following is used to cool

the materials?

        A:-Solid carbon dioxide

        B:-Liquid Nitrogen


        D:-Lithium Bromide solution

        Correct Answer:- Option-A

Question31:-In lithium bromide absorption refrigeration system, which of the

following is used as refrigerant




        D:-Lithium Bromide salt solution

        Correct Answer:- Option-B

Question32:-Which of the following compressor has the least volumetric efficiency?





        Correct Answer:- Option-A

Question33:-Why the rotary compressors are used as a vacuum pump?

        A:-No clearance volume

        B:-Less noice

        C:-Less power consumption

        D:-Lubrication not required

        Correct Answer:- Option-A

Question34:-Which of the following compressor uses whirl vein mechanism for

controlling capacity?





        Correct Answer:- Option-D

Question35:-The ratio of absolute discharge pressure to absolute suction pressure is

known as?

        A:-Volumetric efficiency

        B:-Mechanical efficiency

        C:-Compression ratio

        D:-Efficiency ratio

        Correct Answer:- Option-C

Question36:-Which valves are used to perform pump down operation in a domestic

air conditioning system?

        A:-Check valves

        B:-Service valves

        C:-Solenoid valves

        D:-Gate valves

        Correct Answer:- Option-B

Question37:-The capacity of a condenser is expressed in





        Correct Answer:- Option-D

Question38:-What is the reason for scale formation in shell and tube condenser?

        A:-Fouling in the condenser

        B:-Algae in the water

        C:-Power failure

        D:-Dissolved chemical and salts in the water

        Correct Answer:- Option-D

Question39:-The type of heat removal takes place when changes the refrigerant

vapour to liquid in water cooled condenser?

        A:-Latent heat of fusion

        B:-Latent heat of vaporization

        C:-Latent heat of condensation

        D:-Sensible heat of fusion

        Correct Answer:- Option-C

Question40:-The term indicates the difference in temperatures of inlet and outlet of

cooling tower water is known as



        C:-Cooling tower efficiency

        D:-Set point

        Correct Answer:- Option-B

Question41:-During the operation of a cooling tower, the air takes away the fine

droplets of water from cooling tower. Which term is used to denote this?

        A:-Blow down loss

        B:-Drift loss

        C:-Spill loss

        D:-Evaporation loss

        Correct Answer:- Option-B

Question42:-What is the lowest temperature of water is achieved in cooling tower?

        A:-Wet bulb temperature of air

        B:-Dew point temperature of air

        C:-Dry bulb temperature of air

        D:-Dry saturation temperature of air

        Correct Answer:- Option-A

Question43:-Which expansion valve's operation is controlled by a microprocessor?

        A:-Automatic expansion valve

        B:-Thermostatic expansion valve

        C:-Electronic expansion valve

        D:-Dry saturation temperature of air

        Correct Answer:- Option-C

Question44:-Which of the following expansion valve is also known as "constant

pressure valve"

        A:-Automatic expansion valve

        B:-Thermostatic expansion valve

        C:-Electronic expansion valve

        D:-High side float valve

        Correct Answer:- Option-A

Question45:-In which line, the refrigerant control is fitted in the vapour compression


        A:-Discharge line

        B:-Suction line

        C:-Bypass line

        D:-Liquid line

        Correct Answer:- Option-D

Question46:-During evaporation the refrigerant absorbs heat from the

surroundings. What kind of heat is absorbed during evaporation?

        A:-Super heat

        B:-Sensible heat

        C:-Latent heat

        D:-Specific heat

        Correct Answer:- Option-C

Question47:-Which of the following operating temperature is true, related to the

operating condition of frosting type evaporator?

        A:-Above 273ºK

        B:-Below 32ºF

        C:-Below 100ºC

        D:-Below 0ºK

        Correct Answer:- Option-B

Question48:-In which of the following refrigerant group R-410A belongs to?



        C:-HFC Blend

        D:-Inorganic group

        Correct Answer:- Option-C

Question49:-Which of the following quality of refrigerant should be high?

        A:-Specific volume

        B:-Boiling point

        C:-Freezing point

        D:-Thermal conductivity

        Correct Answer:- Option-D

Question50:-In which year India aim to completely ban HCFC refrigerant?





        Correct Answer:- Option-B

Question51:-The GWP of refrigerant 1234yf is?





        Correct Answer:- Option-A

Question52:-The cylinder colour code of refrigerant 502 is?





        Correct Answer:- Option-B

Question53:-Refrigerator thermostat thermal bulb is clamped with?


