Quiz Questions

Question 1 1 Marks

What is the method of starting a 3 phase slip ring induction motor?

A

With starting relay

B

Using starting capacitor

C

With running capacitor

D

Adding resistance to rotor winding

Question 2 1 Marks

What is the atmospheric pressure at sea
level?

A

1.033 kg/cm2

B

1.3 Kg/cm2

C

1.5 Kg/cm2

D

1.6 Kg/cm2

Question 3 1 Marks

Which safety control is manually reset after rectifying the faults in packages AC?

A

LP

B

HP

C

OLP

D

OILP

Question 4 1 Marks

Which type of evaporator is used in frost free refrigerator?

A

Plate type

B

Wire mesh

C

Finned tube

D

Shell and tube

Question 5 1 Marks

What is the function of remote control in split AC?

A

Humidity setting

B

Pressure setting

C

Drain water control

D

Transmits signal to operate AC

Question 6 1 Marks

Why the idler pulley is used in belt driven car AC?

A

Decrease the belt vibration

B

Increase the belt tension

C

Increase the feathering

D

Decrease the belt tension

Question 7 1 Marks

Which component belongs to outdoor unit of split AC?

A

Blower

B

Air filter

C

Compressor

D

Evaporator coil

Question 8 1 Marks

What is the reason for switching contacts get carbonised in package AC electrical wiring?

A

Humidity

B

Quality is bad

C

Loose connections

D

Too tight connection contacts

Question 9 1 Marks

Which movement of plunger energises the start winding in relay operation?

A

Vertically up

B

Bottom side

C

Vertically down

D

Horizontally left

Question 10 1 Marks

Which two tubes act as heat exchanger in a refrigerator?

A

Suction and charging tube

B

Discharge and suction tube

C

Capillary and suction tube

D

Discharge and capillary tube

Question 11 1 Marks

Which sheet is used to check the tigtness of door gasket of a refrigerator?

A

Rubber

B

Plastic

C

Copper

D

Zinc

Question 12 1 Marks

What is the advantage of using flux in brazing?

A

Over heating

B

Melting tubes

C

Prevent Oxidation

D

Chemical reaction

Question 13 1 Marks

Which type of compressor is used in window air conditioner?

A

Belt drive

B

Open type

C

Sealed type

D

Swash plate

Question 14 1 Marks

What is top dead centre in reciprocating compressor cylinder?

A

The piston moves down from the point of cylinder

B

The piston moves up from the point of cylinder

C

The piston stops in cylinder at bottom

D

The piston starts in cylinder at bottom

Question 15 1 Marks

What is the temperature of air at the supply grille in car AC system at an ambient 35 Degree Centigrade?

A

10.2 Degree Centigrade

B

11.3 Degree Centigrade

C

12.4 Degree Centigrade

D

13.5 Degree Centigrade

Question 16 1 Marks

How the power consumed by the motor varies with its speed in VFD?

A

Cube of its speed

B

Square of its speed

C

No change with speed

D

Inversely proportional to its speed

Question 17 1 Marks

What is the advantage of using indirect expansion chiller AC system?

A

Quick cooling

B

Cooling tower is not needed

C

Less quantity of primary refrigerant

D

Less quantity of secondary refrigerant

Question 18 1 Marks

Which type of switch is used to control the room air temperature in split AC?

A

Over load protector

B

Thermostat switch

C

Manual switch

D

Thermal relay

Question 19 1 Marks

What is the purpose of relay used in window air conditioner?

A

Disconnect the starting capacitor

B

Disconnect the running capacitor

C

Disconnect the fan capacitor

D

Disconnect the winding

Question 20 1 Marks

Which valve is used for gas charging and pressure checking in central AC plants?

A

Safety valve

B

Service valve

C

Solenoid valve

D

Non return valve

Question 21 1 Marks

Which type fan blade is used with out door unit of split AC?

A

Vane

B

Guide vane

C

Propeller

D

Centrifugal

Question 22 1 Marks

Which instrument is used to measure the velocity pressure of air in ducting system?

A

Nanometer

B

Pitot tube

C

Barometer

D

Bourdeon tube

Question 23 1 Marks

Which capacitor is disconnected by relay in capacitor start and induction run motor?

A

Starting capacitor

B

Running capacitor

C

Boosting capacitor

D

Power factor correction capacitor

Question 24 1 Marks

What is the reason for intermittent cooling cycle in car AC?

A

Moisture in the system

B

Fully evacuated system

C

Excess of lubricant in receiver

D

Non condensables in the system

Question 25 1 Marks

How many fan motors are used in split AC?

A

Two

B

Five

C

Four

D

Three

Question 26 1 Marks

What is the effect of moist air present inside the hermetic system?

A

Capacity of compressor will increase

B

Less wear and tear in compressor

C

Harmful to the compressor and motor

D

Increase the life of compressor

Question 27 1 Marks

How many hydrogen atoms are present in R 134a?

A

One

B

Two

C

Four

D

Three

Question 28 1 Marks

What is the rate of doing work?

A

Duty

B

Force

C

Power

D

Velocity

Question 29 1 Marks

Which operation is carried out first in selector switch after installation of package AC?

A

Compressor 1

B

Compressor 2

C

Blower - low speed

D

Blower - high speed

Question 30 1 Marks

Which psychometric process takes place if the air is passed through hygroscopic chemicals?

A

Sensible heating of air

B

Heating and humidification

C

Heating and cleaning of air

D

Heating and dehumidification

Question 31 1 Marks

What is the equivalent absolute scale for centigrade?

A

Kelvin

B

Celsius

C

Rankine

D

Fahrenheit

Question 32 1 Marks

What is the name of electronic
circuit?

A

Bridge rectifier

B

Half wave rectifier

C

Full wave rectifier

D

Quarter wave rectifier

Question 33 1 Marks

Which type of fan blade is used with indoor unit?

A

Guide vane

B

Blower

C

Axial

D

Vane|

Question 34 1 Marks

Which type fan blade is used with out door unit of split AC?

A

Vane

B

Guide vane

C

Propeller

D

Centrifugal

Question 35 1 Marks

What is the function of remote control in split AC?

A

Humidity setting

B

Pressure setting

C

Drain water control

D

Transmits signal to operate AC

Question 36 1 Marks

Which motor has the least starting
torque?

A

CSIR

B

CSR

C

RSIR

D

PSC

Question 37 1 Marks

Which component switches ON/OFF the starting winding in RSIR motor?

A

Thermostat

B

Capacitor

C

Relay

D

OLP

Question 38 1 Marks

Which system maintains indoor air quality by adding fresh air and conditioned air to offset heating or cooling loads?

A

Refrigeration system

B

Air distribution system

C

Electrical control system

D

Refrigerant control system

Question 39 1 Marks

What is the ratio of oxygen to acetylene in neutral flame for brazing?

A

01:03

B

02:01

C

01:01

D

01:02

Question 40 1 Marks

Which is adjusted to the size of electrode in welding process?

A

Conductor

B

Thickness

C

Length

D

Ampere

Question 41 1 Marks

Which gauge is connected to the AC plant system before doing pump down operation?

A

Compound gauge

B

Oil pressure gauge

C

High pressure gauge

D

Water pressure gauge

Question 42 1 Marks

What is the pH level of water used for final
rinsing of condenser tubes after descaling?

A

4 to 4.5

B

7 to 7.5

C

10 to 12

D

9 to 10.5

Question 43 1 Marks

What is the remedy for defective heating element in a frost free refrigerator?

A

Repair heater

B

Readjust the heater

C

Replace heater and bimetal thermo

D

Reuse the heater and over load protector

Question 44 1 Marks

What is effect of compression process on refrigerant vapour?

A

Heat the vapour below saturation

B

Cool the vapour above saturation

C

Increase the pressure and temperature

D

Decrease the pressure and temperature

Question 45 1 Marks

What is the physical condition of refrigerant
in hermetic dome of rotary compressor?

A

LP Liquid

B

HP Liquid

C

HP Vapour

D

LP Vapour

Question 46 1 Marks

Why the acetylene gas is avoided with copper pipe lines or fittings in oxy-acetylene welding set?

A

Copper is expensive

B

Copper is not flexible hose

C

Copper and acetylene form explosive

D

Copper pipe consumes more acetylene

Question 47 1 Marks

What is the preventive remedy for scale in water cooled condenser tubes in package AC?

A

Install flow meter

B

Minimise water flow

C

Improve water quality

D

Increase water pressure

Question 48 1 Marks

How many fan motors are used in split AC?

A

Two

B

Five

C

Four

D

Three

Question 49 1 Marks

What is the function of starting capacitor in CSIR motor?

A

Gives initial torque

B

Gives running torque

C

Corrects power factor

D

Improves energy efficiency

Question 50 1 Marks

What is the reason for poor cooling effect in multi split air conditioner?

A

Efficient compressor

B

Proper condensation

C

Good insulation

D

Dirty air filter

Question 51 1 Marks

Which group the acetylene gas belongs?

A

HC

B

HFC

C

CFC

D

HCFC

Question 52 1 Marks

What is the purpose of chemical spraying on finned condenser?

A

Flush out the condenser tubes

B

Remove the rust on the fins

C

Blow the dust from the fins

D

Correct the bends in fins

Question 53 1 Marks

Which operating condition opens the HPC control switch in car AC?

A

If evaporator pressure exceeds safe limit

B

If there is continuous rain outside

C

If condenser pressure exceeds safe limit

D

If there is continuous air velocity

Question 54 1 Marks

Which design data is used for indoor air heating in winter air conditioning?

A

20Degree Centigrade +/- 1 Degree Centigrade and RH = 35%

B

18Degree Centigrade +/- 1 Degree Centigrade and RH = 45%

C

16Degree Centigrade +/- 1 Degree Centigrade and RH = 50%

D

14Degree Centigrade +/- 1 Degree Centigrade and RH = 55%

Question 55 1 Marks

What is the effect of residual acid particles after descaling the shell and tube condenser in industrial AC plant?

A

Block the strainer

B

Corrode the tubes

C

Reduce heat transfer

D

Increase algae growth

Question 56 1 Marks

What is the effect of scale formation inside the tubes of chiller in industrial AC plant?

A

Reduce heat transfer

B

Increase heat transfer

C

Increase suction pressure

D

Decrease power consumption

Question 57 1 Marks

Which controls the speed of blower fan motor to vary air cooling or heating in car AC?

A

Selector switch and resistors

B

Thermostat and return-air sensor

C

Ambient and cabinet temperature

D

Increase or decrease refrigerant flow

Question 58 1 Marks

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

A

B.T.U (British thermal unit)

B

K.Cal (Kilo Calorie)

C

KV (Kilo Volt)

D

K.W (Kilo Watt)

Question 59 1 Marks

What is the reason for swash plate compressor failure in car AC?

A

Oil level is low

B

Oil level is medium

C

Thermostat not working

D

Refrigerant charge normal

Question 60 1 Marks

Which two terminals read the highest resistance while testing refrigerator compressor motor?

A

Start and run

B

Common and run

C

Start and common

D

Start and compressor body

Question 61 1 Marks

What is the effect if the oil return from oil separator to the compressor is blocked?

A

Suction pressure rises

B

Discharge pressure decreases

C

Compressor oil level falls down

D

Compressor oil level increases

Question 62 1 Marks

What is the rotor speed with respect to stator field speed in an induction motor?

A

Less than the stator speed

B

More than the stator speed

C

Equal to the stator speed

D

More than the fly wheel

Question 63 1 Marks

What is the reason for filter drier sweating in refrigerator?

A

Nitrogen in the system

B

Moisture in the system

C

Oxygen in the system

D

Oil in the system

Question 64 1 Marks

What is the name of active component used in electronic circuit?

A

Transistor

B

TRIAC

C

DIAC

D

SCR

Question 65 1 Marks

What is the purpose of rinsing the condenser tubes with water after descaling process in industrial AC plant?

A

Remove algae

B

Remove scales

C

Check block in tubes

D

Remove acid particles

Question 66 1 Marks

Which device engages the compressor shaft in car AC?

A

Thermo switch

B

Car engine pulley

C

Over load protector

D

Electro magnetic clutch

Question 67 1 Marks

What is the use of magnetic clutch in Car AC?

A

Indicate liquid level in the compressor

B

Indicate oil level in the compressor

C

Control ON/OFF for compressor

D

Add oil in the system

Question 68 1 Marks

Which flame is used for welding brass?

A

Wide flame

B

Neutral flame

C

Oxidising flame

D

Carburising flame

Question 69 1 Marks

Which causes the clogged orifice in TEV of car AC system?

A

Nitrogen

B

Oxygen

C

Moisture

D

Non condensable gases

Question 70 1 Marks

What is applied to find the leakage on acetylene gas connection?

A

Soap bubbles

B

Halide torch

C

LPG torch

D

By smell

Question 71 1 Marks

Which tool is used for descaling the condenser tubes in shell and tube condenser?

A

Steel brush

B

Brass brush

C

Sponge brush

D

Teflon fibre brush

Question 72 1 Marks

Which expansion device is used with VFD motors in multi split AC?

A

Electronic

B

Automatic

C

Thermostatic

D

Hand operated

Question 73 1 Marks

What is the remedy to remove moisture from the window AC system?

A

Over gas charge in the system

B

Evacuate the system deeply

C

Clean the evaporator fins

D

Clean the condenser fins

Question 74 1 Marks

Which component belongs to indoor unit of split AC?

A

Compressor

B

Condenser

C

Evaporator

D

Drier

Question 75 1 Marks

How the brine freezing on cooling coil is prevented in ice plant?

A

Add water to brine

B

Add glycol to brine

C

Reduce concentration

D

Increase salt concentration

Question 76 1 Marks

What is the cause of water hammer or valve chatter in water pump lines?

A

Low pump pressure

B

Blocked suction line

C

High pump pressure

D

Low velocity of water

Question 77 1 Marks

Where the refrigerant is stored in split AC during pump down operation?

A

Accumulator

B

Compressor

C

Evaporator

D

Condenser

Question 78 1 Marks

What is the cooling capacity of 1 TR in K Cal / hr?

A

3000

B

4000

C

5000

D

6000

Question 79 1 Marks

What is the safety device used during arc welding?

A

Screw clamp

B

Hand screen

C

Electrode holder

D

Lugs for welding

Question 80 1 Marks

Which T across water tubes indicates the shell and tube condenser for decalling process?

A

2 Degree Centigrade

B

3 Degree Centigrade

C

4 Degree Centigrade

D

5 Degree Centigrade

Question 81 1 Marks

Which device is used to measure the
density of brine solution?

A

Lactometer

B

Hydrometer

C

Hygrometer

D

Thermometer

Question 82 1 Marks

Which valve helps to attend mechanical faults without wasting the gas in split AC?

A

Gate valve

B

Float valve

C

Service valve

D

Expansion valve

Question 83 1 Marks

What is the direction of airflow delivered in a centrifugal blower?

A

Parallel to the shaft

B

Perpendicular to the shaft

C

Inclined throw of air vertically

D

Inclined throw of air horizontally

Question 84 1 Marks

What is the use of suction baffle in a scroll compressor?

A

Reduce noise of compressor

B

Increase noise of compressor

C

Reduce capacity of compressor

D

Allow liquid to enter into compressor

Question 85 1 Marks

Which material is used for making fins of condenser in a window air conditioner?

A

Brass

B

Copper

C

Cast iron

D

Aluminium

Question 86 1 Marks

How the difference between the
synchronous speed and the actual rotor speed is
specified?

A

Lead

B

Lag

C

Slip

D

Trip

Question 87 1 Marks

What is the purpose of accumulator in a refrigerator?

A

Improves oil circulation

B

Prevents surging of refrigerant

C

Avoids hunting of refrigerant

D

Prevents liquid flood back to compressor

Question 88 1 Marks

What is the precautionary measure taken if flame snaps out and back fires?

A

Shut off both valve quickly and dip in water

B

Shut off oxygen first and acetylene next

C

Shut off acetylene first, oxygen next and dip in water

D

Shut off both valve, oxygen first and dip in water

Question 89 1 Marks

Which semiconductor material is used to make diodes?

A

Steel

B

Silicon

C

Copper

D

Aluminium

Question 90 1 Marks

What is the dew point depression of air if dry bulb and dew point temperatures are 36 Degree Centigrade and 32 Degree Centigrade respectively?

A

2 Degree Centigrade

B

4 Degree Centigrade

C

6 Degree Centigrade

D

8 Degree Centigrade

Question 91 1 Marks

What is the advantage of a hermetically sealed compressor in refrigerator?

A

Silent operation

B

Easily serviceable

C

Noise is more

D

Cost is high

Question 92 1 Marks

Which safety device is attached to nitrogen
cylinder?

A

Fuse plug

B

Compound gauge

C

Two stage pressure regulator

D

Automatic pressure bypass valve

Question 93 1 Marks

Which material is used to avoid oxidation between aluminium conductor and the terminal?

A

Petrol

B

Grease

C

Shellac

D

Kerosene

Question 94 1 Marks

What is the expansion of ADP?

A

Apparatus Dew Point

B

Advanced Detection Process

C

Advanced Distributor Process

D

Appliance Durability Promotion

Question 95 1 Marks

What is the absolute pressure of gas in a cylinder, if gauge reads 135.3 p.s.i?

A

130 p.s.i.a

B

140 p.s.i.a

C

150 p.s.i.a

D

160 p.s.i.a

Question 96 1 Marks

Where the refrigerant is stored in split AC during pump down operation?

A

Accumulator

B

Compressor

C

Evaporator

D

Condenser

Question 97 1 Marks

What is the cause for compressor cut off by HP cut out in package AC?

A

Aged wire

B

Compressor grounded

C

Cooling tower fan failure

D

Mild gas leak in evaporator

Question 98 1 Marks

Which tool is used for tightening the odd size bolts and nuts?

A

Socket set

B

Nose pliers

C

Ring spanner

D

Adjustable spanner

Question 99 1 Marks

Which switch is interlocked to become on if the power isolator is off in package AC?

A

Thermostat

B

Blower motor

C

Crankcase heater

D

Compressor starting

Question 100 1 Marks

What is the least count of a metric micrometer?

A

0.1 mm

B

0.01 mm

C

0.001 mm

D

000.1 mm

Question 101 1 Marks

What is the advantage of glass fibre ducting?

A

Economical

B

Heavy weight

C

Self insulating

D

High heat transfer

Question 102 1 Marks

What is the cooling capacity of 0.5 TR in BTU / hr?

A

6000

B

12000

C

18000

D

24000

Question 103 1 Marks

How much heat is released from 2 HP motor if 746 W motor releases 3 K Cal/hr?

A

3 K Cal/hr

B

4 K Cal/hr

C

5 K Cal/hr

D

6 K Cal/hr

Question 104 1 Marks

Which fan is used in condensing unit of ductable split air conditioner?

A

Forward curved fan

B

Centrifugal fan

C

Propeller fan

D

Radial fan

Question 105 1 Marks

What is the reason for high condensing pressure in air cooled condensers?

A

Dirt on fins

B

Faulty water pump

C

High speed of fan motor

D

Low ambient temperature

Question 106 1 Marks

What is the colour of acetylene hose pipe in oxy - acetylene welding set?

A

Maroon

B

Green

C

Black

D

Red

Question 107 1 Marks

Which type of rotor is used in 3 Phase induction motor?

A

Squirrel cage rotor

B

Shaded pole rotor

C

Laminated rotor

D

Solid rotor

Question 108 1 Marks

Which type of evaporator is used in window air conditioner?

A

Bare tube

B

Plate and tube

C

Fins and plate

D

Fins and tube

Question 109 1 Marks

Which component actuates the defrost cycle in frost free refrigerator?

A

Bimetal thermo

B

Defrost heater

C

Timer

D

Relay

Question 110 1 Marks

Which device meters the amount of refrigerant entering the evaporator in window AC?

A

Accumulator

B

Capillary tube

C

Heat exchanger

D

Finned tube condenser

Question 111 1 Marks

Which device protects the compressor motor from drawing more current?

A

OLP

B

Relay

C

Thermostat

D

Door switch

Question 112 1 Marks

How the reciprocal of air density is mentioned in psychrometric chart?

A

Specific gravity

B

Specific heat ratio

C

Sensible heat ratio

D

Specific volume per unit mass

Question 113 1 Marks

What is the ozone depleting potential of R 134a Refrigerant?