        B:-Liquid line

        C:-Expansion valve


        Correct Answer:- Option-D

Question54:-The function of capillary tube in refrigerator is

        A:-Increase the pressure of refrigerant

        B:-Meters the refrigerant

        C:-Act as a receiver

        D:-Pumps the refrigerant

        Correct Answer:- Option-B

Question55:-Which type of condenser is equipped with refrigerator?

        A:-Plate type

        B:-Shell and tube

        C:-Shell and coil


        Correct Answer:- Option-A

Question56:-The reason for insufficient air throw in frost free refrigerator is

        A:-Compressor running in low speed

        B:-Thermostat is defective

        C:-Air distribution duct is partially chocked

        D:-Timer is defective

        Correct Answer:- Option-C

Question57:-What is the function of defrost timer in frost free refrigerator is?

        A:-Compressor running in low speed

        B:-Thermostat is defective

        C:-Air distribution duct is partially chocked

        D:-Timer is defective

        Correct Answer:- Option-C

Question58:-The frequency range maintained in inverter refrigerator is

        A:-40 Hz to 150 Hz

        B:-80 Hz to 190 Hz

        C:-20 Hz to 50 Hz

        D:-50 Hz to 80 Hz

        Correct Answer:- Option-A

Question59:-The temperature of water maintained in water cooler is?

        A:-60 to 65°F

        B:-10 to 20°F

        C:-45 to 50°F

        D:-30 to 40°F

        Correct Answer:- Option-C

Question60:-The recommended vacuum level should be maintained in water cooler

before charging is

        A:-500 microns

        B:-750 microns

        C:-1000 microns

        D:-150 microns

        Correct Answer:- Option-D

Question61:-The temperature range maintained in visible cooler is?

        A:-12 to 15°C

        B:-0 to 10°C

        C:--2 to 4°C

        D:--10 to 0°C

        Correct Answer:- Option-B

Question62:-Freezers are usually designed to operate a temperature range of?

        A:--15 to -35°F

        B:-0 to 10°C

        C:-0 to 2°C

        D:--15 to -34°C

        Correct Answer:- Option-D

Question63:-The type of evaporator generally used in deep freezer is?

        A:-Fin type

        B:-Wire mesh type

        C:-Plate type

        D:-None of the above

        Correct Answer:- Option-C

Question64:-What is the reason to form white milky ice in ice plant?

        A:-Presence of air

        B:-Presence of CO2

        C:-Presence of impurities

        D:-Presence of salt

        Correct Answer:- Option-A

Question65:-The safety device which is used to protect the compressor of window

air conditioner is?




        D:-None of these

        Correct Answer:- Option-B

Question66:-In summer air conditioning, the air is

        A:-Cooled and humidified

        B:-Cooled and dehumidified

        C:-Humidified and dehumidified

        D:-None of these

        Correct Answer:- Option-B

Question67:-What is the HP of a fan motor in window air conditioner of 1 ton?

        A:-1/4 HP

        B:-1/5 HP

        C:-1/6 HP

        D:-1/32 HP

        Correct Answer:- Option-C

Question68:-The capacity of stabilizer required for 1 ton air conditioner is?

        A:-5 KVA

        B:-1 KVA

        C:-4 KVA

        D:-3 KVA

        Correct Answer:- Option-D

Question69:-The thermostat sensing bulb of window air conditioner senses which


        A:-Condenser temperature

        B:-Supply air temperature

        C:-Return air temperature

        D:-Room outside air temperature

        Correct Answer:- Option-C

Question70:-What will happen when the thermostat cut down a split AC?

        A:-The compressor will stop

        B:-The condenser fan will stop

        C:-The compressor and condenser fan will stop

        D:-The compressor condenser fan and indoor blower will stop

        Correct Answer:- Option-C

Question71:-The cooling capacity of 1 Ton Air conditioner is?

        A:-18000 BTU/Hr

        B:-4500 Kilo calorie/Hr

        C:-5.25 KW

        D:-All of these

        Correct Answer:- Option-D

Question72:-What is the minimum quantity of gas required to be in R 407C charging

cylinder while gas charging AC?





        Correct Answer:- Option-A

Question73:-The air ducts can be balanced by?



        C:-Duct branches

        D:-None of these

        Correct Answer:- Option-A

Question74:-The device covert incoming alternating current to direct current in

inverter AC?




        D:-All of these

        Correct Answer:- Option-B

Question75:-What is the reason for excess cooling on ice cubes in an ice candy


        A:-More refrigerant charging

        B:-Thermostat not working

        C:-High atmospheric temperature

        D:-High compressor pressure

        Correct Answer:- Option-B

Question76:-Which instrument is used to check the specific gravity of brine solution

in ice plant?





        Correct Answer:- Option-B

Question77:-Why ammonia is used as a common refrigerant in an ice plant?