A

0

B

1

C

2

D

3

Question 114 1 Marks

Which part of window AC removes dust particles from the room air?

A

Strainer

B

Air filter

C

Filter drier

D

Dehydrator

Question 115 1 Marks

Which control trips if the expansion valve inlet strainer is blocked in chiller AC plant?

A

Thermostat control

B

Low pressure cut out

C

Oil pressure cut out

D

High pressure cut out

Question 116 1 Marks

What is the effect if the refrigeration system is started before chilled water pump?

A

No cooling

B

Water warms in chillier

C

Water freezes in chillier

D

Excess of heat transfer

Question 117 1 Marks

What is the value of starting capacitor used for 1TR window air conditioner?

A

40 MFD

B

60 MFD

C

80 MFD

D

100 MFD

Question 118 1 Marks

What are the active components used in electronic circuits?

A

Transformers and inductors

B

Transistors, diodes and SCRs

C

Semi conductors and transformers

D

Resistors, capacitors and inductors

Question 119 1 Marks

Which document is used for writing the AC system parameters round the clock?

A

Log sheet

B

Trip sheet

C

Note sheet

D

Plain sheet

Question 120 1 Marks

What is meant by hydronic system?

A

Pressure equaliser

B

Humidity control system

C

Pressure control system

D

Water distribution system in HVAC

Question 121 1 Marks

Which is used to connect the rotor bars in 3phase squirrel cage induction motor?

A

Screw

B

Welded

C

End ring

D

Nut and bolt

Question 122 1 Marks

Which material is used for making disc in energy meter?

A

Aluminium

B

Copper

C

Brass

D

Zinc

Question 123 1 Marks

Which instrument is used to measure the total pressure in an air duct?

A

Hygrometer

B

Velocimeter

C

Anemometer

D

Pitot tube manometer

Question 124 1 Marks

Which gas is used to flush out the coils of air cooled condenser?

A

Dry nitrogen

B

Pure dry air

C

Oxygen

D

kaksr

Question 125 1 Marks

What is the angle of the tip of centre punch?

A

30 Degree

B

60 Degree

C

90 Degree

D

120 Degree

Question 126 1 Marks

What is the maximum capacity of 3 phase squirrel cage induction motor used with direct on line (DOL) starter?

A

5 HP

B

10 HP

C

15 HP

D

20 HP

Question 127 1 Marks

What is the advantage of periodical cleaning of air filter?

A

Decrease the volume of air handling

B

Increase the speed of fan motor

C

Decrease the cooling capacity

D

Increase the cooling capacity

Question 128 1 Marks

Which international agency standardises the numbering system for identifying refrigerants?

A

ASHRAE

B

ISHRAE

C

DW142

D

ISO

Question 129 1 Marks

Which application uses the digital
ICs?

A

Amplifier

B

Logic gates

C

Tuned circuits

D

Voltage regulator

Question 130 1 Marks

Which domestic system uses automatic defrost?

A

Frost free refrigerator

B

Conventional refrigerator

C

Split air - conditioner

D

Window air - conditioner

Question 131 1 Marks

Which joint is made in either single or multi - strand conductors?

A

Rat tail joint

B

Scarfed joint

C

Britannia joint

D

Western union joint

Question 132 1 Marks

Which factors produce work?

A

Force and distance

B

Time and distance

C

Force and power

D

Force and time

Question 133 1 Marks

Which type of 1-? motor has high starting torque?

A

Permanent capacitor

B

Resistance start induction run

C

Capacitor start and capacitor run

D

Induction start and induction run

Question 134 1 Marks

What is the melting temperature of silver
brazing rod?

A

1120 Degree F

B

1200 Degree F

C

1250 Degree F

D

1300 Degree F

Question 135 1 Marks

What are the causes for blockage in
capillary tube?

A

Non condensable gases

B

Moisture and wax from oil

C

Solid particles

D

Over charging of refrigerant

Question 136 1 Marks

What is the cooling capacity for 1.5 Ton of ductable split air conditioner?

A

3500 Kcal/hr

B

4000 Kcal/hr

C

4500 Kcal/hr

D

5000 Kcal/hr

Question 137 1 Marks

How much volume of oxygen is needed for complete combustion of one unit volume of acetylene?

A

1.5 times

B

2.5 times

C

3.5 times

D

4.5 times

Question 138 1 Marks

Which winding is made of thin wire in single phase motor?

A

Main

B

Series

C

Starting

D

Running

Question 139 1 Marks

Which material is used for making ICs?

A

Silicon

B

Carbon

C

Platinum

D

Mild steel

Question 140 1 Marks

Which material is used to clean oil and grease on the floor?

A

Cotton waste

B

Saw dust

C

Water

D

Air

Question 141 1 Marks

Which part of electronic filter removes tobacco smoke and odours?

A

Pre filter

B

Electrodes

C

Charcoal filter

D

Static electric field

Question 142 1 Marks

Which instrument is used to identify the
terminals of a compressor motor?

A

Ammeter

B

Voltmeter

C

Ohm meter

D

Anemometer

Question 143 1 Marks

What is the cause for frequent tripping of circuit breaker while starting a single phase motor?

A

Winding open

B

Winding short

C

Motor belt removed

D

No load on the motor

Question 144 1 Marks

Where the normally closed contacts are internally connected in voltage relay?

A

Across 1 and 5

B

Across 2 and 5

C

Across 1 and 2

D

Across 2 and 4

Question 145 1 Marks

Which part of the refrigerator cools the liquid refrigerant in capillary tube?

A

Discharge line

B

Suction line

C

Condenser

D

Evaporator

Question 146 1 Marks

What is the remedy for noisy blower with excessive axial play in AHU?

A

Apply grease

B

Change belts

C

Replace blower unit

D

Change the air filter

Question 147 1 Marks

Which atmospheric standard air is used in calculating air velocity?

A

23 Degree Centigrade and 760 mm

B

22 Degree Centigrade and 760 mm

C

21 Degree Centigrade and 760 mm

D

20 Degree Centigrade and 760 mm

Question 148 1 Marks

Which type of short cycling is avoided by the design of blower housing in car AC?

A

Oil

B

Air

C

Moisture

D

Lubricant

Question 149 1 Marks

What is the effect of increased out door temperature in car AC?

A

Compressor runs more time

B

Compressor runs less time

C

Performance remains the same

D

Performance increases

Question 150 1 Marks

Which type of drier filter is suitable for HFC refrigerants?

A

Molecular sieve type

B

Activated alumina

C

Activated carbon

D

Silica gel

Question 151 1 Marks

Which type of rotor is used in split phase induction motor?

A

Wound coil

B

Eccentric

C

Squirrel cage

D

Permanent magnet

Question 152 1 Marks

Which compressor capacity is suitable for 2 TR air conditioner?

A

3000 Kcal/h

B

4000 Kcal/h

C

5000 Kcal/h

D

6000 Kcal/h

Question 153 1 Marks

What is the absolute zero temperature in
degree centigrade?

A

0 Degree Centigrade

B

100 Degree Centigrade

C

-273 Degree Centigrade

D

212 Degree Centigrade

Question 154 1 Marks

Which parameter indicates that the central AC system has non condensable gas?

A

Liquid line temperature

B

Pressure drop in discharge line

C

Condenser inlet water temperature

D

Condenser outlet water temperature

Question 155 1 Marks

What is the purpose of TEV in refrigeration cycle of package AC?

A

Condensing gas

B

Throttling refrigerant

C

Flush out dry nitrogen

D

Cooling the evaporator

Question 156 1 Marks

Which AC connects the indoor evaporator unit with outdoor condenser unit through a wall hole of 7cm diameter?

A

Split air-conditioner

B

Window air-conditioner

C

Central air-conditioner

D

Industrial air-conditioner

Question 157 1 Marks

Which type of condenser is used in window air conditioner?

A

Fins and tube

B

Plate and tube

C

Plate and coil

D

Bare tube

Question 158 1 Marks

What is the human body temperature in Degree Centigrade?

A

17 Degree Centigrade

B

27 Degree Centigrade

C

37 Degree Centigrade

D

47 Degree Centigrade

Question 159 1 Marks

What is the remedy for insufficient cool supply air from package AC?

A

Check for gas leak

B

Repair the compressor

C

Flush out the condenser

D

Replace the blower belt

Question 160 1 Marks

What is the remedy for no lubrication even if the sight glass shows proper oil level?

A

Replace oil pump

B

Add oil to crankcase

C

Replace oil pressure gauge

D

Replace oil pressure cut out

Question 161 1 Marks

Which type of condenser is directly placed on water spray and air?

A

Shell and tube condenser

B

Water cooled condenser

C

Evaporative condenser

D

Air cooled condenser

Question 162 1 Marks

Which type of condenser is used in window Air conditioner?

A

Natural convection

B

Forced convection

C

Water cooled

D

Evaporative

Question 163 1 Marks

Which is scheduled for yearly maintenance in package AC?

A

Wash the air filter

B

Tighten the blower belt

C

Clean the cooling tower

D

Tighten the pump gland nut

Question 164 1 Marks

Why the crankcase heater is energised for compressor during the shut down period of AC plant?

A

Increase viscosity of crankcase oil

B

Decrease viscosity of crankcase oil

C

Increase miscibility of oil with refrigerant

D

Prevent oil foaming on restarting compressor

Question 165 1 Marks

How to safe guard the hands while handling glass wool?

A

Wearing goggles

B

Wearing gloves

C

Using mask

D

Using shoes

Question 166 1 Marks

Which component is connected in series with bimetal thermo in a frost free refrigerator?

A

Blower

B

Door switch

C

Cabinet bulb

D

Defrost heater

Question 167 1 Marks

Why the glass wool insulation is avoided in ducts?

A

Less strength

B

High conductivity

C

Not resistant to water

D

Allows vapour transmission

Question 168 1 Marks

Which parameter of power supply reduces the starting current in VFD motor?

A

Decreased power factor

B

Increased supply voltage

C

Lower frequency operation

D

Decreased resistance mode

Question 169 1 Marks

Which type of expansion device is used in flooded chillers?

A

Float valve

B

Multiple capillary

C

Automatic expansion valve

D

Hand operated expansion valve

Question 170 1 Marks

How the capacity of refrigerator is expressed?

A

Weightage

B

Tonnage

C

Wattage

D

Litres

Question 171 1 Marks

Which schedule is followed for lubricating the cooling tower fan motor in package AC?

A

Daily

B

Weekly

C

Biweekly

D

Quarterly

Question 172 1 Marks

Where the refrigerant vapour is compressed in scroll compressor?

A

Fixed and reciprocating scroll

B

Between fixed and orbiting scrolls

C

Crank and connecting rod

D

Eccentric and cylinder

Question 173 1 Marks

What is the name of heat carrying medium in vapour compression system?

A

Air

B

Water

C

Liquid

D

Refrigerant

Question 174 1 Marks

How numerical designations of inorganic refrigerants are assigned?

A

Divide 700 to molecular mass of compound

B

Multiply 700 to molecular mass of compound

C

Adding 700 to molecular mass of compound

D

Subtracting 700 from molecular mass of compound

Question 175 1 Marks

Which instrument is used to measure pressure on both high and low side of the system?

A

Pipe manifold

B

Gauge manifold

C

Pressure manifold

D

Instrument manifold

Question 176 1 Marks

Which type of fan blade is used with indoor unit?

A

Guide vane

B

Blower

C

Axial

D

Vane|

Question 177 1 Marks

What is the advantage of periodical cleaning of air filter?

A

Decrease the volume of air handling

B

Increase the speed of fan motor

C

Decrease the cooling capacity

D

Increase the cooling capacity

Question 178 1 Marks

What is the value of absolute vacuum in millimeters of mercury?

A

-76

B

-760

C

-14.7

D

-10.33

Question 179 1 Marks

What is the category of R 502 refrigerant?

A

Azeotropes

B

Halocarbon

C

Hydrocarbon

D

Organic compounds

Question 180 1 Marks

Which insulating material is poured as liquid?

A

Glass Wool

B

Cork Board

C

Wood Shave

D

Poly Urethane Foam (PUF)

Question 181 1 Marks

Which temperatures are marked on 100% RH curve?

A

Air and water

B

Wet-bulb and dew point

C

Critical and condensing

D

Evaporating and condensing

Question 182 1 Marks

Which process is done first in split AC for shifting from one place to another?

A

Flushing

B

Evacuation

C

Pump down

D

Vacuumisation

Question 183 1 Marks

Which component is used in frost free refrigerator?

A

Plate coil evaporator

B

Liquid receiver

C

Oil separator

D

Timer switch

Question 184 1 Marks

What is the weld test without destroying or breaking the joint?

A

Destructive test

B

Non destructive test

C

Radio graphic test

D

Magnetic test

Question 185 1 Marks

Which psychrometer uses battery operated small fan?

A

Sling psychrometer

B

Aspirating psychrometer

C

Laboratory psychrometer

D

Exhausting psychrometer

Question 186 1 Marks

Which safety switch deactivates the compressor motor circuit if suction pressure falls below the safe limit in package AC?

A

Selector switch

B

Low pressure switch

C

High pressure switch

D

Dual pressure switch

Question 187 1 Marks

Which component is replaced to prevent air entering the refrigerator cabinet?

A

Thermostat

B

Door gasket

C

Door paint

D

Door hinges

Question 188 1 Marks

What is the load resistance in an electrical circuit, if current, I = 2 amp and supply, V = 10 volt?

A

2 Ohms

B

3 Ohms

C

4 Ohms

D

5 Ohms

Question 189 1 Marks

What is the expansion of HVAC?

A

Heavy Vehicle Air Conditioning

B

Heating, Vibration, Auto Correction

C

Heating, Ventilation Automatic Control

D

Heating, Ventilation and Air Conditioning

Question 190 1 Marks

Which extinguishes the fire of flammable liquids?

A

Water

B

Air

C

CO2

D

Oil

Question 191 1 Marks

What is the capacity of doing work?

A

Work

B

Power

C

Force

D

Energy

Question 192 1 Marks

Where to assemble all the controls, microprocessor display board and indicating LED in package AC?

A

DOL

B

Body

C

Panel board

D

Blower compartment

Question 193 1 Marks

What is the capacity of air conditioner if it removes 18000 BTU/hr heat from the space?

A

1.00 T.R

B

1.25 T.R

C

1.50 T.R

D

2.00 T.R

Question 194 1 Marks

Which compressor is used only in central AC systems?

A

Scroll

B

Screw

C

Rotary

D

Centrifugal

Question 195 1 Marks

What is the position of knob selected in thermostat to check its working condition in package AC?

A

Fan only

B

Low cool

C

High cool

D

Medium cool

Question 196 1 Marks

Which parameter of power supply determines the speed of induction motor?

A

Volt

B

Current

C

Volume

D

Frequency

Question 197 1 Marks

What is the colour of oxygen hose pipe in oxy - acetylene welding set?

A

Maroon

B

Green

C

Black

D

Red

Question 198 1 Marks

Which condition is maintained for refrigerant in high side of vapour compression system?

A

Above its critical temperature

B

Below its critical temperature

C

Above its freezing temperature

D

Below its freezing temperature

Question 199 1 Marks

Where the dehydrator is installed in a refrigeration system?

A

Discharge line

B

Capillary line

C

Suction line

D

Liquid line

Question 200 1 Marks

Which refrigerant is highly flammable?

A

HC - Hydro carbon

B

HFC - Hydro fluoro carbon

C

CFC - Chloro fluoro carbon

D

HCFC - Hydro chloro fluoro carbon

Question 201 1 Marks

What is the wet bulb temperature of air if dry bulb temperature is 35 Degree Centigrade and wet bulb depression is 4 Degree Centigrade?

A

30 Degree Centigrade

B

31 Degree Centigrade

C

32 Degree Centigrade

D

33 Degree Centigrade

Question 202 1 Marks

What is the name of joint between pieces located at right angle to each other?

A

T - Joint

B

Lap joint

C

Butt joint

D

Grooved joint

Question 203 1 Marks

What is the reason for poor condensation in split AC?

A

High ambient temperature

B

Low ambient temperature

C

Condenser tube leaky

D

Blower motor failure

Question 204 1 Marks

Where the filter drier is installed in a car AC system?

A

Liquid line

B

Suction line

C

Service line

D

Discharge line

Question 205 1 Marks

Which component is connected in series with defrost heater in a frost free refrigerator?

A

Door switch

B

Cabinet bulb

C

Bimetal thermo

D

Heating element

Question 206 1 Marks

How to change the direction of rotation in
3 Phase induction motor?

A

Change neutral

B

Change all phase

C

Change any two phase

D

Change the winding only

Question 207 1 Marks

Which safety control is actuated by excess of heat /current in package AC?

A

Selector switch

B

Over load relay

C

Water flow switch

D

High pressure cut-out

Question 208 1 Marks

What is the process of accumulation of ice on the surface of evaporator?

A

Frosting

B

Defrosting

C

Evacuating

D

Melting of frost

Question 209 1 Marks

Which bearing is used in condenser motor of outdoor unit in ductable multi split air conditioner?

A

Open ball bearing

B

Thrust bearing

C

Sleeve bearing

D

Ball bearing

Question 210 1 Marks

What is the unit of capacitance?

A

Volt

B

Ampere

C

Farad

D

Coulomb

Question 211 1 Marks

What is the function of magnetic clutch in an automobile air conditioner?

A

Check Rpm of engine shaft

B

Check Rpm of compressor shaft

C

Start and stop the evaporator blower

D

Start and stop the compressor electro magnetically

Question 212 1 Marks

Which method is used to check the leakage of hydro fluoro carbon refrigerants?

A

Electric torch

B

Litmus paper

C

Sulphur candles

D

Electronic leak detector

Question 213 1 Marks

Which evaporator is known as extended surface evaporator?

A

Evaporator tubes

B

Finned evaporator

C

Bare tube evaporator

D

Coiled stake evaporator

Question 214 1 Marks

What are the three pressure actuated electrical control switches connected in series in an automobile air-conditioner?

A

LPC, HPC and Blower-switch

B

Thermostat, Electromagnetic clutch, on-off control

C

Thermostat, Thermostatic expansion valve, Blower-switch

D

Thermostat, Low-pressure control and high pressure control

Question 215 1 Marks

What is the minimum distance to be maintained between the wall and refrigerator condenser?

A

13 cm

B

15 cm

C

18 cm

D

22 cm

Question 216 1 Marks

Which gas is used for pressurising and testing leakage of RAC system?

A

O2

B

N2

C

O3

D

SO2

Question 217 1 Marks

What is the advantage of air washer compared to cooling coil of AHU?

A

Faster heat transfer

B

Quick dehumidification

C

No eliminators are required

D

Can be used in small systems

Question 218 1 Marks

Which refrigerant is used with VRF AC system?

A

R 11

B

R 12

C

R 502

D

R 410A

Question 219 1 Marks

Which type of starter is used for motors in chiller AC plants?

A

Magnetic

B

Hydraulic

C

Pneumatic

D

Electromagnetic

Question 220 1 Marks

Which device controls the air flow in
ducting system?

A

Grille

B

Damper

C

Register

D

Diffuser

Question 221 1 Marks

What is the effect on system performance if the AC system is at undercharged condition?

A

Poor cooling

B

Excess cooling

C

Compressor over loading

D

Compressor trips by HP cut out

Question 222 1 Marks

What is ensured before mounting condenser in car AC?

A

Accessibility for future service

B

Condenser top line to TEV inlet

C

Condenser in line with car radiator

D

Condenser bottom line to discharge line

Question 223 1 Marks

Which part connects the piston with small end of connecting rod in a reciprocating compressor?

A

Piston pin

B

Piston bolt

C

Piston rings

D

Piston sleeve

Question 224 1 Marks

Which gas is used for pressure testing the compressor dome?

A

Air

B

Oxygen

C

Nitrogen

D

Refrigerant

Question 225 1 Marks

Which type of motor drive is used in hermetic compressor in refrigerator?

A

Belt drive

B

Gear drive

C

Direct drive

D

Push drive

Question 226 1 Marks

What is the effect of releasing HFC refrigerants to the atmosphere?

A

Increase global warming potential

B

Increase ozone depleting potential

C

Decrease green house effect

D

Improve water pollution

Question 227 1 Marks

Which file is used for filing wood?