        A:-High vapour density

        B:-Low evaporator pressure

        C:-Low critical pressure

        D:-High latent heat value

        Correct Answer:- Option-D

Question78:-Which expansion device is used in walk in coolers?

        A:-Thermostatic expansion valve

        B:-High side float valve

        C:-Capillary tube

        D:-Low side float valve

        Correct Answer:- Option-A

Question79:-What is the reason for stop the compressor motor due to LP cut out

switch in cold storage plant?

        A:-High discharge pressure

        B:-High evaporator pressure

        C:-Low discharge pressure

        D:-Low evaporator pressure

        Correct Answer:- Option-D

Question80:-Which process will be done during hot gas defrosting?

        A:-Heater on

        B:-Expansion valve will close

        C:-Solenoid valve will close

        D:-Condenser fan motor stop

        Correct Answer:- Option-C

Question81:-In air blast freezing of food, the velocity of air varies from

        A:-30 to 120 m/min

        B:-18 to 30 m/min

        C:-10 to 25 m/min

        D:-6 to 12 m/min

        Correct Answer:- Option-A

Question82:-During sensible cooling of air in an air conditioning process, the

specific humidity will be


        B:-Remains constant



        Correct Answer:- Option-B

Question83:-The wet bulb depression indicates ________ humidity of the air?





        Correct Answer:- Option-D

Question84:-During adiabatic saturation process on unsaturated air ____________

remains constant?

        A:-Wet bulb temperature

        B:-Dry bulb temperature

        C:-Relative humidity

        D:-Dew point temperature

        Correct Answer:- Option-A

Question85:-The wet-bulb depression is zero when relative humidity is





        Correct Answer:- Option-D

Question86:-What is the advantage in central AC plant?

        A:-The room temperature is constant

        B:-The air supply is centralised

        C:-Initial expense in less

        D:-Energy efficiency high

        Correct Answer:- Option-B

Question87:-The aspect ratio, for rectangular ducts, should not be greater than

__________ in any case





        Correct Answer:- Option-C

Question88:-Which sensors measure the moisture level using humidity?

        A:-Resistive sensor

        B:-Capacitive sensor

        C:-Thermal sensor

        D:-Conductive sensor

        Correct Answer:- Option-B

Question89:-In package Air conditioner HP cut out is controlled by

        A:-High pressure of discharge

        B:-High pressure of suction

        C:-High temperature of suction

        D:-Pressure of liquid line

        Correct Answer:- Option-A

Question90:-What is the effect on adjusting the thermostat differential too close in

package A/C?

        A:-Normal cooling effect

        B:-Unit runs continuously

        C:-Unit does not start

        D:-Unit starts and stops frequently

        Correct Answer:- Option-D

Question91:-The location of thermostat sensing bulb in split package unit is

        A:-Return air duct

        B:-Liquid line

        C:-Suction line

        D:-Before the air filter

        Correct Answer:- Option-D

Question92:-A mixing box is an example of which kind of damper

        A:-A modulating damper

        B:-A manual damper

        C:-A two-position damper

        D:-A relief damper

        Correct Answer:- Option-A

Question93:-Air dampers used for HVAC service are

        A:-Parallel blade types only

        B:-Opposed blade types only

        C:-Single blade types only

        D:-Opposed blade, parallel blade, and single blade types

        Correct Answer:- Option-D

Question94:-Duct are usually of _____________ cross-section





        Correct Answer:- Option-B

Question95:-Which of the filter is having lowest contamination?

        A:-ULPA filters

        B:-HEPA filters

        C:-Both 1 and 2

        D:-Fiberglass filters

        Correct Answer:- Option-C

Question96:-The fibers media of HEPA filters usually have a diameter between

        A:-0.5 and 2.0 micrometers

        B:-10 and 100 micrometers

        C:-5 and 20 micrometers

        D:-0.1 and 2 micrometers

        Correct Answer:- Option-A

Question97:-Air filter in an A/C is used for cleaning of

        A:-Conditioned air blown into the room


        C:-Hot air thrown out from condenser side

        D:-Return air

        Correct Answer:- Option-D

Question98:-In auto mobile A/C operates on __________ principles?

        A:-Iso thermal

        B:-Thermo electric

        C:-Electro magnetism

        D:-Thermo dynamism

        Correct Answer:- Option-C

Question99:-Where the location of pressure operated hot gas BPV?

        A:-Between evaporator and suction line

        B:-Between compressor suction line and liquid line

        C:-Between compressor discharge and suction line


        Correct Answer:- Option-C

Question100:-How you can find gas leak by visual inspection in Bus A/C?

        A:-Oil trace by the union and connections

        B:-Check over bent

        C:-Trace the hole

        D:-Check gauge pressure

        Correct Answer:- Option-A


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