A

Double cut file

B

Single cut file

C

Rasp cut file

D

Smooth file

Question 228 1 Marks

Which is the numerical designation of ammonia refrigerant?

A

700 + ( Molecular mass of NH3) = 717

B

700 + (Molecular mass of NH3) = 718

C

700 + (Molecular mass of NH3) = 719

D

700 + (Molecular mass of NH 3) = 720

Question 229 1 Marks

What is the effect of improper alignment of machines while installing a central AC plant?

A

Silent operation

B

Excess of wear and tear

C

Less noise and vibration

D

Less power consumption

Question 230 1 Marks

What is the physical state of refrigerant at the outlet of condenser in vapour compression cycle?

A

High pressure vapour

B

High pressure liquid

C

Low pressure liquid

D

Low pressure vapour

Question 231 1 Marks

Which process increases the specific humidity of air at constant dry bulb temperature?

A

Humidification of air

B

Sensible cooling of air

C

Sensible heating of air

D

Dehumidification of air

Question 232 1 Marks

Which version of motors are used in ductless multisplit system?

A

Bioptional drive

B

Trioptional drive

C

Variable frequency drive

D

Constant frequency drive

Question 233 1 Marks

Which valve helps to attend mechanical faults without wasting the gas in split AC?

A

Gate valve

B

Float valve

C

Service valve

D

Expansion valve

Question 234 1 Marks

How does the evaporator frost affect the sub zero temperature thermally in refrigerator?

A

As conductor

B

As insulator

C

As convector

D

As radiator

Question 235 1 Marks

Which tool is used for skinning the insulation of cables and cleaning the wire surface?

A

Hacksaw

B

Firmer chisel

C

Electrician's knife

D

Combination pliers

Question 236 1 Marks

What is the method of flushing the indoor coils?

A

Using nitrogen

B

Pressurised air

C

Chemical cleaning

D

Mechanical cleaning

Question 237 1 Marks

What is the cylinder colour code of R 22 refrigerant?

A

White

B

Green

C

Orchid

D

Orange

Question 238 1 Marks

Which electrical control cuts off heating element in frost free refrigerator?

A

Bimetal thermo

B

Thermostat

C

Relay

D

Timer

Question 239 1 Marks

What is the reason for the compressor motor burn out in a window air conditioner?

A

Defective fan capacitor

B

Defective fan motor

C

Defective blower

D

Defective OLP

Question 240 1 Marks

Which components are used in AHU of central AC plant?

A

Blower, Air filter, Evaporator

B

Condenser, Fan, Compressor

C

Evaporator, Compressor, Blower

D

Air filter, Compressor, Condenser

Question 241 1 Marks

Why the supply air throw is decreased in window AC?

A

Normal RPM of fan motor

B

Clean air filter

C

Refrigerant leaks

D

Frost blocks air circulation

Question 242 1 Marks

What is the minimum cross sectional area of the ducts used with bus AC?

A

400 cm2

B

500 cm2

C

600 cm2

D

700 cm2

Question 243 1 Marks

What is the function of refrigerant fluid in a refrigerator?

A

Releases heat inside the cabinet

B

Absorbs heat from inside the cabinet

C

Absorbs heat from outside the cabinet

D

Absorbs heat from bottom side cabinet

Question 244 1 Marks

Which type of diode is used for communication circuits?

A

Signal diode

B

Zener diode

C

Rectifier diode

D

Switching diode

Question 245 1 Marks

What is the reason for air conditioner running continuously but no cooling effect ?

A

Condensation poor

B

Refrigerant is more

C

Refrigerant leaked

D

Over charged oil

Question 246 1 Marks

What is ensured before removing a leaky evaporator in a refrigerator?

A

Recharge refrigerant to the system

B

Check the drain tray of evaporator

C

Removal of the thermostat sensor

D

Pressurize the system with refrigerant

Question 247 1 Marks

What is the purpose of using the water cooled condenser in industrial AC plant?

A

Reduce the pressure

B

Increase the temperature

C

Reject more heat to water

D

Absorb less heat from system

Question 248 1 Marks

Which fan motor speed is used with outdoor unit in split AC?

A

Single speed

B

Double speed

C

Triple speed

D

Five speed

Question 249 1 Marks

What is the cause of oil foaming in compressor crankcase at the time of starting?

A

Poor condensation

B

Damaged oil separator

C

Excess oil in crankcase

D

Defective oil heater/circuit

Question 250 1 Marks

Which cooling medium is used to condense the refrigerant vapour in plate and tube condenser?

A

Natural Air

B

Forced Air

C

Water

D

Brine solution

Question 251 1 Marks

What is the percentage of HCl used for making descaling solution with water?

A

0.01

B

0.05

C

0.15

D

0.55

Question 252 1 Marks

Which part of car AC compressor actuates the piston directly?

A

Crank shaft and connecting rod

B

Rotor and stator

C

Swash plate

D

Blower unit

Question 253 1 Marks

How the zeotropic refrigerant is taken from the cylinder for charging it into RAC system?

A

Liquid state

B

Vapour state

C

Vapour and liquid

D

Super heated vapour

Question 254 1 Marks

What are the multi speed of blower motor used in indoor unit of ductable split air conditioner?

A

ow - 500 rpm, medium - 550rpm, high - 720 rpm

B

Low - 800 rpm, medium - 850rpm, high - 920 rpm

C

Low - 900 rpm, medium - 950rpm, high - 1100 rpm

D

Low -1000 rpm, medium -1200rpm, high -1350 rpm

Question 255 1 Marks

Where the air temperature is measured to check the performance of package AC?

A

Supply grille

B

Blower inlet

C

Atmosphere

D

Condenser outlet

Question 256 1 Marks

What tonnage capacity of split AC unit uses 150/200 MFD starting capacitor?

A

1 TR

B

1.5 TR

C

2.0 TR

D

2.5 TR

Question 257 1 Marks

Which refrigerant control is used in car AC?

A

Hand shut off valve

B

Automatic expansion valve

C

Thermostatic expansion valve

D

Thermal electric expansion valve

Question 258 1 Marks

What is the capacity of compressor motor used in 1Ton window air conditioner?

A

0.50 HP

B

0.75 HP

C

0.95 HP

D

1.00 HP

Question 259 1 Marks

What is the unit of inductance?

A

Ohm

B

Henry

C

Farad

D

Ampere

Question 260 1 Marks

What is the revolving part of induction motor?

A

Stator

B

Rotor

C

Relay

D

Winding

Question 261 1 Marks

What is the tool used to remove the slag from the welding?

A

Tongs

B

Chipping hammer

C

Cross peen hammer

D

Ball peen hammer

Question 262 1 Marks

What is the test pressure of cooling coils during manufacture?

A

150 psig

B

250 psig

C

350 psig

D

450 psig

Question 263 1 Marks

What is the reason for Very high condenser temperature in a window air conditioner?

A

Water splashes condenser

B

More air flows into the condenser

C

Fan motor working in good condition

D

Dust accumulated in the condenser fins

Question 264 1 Marks

What is the purpose of cooling tower in central AC plant?

A

Cool the chilled water

B

Maintain refrigerant flow

C

Cool the liquid refrigerant

D

Cool the condenser water

Question 265 1 Marks

Which method prevents the foul smell of drainage entering the AHU?

A

Strainer

B

U - trap

C

Louvers

D

Exhaust fan

Question 266 1 Marks

Which winding of compressor motor is directly connected across voltage relay coil?

A

Main winding

B

Starting winding

C

Running winding

D

Auxiliary winding

Question 267 1 Marks

What is the energy of a body by virtue of its position?

A

Wind energy

B

Kinetic energy

C

Potential energy

D

Electrical energy

Question 268 1 Marks

What is low side pressure range in HFC134a car AC at an ambient range of 32 Degree Centigrade to 35 Degree Centigrade?

A

1 kg/cm2 - 3 kg/cm2

B

2 kg/cm2 - 4 kg/cm2

C

3 kg/cm2 - 5 kg/cm2

D

4 kg/cm2 - 6 kg/cm2

Question 269 1 Marks

What is the unit of electric current?

A

Ampere

B

Farad

C

Ohm

D

Volt

Question 270 1 Marks

Which refrigerant is used in vapour compression cycle?

A

Secondary refrigerant

B

Primary refrigerant

C

Brine solution

D

Water

Question 271 1 Marks

What is the effect of sludge in car AC?

A

Chokes the orifice of TEV

B

Blocks the orifice of AEV

C

Closes the orifice of TEEV

D

Closes the orifice of capillary

Question 272 1 Marks

What is the unit of electrical energy?

A

Volt

B

Watt

C

Ampere

D

Kilo watt hour

Question 273 1 Marks

Which is the mounting location of evaporator in ductable split unit?

A

Floor mounting

B

Wall mounting

C

Ceiling mounting

D

Roof mounting

Question 274 1 Marks

What is the advantage of universal colour coding of refrigerant cylinders?

A

Easy to identify

B

Make good appearance

C

Prevent corrosion on cylinder

D

Provide extra strength to cylinder

Question 275 1 Marks

What is the effect of partially choked thermostatic expansion valve in central AC plant?

A

Iced condenser

B

Frosted evaporator

C

Hot expansion valve

D

Frosted expansion valve

Question 276 1 Marks

Which is the point angle of a twist drill used for zinc alloy?

A

90 Degree

B

100 Degree

C

118 Degree

D

125 Degree

Question 277 1 Marks

1 Which control device is used to maintain the room air temperature?

A

OLP

B

Relay

C

Thermostat

D

Selector switch

Question 278 1 Marks

Which type of load consumes more energy in an AC plant system?

A

Air ventilation

B

Air distribution

C

Water circulation

D

Heating and cooling

Question 279 1 Marks

Which winding has more inductance in refrigerator compressor motor?

A

Run

B

Start

C

Common

D

Start and common

Question 280 1 Marks

What are the controls connected in series with the magnetic clutch of compressor in car AC?

A

Thermostat, LPC, HPC

B

LPC, Blower Fan Motor

C

HPC, Condenser Fan Motor

D

Thermostat, Condenser Fan Motor

Question 281 1 Marks

Which component belongs to indoor unit of split AC?

A

Compressor

B

Condenser

C

Evaporator

D

Drier

Question 282 1 Marks

What is the absolute pressure of gas cylinder if the gauge reads 15.3 p.s.i.g?

A

10 p.s.i.a

B

20 p.s.i.a

C

30 p.s.i.a

D

40 p.s.i.a

Question 283 1 Marks

How to position the liquid line valve to start the pump down operation in split AC?

A

Closed

B

Opened

C

Back seated

D

Back seat crack

Question 284 1 Marks

What is the diameter of liquid line used with 5 TR if the suction line is 7/8 OD by up flow?

A

1/2? OD

B

5/16 ? OD

C

3/8 ? OD

D

3/4 ?OD

Question 285 1 Marks

Which components maintain the pressure difference in RAC system?

A

Condenser and filter

B

Evaporator and motor

C

Receiver and condenser

D

Compressor and expansion device

Question 286 1 Marks

Which is the effective method for refrigerant recovery?

A

Condensing unit

B

Charge migration

C

Push pull recovery

D

Use of system's compressor

Question 287 1 Marks

Which thickness of PUF has the least thermal conductivity?

A

One inch

B

Two inch

C

Four inch

D

Three inch

Question 288 1 Marks

What are the passive components used in
electronic circuits?

A

Resistors, capacitors and inductors

B

Transformers and semiconductors

C

Semi conductors and transistors

D

Transistors, diodes and SCRs

Question 289 1 Marks

Which refrigeration system works on
directly by the heat energy?

A

Jet refrigeration

B

Mechanical refrigeration

C

Vapour absorption refrigeration

D

Vapour compression refrigeration

Question 290 1 Marks

Which component is used as a switching device in electronic circuit?

A

SCR

B

Diode

C

Capacitor

D

Zener diode

Question 291 1 Marks

How to prevent the small pieces of glass wool affecting the eyes?

A

Wearing goggles

B

Wearing gloves

C

Using mask

D

Using shoes

Question 292 1 Marks

Which device controls the moisture in AC room air?

A

Humidistat

B

Hydrometer

C

Hygrometer

D

Anemometer

Question 293 1 Marks

How much minimum gap is left on either side of the refrigerator from the wall during installation?

A

5 cm

B

10 cm

C

15 cm

D

25 cm

Question 294 1 Marks

Which level of vacuum is required before charging HFC 134a in car AC?

A

500 micron

B

400 micron

C

300 micron

D

200 micron

Question 295 1 Marks

What is the working condition of component during defrost cycle in frost free refrigerator?

A

Evaporator fan motor is running

B

Compressor is not running

C

Thermostat cuts off

D

Relay activated

Question 296 1 Marks

Which device is used to measure the static and total pressure of air in ducting systems?

A

Pitot tube

B

Gauge manifold

C

Pressure gauge

D

Compound gauge

Question 297 1 Marks

How to neutralise the concentration of leaked ammonia from air

A

Recover ammonia from air

B

Spraying a lot of water

C

Shut down the plant

D

Spray Hydrochloric acid

Question 298 1 Marks

How much is the maximum capacity of refrigerant to be filled in a returnable service cylinder?

A

Up to 95%

B

Up to 90%

C

Up to 85%

D

Up to 80%

Question 299 1 Marks

Which is used to clean the condenser fins of a refrigerator?

A

Painting brush

B

Diluted acid

C

Soap solution

D

Fin comb

Question 300 1 Marks

Which horizontal distance is preferred between indoor and outdoor units in ductable split AC installation?

A

15 meters

B

12 meters

C

20 meters

D

25 meters

Question 301 1 Marks

What is the purpose of using humidistat in an industrial AC plant?

A

Purifies air

B

Add moisture to air

C

Control humidity of air

D

Remove moisture from air

Question 302 1 Marks

Which gas is universally taken as the basic reference for GWP?

A

SO2

B

CO2

C

NH3

D

AIR

Question 303 1 Marks

What is phenotherm?

A

A ducting clamp

B

An insulation material

C

A chemical substance

D

Temperature measuring device

Question 304 1 Marks

What is the equivalent of 1 mm of Hg in
terms of microns?

A

500

B

1000

C

1500

D

2000

Question 305 1 Marks

Which part of the working refrigeration system, the non condensable accumulate?

A

Accumulator

B

Top of condenser

C

Evaporator outlet

D

Compressor crankcase

Question 306 1 Marks

Why the filler metal does not melt and flow into the joint in bronze welding of copper?

A

Excess use of flux

B

Due to excess of polished surface

C

Surface coated with oxides or oily material

D

Excessive heating of metal s surface

Question 307 1 Marks

Why the water flow switch is bypassed to test the HP control switch in package AC?

A

Make the unit not to trip

B

Raise the oil pressure more

C

Stopping the unit immediately

D

Lower the head pressure in compressor

Question 308 1 Marks

Why the service port fitting size differs in HFC-134a from CFC-12 car AC system?

A

Increases quantity of refrigerant charge

B

Decreases quantity of refrigerant charge

C

Avoids cross contamination of refrigerants

D

Improves performance of car air conditioners

Question 309 1 Marks

How the total heat of air is represented in psychrometric chart?

A

Entropy

B

Enthalpy

C

Latent heat

D

Sensible heat

Question 310 1 Marks

Which stabilizer capacity is used for 1 Ton window air conditioner?

A

2 KVA

B

3 KVA

C

4 KVA

D

5 KVA

Question 311 1 Marks

Which gas is produced by the chemical reaction of carbide and water?

A

Oxygen

B

Nitrogen

C

Acetylene

D

Carbon dioxide

Question 312 1 Marks

Which expansion valve is suitable for constant load operation?

A

King valve

B

Relief valve

C

Low side float valve

D

Automatic expansion valve

Question 313 1 Marks

What is ensured before starting a vacuum pump?

A

Correct oil level

B

Capacity of the pump

C

Weight of vacuum pump

D

Available ac power supply

Question 314 1 Marks

What is done after gas charging and pinching the process tube in refrigerator?

A

Flaring

B

Charging

C

Swaging

D

Brazing

Question 315 1 Marks

Which types of heat are involved in ventilation and infiltration of air to AC space?

A

Sensible heat and solar heat

B

Sensible heat and latent heat

C

Radiant heat and specific heat

D

Latent heat of water-vapour only

Question 316 1 Marks

What is the formula to find out the
synchronous speed of induction motor?

A

Ns=(150P/f)

B

Ns=(120f/P)

C

Ns=(150f/P)

D

Ns=(120P/f)

Question 317 1 Marks

Which valve is used to release the non condensable gases from AC plant?

A

Purge valve

B

Check valve

C

Service valve

D

Solenoid valve

Question 318 1 Marks

Which capacity of fan motor is used in 1Ton window air conditioner?

A

1/5 HP

B

1/10 HP

C

1/16 HP

D

1/20 HP

Question 319 1 Marks

How electrons flow in a battery circuit?

A

Phase to earth

B

Phase to neutral

C

Positive to negative polarity

D

Negative polarity to positive polarity

Question 320 1 Marks

What type of compressor motor is used in inverter split AC?

A

Constant speed compressor motor

B

Centrifugal compressor motor

C

Open type compressor motor

D

Variable speed motor

Question 321 1 Marks

Which is the mounting location of evaporator in ductable split unit?

A

Floor mounting

B

Wall mounting

C

Ceiling mounting

D

Roof mounting

Question 322 1 Marks

Which is the source of drive for compressor shaft in car AC?

A

Magnetic clutch

B

Condenser fan

C

Engine shaft

D

Blower fan

Question 323 1 Marks

Which component belongs to outdoor unit of split AC?

A

Blower

B

Air filter

C

Compressor

D

Evaporator coil

Question 324 1 Marks

Where the filter drier is installed in window AC refrigerant circuit?

A

Discharge line

B

Suction line

C

Service line

D

Liquid line

Question 325 1 Marks

How many terminals are there in a Silicon Controlled Rectifier (SCR)?

A

One

B

Two

C

Four

D

Three

Question 326 1 Marks

Why HCFC 22 refrigerant is recycled?

A

Decrease the cost of production

B

Make use of the same lubricant

C

Reduce ODP and GWP of environment

D

Increase the efficiency of RAC systems

Question 327 1 Marks

What is the advantage of recycling R 134a refrigerant?

A

Minimise air pollution

B

Reduce global warming

C

Increase water pollution

D

Increase ozone depletion

Question 328 1 Marks

Which winding has low resistance in resistance start induction run motor?

A

Running winding

B

Starting winding

C

Auxiliary winding

D

Common winding

Question 329 1 Marks

Which type of conductor is used for bus bars?

A

Solid conductor

B

Thermal conductor

C

Stranded conductor

D

Standard conductor

Question 330 1 Marks

Which instrument indicates the correct floor level to install package unit?

A

Sprit level

B

Tee square

C

Screw gauge

D

Vernier caliper

Question 331 1 Marks

Which component is turned off while defrost heater is energised?

A

Cabinet bulb

B

Evaporator fan

C

Thermostat sensor

D

Over load protector

Question 332 1 Marks

Which type of expansion device is used in frost free refrigerator?

A

Float valve

B

Capillary tube

C

Automatic expansion valve

D

Thermostatic expansion valve

Question 333 1 Marks

How the space between the false ceiling and the building main ceiling is used in handling of air in central AC plant?

A

Exhaust duct

B

Fresh air duct

C

Return air duct

D

Supply air duct

Question 334 1 Marks

What is the percentage range of silver in copper to copper pipes brazing rod?

A

20 to 35%

B

35 to 45%

C

45 to 60%

D

60 to 100%

Question 335 1 Marks

What is the process involved for converting AC to DC power supply?

A

Inversion

B

Regulation

C

Convection

D

Rectification

Question 336 1 Marks

Which valve is kept closed to check the function of low pressure switch?

A

Reed valve

B

Suction valve

C

Liquid line valve

D

Discharge service valve

Question 337 1 Marks

Which temperature is measured first in sling psychrometer after whirling?

A

Dry bulb temperature of air

B

Wet bulb temperature of air

C

Absolute temperature of air

D

Accurate temperature of air

Question 338 1 Marks

Which is sensed by TEV in response to heat load variation?

A

Sub cool in liquid line

B

Discharge temperature

C

Super heat in suction line

D

Evaporating temperature

Question 339 1 Marks

What is the result if discharge reed is broken in open type compressor?

A

Poor pumping

B

More pumping

C

Oil pumping

D

No pumping

Question 340 1 Marks

What is the effect of bimetal thermo stucks in ON position in frost free refrigerator?

A

Accumulation of frost

B

More cooling

C

Poor cooling

D

No cooling

Question 341 1 Marks

Which types of heat are considered for occupants heat gain in AC space?

A

Radiant and latent heat

B

Sensible and latent heat

C

Sensible and radiant heat

D

Specific and sensible heat

Question 342 1 Marks

Why the capillary tube is preferred as an
expansion device?

A

No system pressure equalising

B

Inexpensive and has no moving parts

C

Expensive and more moving parts

D

Periodical servicing is required

Question 343 1 Marks

What is the supply voltage if a current of 2 ampere flows through 10 Ohm resistor in a circuit?

A

20 Volt

B

45 Volt

C

55 Volt

D

65 Volt

Question 344 1 Marks

Which design data is used for indoor air in summer air conditioning?

A

20 DegreeC +/- 1 DegreeC and 30% RH

B

22 DegreeC +/- 1 DegreeC and 40% RH

C

24 DegreeC +/- 1 DegreeC and 50% RH

D

24 DegreeC +/- 1 DegreeC and 50% RH

Question 345 1 Marks

Which device is used to exhaust the room air in window AC?

A

Damper

B

Air filter

C

Filter drier

D

Air washer

Question 346 1 Marks

Which electronic component is the voltage regulator?

A

Zener diode

B

Transistor

C

Triac

D

Diac

Question 347 1 Marks

Which component removes the burrs and moisture from the circulating refrigerant in AC plant?

A

Air filter

B

Filter drier

C

HEPA filter

D

Oil strainer

Question 348 1 Marks

Which type of processor control is used for safety in package air conditioner?

A

Electric

B

Mechanic

C

Electronic

D

Pneumatic

Question 349 1 Marks

Which is connected in series with start capacior in motor circuit?

A

Starting winding

B

Common terminal

C

Running Terminal

D

Running winding

Question 350 1 Marks

Which thermistor s resistance increases if the temperature is decreased?

A

PTC

B

NTC

C

VDR

D

LDR

Question 351 1 Marks

What is the reason for excessive frost on evaporator coil in window AC?

A

Evaporator fins not blocked by dust

B

Blower rotating at higher speed

C

Air filter blocked completely

D

More air circulation in evaporator

Question 352 1 Marks

What is the material composition of a Tin man s solder?

A

50% Tin 50% Zinc

B

50% Tin 50% lead

C

50% Zinc 50% lead

D

50% Tin 50% Bronze

Question 353 1 Marks

Which type of evaporator is used in house hold refrigerator?

A

Plate evaporator

B

Tube in tube evaporator

C

Shell and coil evaporator

D

Shell and tube evaporator

Question 354 1 Marks

Which material is used to make ducts in split AC?

A

Thermocole

B

GI sheet

C

Wood

D

Fibre

Question 355 1 Marks

What is the preventive maintenance schedule of blower motor s speed and end play in package AC?

A

Daily

B

Yearly

C

Weekly

D

Monthly

Question 356 1 Marks

What is the velocity pressure of air in a duct if the total pressure and static pressure are known?

A

Sum of static and total pressures

B

Sum of dynamic and total pressures

C

Difference in static and total pressures

D

Difference in dynamic and total pressures

Question 357 1 Marks

Why frost accumulates in window AC evaporator?

A

Over charge of refrigerant

B

Less charge of refrigerant

C

Capillary chocking

D

Air filter blocked

Question 358 1 Marks

Where does the ozone layer exist in atmosphere?

A

Mesosphere

B

Stratosphere

C

Ionosphere

D

Exosphere

Question 359 1 Marks

How the potential relay coil is connected internally to the relay terminals?

A

5 and 1

B

5 and 4

C

5 and 2

D

2 and 4

Question 360 1 Marks

Why the capacitor is tested inside a box or case?

A

Explodes safely

B

Erodes the test kit

C

Corrodes the test kit

D

Releases poisonous gas

Question 361 1 Marks

What is the differential of control switch if it cuts in at 29 kg/cm2 and cuts out at 34 kg/cm2?

A

5 kg / cm2

B

10 kg / cm2

C

15 kg / cm2

D

20 kg / cm2

Question 362 1 Marks

Which fan motor speed is used with outdoor unit in split AC?

A

Single speed

B

Double speed

C

Triple speed

D

Five speed

Question 363 1 Marks

Which type of heat is considered for tube light s heat gain in AC space?

A

Latent heat

B

Conduction heat

C

Specific heat

D

Sensible heat

Question 364 1 Marks

What is the reason for Compressor does not start ?

A

Defective fresh air damper

B

Defective oscillation motor

C

Defective fan motor

D

Defective OLP

Question 365 1 Marks

Which electronic component senses the temperature in indoor unit of VRV system?

A

Resistor

B

Thyristor

C

Transistor

D

Thermistor

Question 366 1 Marks

Which factor determines the current setting during welding?

A

Types of joint

B

Position of weld

C

Length of electrode

D

Diameter of electrode

Question 367 1 Marks

How many speed selection is used with indoor air blower in ductable multi split AC?

A

One - speed

B

Two - speed

C

Three - speed

D

Four - speed

Question 368 1 Marks

What is the benefit of VRV system?

A

Bigger in size

B

Many controls

C

Energy saving

D

Saving refrigerant

Question 369 1 Marks

What is the unit of capacitance used with single phase induction motors in domestic RAC system?

A

Kilo ohm

B

Microfarad

C

Milli henry

D

Milli ampere

Question 370 1 Marks

Which valve is used in capacity control system employing hot gas bypass?

A

Relief valve

B

Safety valve

C

Solenoid valve

D

Reversing valve

Question 371 1 Marks

How the indoor unit acts during heating cycle of heat pump?

A

Condenser

B

Evaporator

C

Expansion device

D

Electrical heater

Question 372 1 Marks

Which is the minimum vaccum level
preferred in microns before gas charging a system?

A

2000

B

1750

C

750

D

500

Question 373 1 Marks

What is the cause of bubbles in liquid line at sight glass in car AC system?

A

No refrigerant charge

B

Shortage of refrigerant

C

Over charge of refrigerant

D

Correct charge of refrigerant

Question 374 1 Marks

Why the AHU outlet is connected to supply duct with canvas material?

A

Quick replacement

B

Low installation cost

C

Low maintenance cost

D

Avoid vibration of air transmission

Question 375 1 Marks

Which fan is used in condensing unit of ductable split air conditioner?

A

Forward curved fan

B

Centrifugal fan

C

Propeller fan

D

Radial fan

Question 376 1 Marks

What is the physical state of ammonia at condenser inlet in vapour absorption system?

A

Solid

B

Liquid

C

Vapour

D

Semi solid

Question 377 1 Marks

What is the maximum TR capacity operated with Single phase AC supply?

A

1.00 TR

B

1.5 TR

C

2.0 TR

D

5 TR

Question 378 1 Marks

Why there is no frosting at the bottom only in plate coil evaporator used with refrigerator?

A

Shortage of refrigerant

B

Oil present in the coil

C

Excess of refrigerant

D

Liquid in the coil

Question 379 1 Marks

Which is increased by the fins of condenser tubes in window air conditioner?

A

Heat transfer rate

B

Power consumption

C

Discharge pressure

D

Refrigerant flow rate

Question 380 1 Marks

How many parameters are needed to locate all properties of moist air in psychrometric chart?

A

One

B

Two

C

Four

D

Three

Question 381 1 Marks

What is the value of starting capacitor used for 1.5TR capacity window air conditioner?

A

40 to 60 MFD

B

80 to 100 MFD

C

130 to 150 MFD

D

150 to 160 MFD

Question 382 1 Marks

Which tool is used for service valve
operations in package AC?

A

Cutting pliers

B

Screw spanner

C

Ratchet key/wrench

D

Double end spanner

Question 383 1 Marks

Which material is used to make the evaporator of refrigerator?

A

Galvanised iron

B

Stainless steel

C

Aluminium

D

Brass

Question 384 1 Marks

What is the barometer reading at sea level in Hg column?

A

760 mm

B

750 mm

C

740 mm

D

730 mm

Question 385 1 Marks

Which is the common terminal while Ohm meter reads AB = 10 Ohm, AC = 15 Ohm and BC = 25 Ohm if the motor terminals are A, B and C?

A

Terminal A

B

Terminal B

C

Terminal C

D

Earth Terminal

Question 386 1 Marks

Which differentiates the industrial AC compared to domestic AC system?

A

Blowers are used

B

Separate plant room

C

Condensation of refrigerants

D

Filters for air and refrigerants

Question 387 1 Marks

How the cylinders of gas welding set are secured in trolley?

A

By cable

B

Using chain

C

Tightened with rope

D

Tied up with belt

Question 388 1 Marks

What is the reason for no cooling effect in car AC?

A

Air in the system

B

Excess of refrigerant

C

Refrigerant leaked

D

Moisture in the system

Question 389 1 Marks

What is the cause of reduced supply air throw though air filter is clean in window AC?

A

No frost in the evaporator

B

Frost accumulated in the evaporator

C

Dust accumulated in the condenser

D

No dust accumulated in the evaporator

Question 390 1 Marks

Which material is used for making zener diode?

A

Lead

B

Silicon

C

Titanium

D

Platinum

Question 391 1 Marks

Which cooling medium is used to cool the motor of a hermetic reciprocating compressor in AC?

A

Discharge vapour

B

Liquid refrigerant

C

Suction vapour

D

Water

Question 392 1 Marks

Which type of fan motor is used in window air conditioner?

A

Three phase single shaft motor

B

Single phase single shaft motor

C

Three phase double end shaft motor

D

Single phase double end shaft motor

Question 393 1 Marks

What is the category of R 290 refrigerant?

A

Halocarbons

B

Azeotropes

C

Hydrocarbons

D

Organic compounds

Question 394 1 Marks

Which motor has the least starting
torque?

A

CSIR

B

CSR

C

RSIR

D

PSC

Question 395 1 Marks

Which type of compressor is used for domestic refrigerator?

A

Semi sealed compressor

B

Centrifugal compressor

C

Hermetic compressor

D

Open type compressor

Question 396 1 Marks

Which relay is used in capacitor start, capacitor run (CSR) compressor motor?

A

Voltage relay

B

Current relay

C

Thermal relay

D

Amperage relay

Question 397 1 Marks

How the pH of water is checked for acidic or alkaline?

A

By hydro meter

B

By hygro meter

C

Using litmus paper

D

Pressure relief valve

Question 398 1 Marks

Which refrigerant is used in domestic refrigerator?

A

R 22

B

R 32

C

R 134 a

D

R 407 c

Question 399 1 Marks

What is measured by clamp tester during 'Test run' of package AC?

A

Idle pressure

B

Running current

C

Rotation per minute

D

Vacuum holding strength

Question 400 1 Marks

Which valve is opened first after installing the package AC for test run?

A

Ball valve

B

Globe valve

C

Service valve

D

Solenoid valve

Question 401 1 Marks

What is the remedy for the defective OLP in a window air conditioner?

A

Repair the OLP

B

Replace the OLP

C

Remove the parts

D

Repair the heater element

Question 402 1 Marks

Which device maintains a constant DC output?

A

Load regulators

B

Rectifier circuits

C

Current limiters

D

Voltage regulators

Question 403 1 Marks

What is measured by Anemometer?

A

Velocity of air

B

Direction of air-flow

C

Total pressure of air

D

Static pressure of air

Question 404 1 Marks

What is the cause of reduction in fan's air flow?

A

Leak in the system

B

Fan capacitor is weak

C

Refrigerant under charge

D

Supply voltage is normal

Question 405 1 Marks

What type of material is used to support the tubes on both sides of air cooled condenser?

A

Copper sheets

B

Mild steel sheet

C

Aluminium sheets

D

Galvanised iron sheets

Question 406 1 Marks

Which instrument measures the humidity of air?

A

Barometer

B

Manometer

C

Hygrometer

D

Hydrometer

Question 407 1 Marks

Which part of water pump becomes worn out fast?

A

Bearing

B

Impeller

C

Water seal

D

Shaft sleeve

Question 408 1 Marks

Which extinguishes the fire on electrical equipment?

A

Oil

B

Foam

C

Water

D

Halon

Question 409 1 Marks

What is the boiling point of pure water in centigrade scale?

A

212 Degree Centigrade

B

100 Degree Centigrade

C

32 Degree Centigrade

D

0 Degree Centigrade

Question 410 1 Marks

Which process decreases the dry bulb temperature of air at constant specific humidity?

A

Humidification of air

B

Sensible cooling of air

C

Sensible heating of air

D

Dehumidification of air

Question 411 1 Marks

Which compressor dome handles high pressure and high temperature vapour?

A

Semi hermetic reciprocating compressor

B

Open type reciprocating compressor

C

Hermetic reciprocating compressor

D

Hermetic rotary compressor

Question 412 1 Marks

What is the effect of contamination in refrigeration system?

A

High heating

B

Poor cooling

C

Low pressure

D

Low humidity

Question 413 1 Marks

What is the cause for refrigerator door gap at closing position?

A

Uneven floor level

B

Either side gap more

C

Either side gap less

D

Uneven condenser level

Question 414 1 Marks

Which meter indicates the true power directly in an electrical circuit?

A

Ammeter

B

Ohm meter

C

Watt meter

D

Volt meter

Question 415 1 Marks

What is the temperature set in thermostat that stops the compressor motor?

A

Cut in

B

Range

C

Cut out

D

Differential

Question 416 1 Marks

Which part of tube cutter is used for removing the burrs from copper tubes?

A

Roller

B

Cutter

C

Reamer

D

Bender

Question 417 1 Marks

What is the benefit of preventive maintenance in AC plant?

A

Reduce water flow

B

Increase running cost

C

Prevent plant s break down

D

Decrease refrigerant charge

Question 418 1 Marks

How much cut out point is set in high pressure control in package AC using R-22?

A

12 kg/cm2

B

15 kg/cm2

C

17 kg/cm2

D

20 kg/cm2

Question 419 1 Marks

Which refrigerant is inactive to ozone layer?

A

R 12

B

R 13

C

R 22

D

R 134a

Question 420 1 Marks

Which part of the compressor converts rotary into reciprocating motion of piston in car AC?

A

Connecting rod

B

Magnetic clutch

C

Swash plate

D

Crank shaft

Question 421 1 Marks

Which component protects the electrical circuit and loads from excess current?

A

Fuse

B

Relay

C

Relief valve

D

Transformer

Question 422 1 Marks

What is the effect of releasing HCFC refrigerants to atmosphere?

A

Increases ODP and GWP

B

Decreases GWP and ODP

C

Decreases TEWI

D

Inactive to TEWI

Question 423 1 Marks

What is the desiccant used in dehydrator of hydrocarbon charged RAC unit?

A

Silica gel

B

Ammonia

C

Sulphur dioxide

D

Calcium chloride

Question 424 1 Marks

What is the purpose of using goggles during chipping the slag from weld bead?

A

To protect eyes

B

To protect hand

C

To protect leg

D

To protect head

Question 425 1 Marks

What is the reason for low discharge line temperature in chiller AC?

A

Excess refrigerant

B

High evaporator load

C

Insufficient refrigerant

D

Condenser water pump not working

Question 426 1 Marks

Which method of welding process is suitable to nonferrous dissimilar metals?

A

Cold welding

B

Explosion welding

C

Brazing and bronze welding

D

Ultrasonic method of welding

Question 427 1 Marks

Which instrument is used for measuring
heat?

A

Thermometer

B

Anemometer

C

Calorimeter

D

Ammeter

Question 428 1 Marks

What is the equivalent of one microfarad in farad?

A

10-3 farad

B

10-6 farad

C

10-9 farad

D

10-12 farad

Question 429 1 Marks

What is the advantage of ductable air conditioner over window air conditioner?

A

Higher cost

B

Noisy operation

C

Silent operation

D

Needs more space

Question 430 1 Marks

Why the top of dome is hot in a scroll compressor?

A

Discharge plenum is at top

B

Suction super heat is less

C

Suction gas not cooled

D

Undercharged system

Question 431 1 Marks

Which parameter is checked if the air flow in supply duct is reduced in central AC plant?

A

Condenser temperature

B

Cooling water temperature

C

Blower motor ampere/speed

D

Compressor discharge temperature

Question 432 1 Marks

Why the U trap is provided in water drain line of AHU?

A

Allows air from outside

B

Block dust from outside

C

Prevent entry of foul smell

D

Ensure free flow of drain water

Question 433 1 Marks

Which parameter of heater element is increased in OLP due to hot compressor dome?

A

Voltage

B

Resistance

C

Capacitance

D

Magnetic field

Question 434 1 Marks

Which process absorbs heat from the cabinet in refrigerator?

A

Expansion

B

Compression

C

Evaporation

D

Condensation

Question 435 1 Marks

What is the cut out temperature of bimetal thermo in frost free refrigerator?

A

5 Degree Centigrade

B

10 Degree Centigrade

C

20 Degree Centigrade

D

25 Degree Centigrade

Question 436 1 Marks

What is the remedy for scaled up water tubes of water cooled condenser?

A

Clean the surface

B

Wipe the condenser fins

C

Descale the condenser tubes

D

Wash the condenser with soap water

Question 437 1 Marks

What is the effect of sensing higher
temperature by thermistor NTC?

A

Resistance increases

B

Resistance decreases

C

Resistance becomes zero

D

Resistance becomes infinity

Question 438 1 Marks

What is the reason for water dripping inside the AC bus?

A

Drain pan is leak proof

B

Leakage of evaporator coil

C

Poor insulation at the bottom of drain pan

D

Worn out shock absorbers on the bus wheels

Question 439 1 Marks

How many diodes are required for making a
bridge rectifier circuit?

A

One

B

Two

C

Four

D

Three

Question 440 1 Marks

Why the stainless-steel metal is used to make evaporator in ice plant?

A

Erosive

B

Galvanic

C

Reactive

D

Non corrosive

Question 441 1 Marks

Where the sensor bulb of Thermostatic Expansion Valve is clamped?

A

Liquid Line

B

Suction Line

C

Discharge Line

D

Inside the compressor

Question 442 1 Marks

Which is a positive displacement
compressor?

A

Centrifugal compressor

B

Scroll compressor

C

Water pump

D

Oil pump

Question 443 1 Marks

What is the reason for sweating of water on drier filter?

A

Air filter blocked

B

Partially chocked drier filter

C

More air flows through the evaporator

D

Dust accumulated on condenser

Question 444 1 Marks

Which material is used to make electrode holder for welding?

A

Steel

B

Cast iron

C

Cast iron

D

Copper alloy

Question 445 1 Marks

What is the advantage of sealed system compared to open type system?

A

Mechanical efficiency is greater

B

Cylinder lubrication is easier

C

Any refrigerant can be used

D

No shaft seal is required

Question 446 1 Marks

Which material is used to make ducts in split AC?

A

Thermocole

B

GI sheet

C

Wood

D

Fibre

Question 447 1 Marks

Which valve is closed during compression stroke in reciprocating compressor?

A

Service valve

B

Liquid line valve

C

Discharge valve

D

Suction valve

Question 448 1 Marks

Which component absorbs the maximum heat from the cabinet materials in frost free refrigerator?

A

Condenser

B

Evaporator

C

Compressor

D

Expansion valve

Question 449 1 Marks

What is the advantage of using capillary tube as an expansion device?

A

Temperature balancing is easy

B

Pressure balancing is easy

C

Volume balancing is easy

D

Complicate design

Question 450 1 Marks

Which method is used to connect the swaged joint in copper tubes?

A

TIG welding

B

Silver brazing

C

Lead soldering

D

Fusion welding

Question 451 1 Marks

Which type of filter drier is used with HFC 134a car AC?

A

XH ? 1

B

XH ? 3

C

XH ? 5

D

XH ? 7

Question 452 1 Marks

Which type of cooling tower is used in large capacity chiller plants?

A

Natural draft

B

Forced draft

C

Induced draft

D

Liquid cooling

Question 453 1 Marks

What is the advantage of inverter split AC?

A

Eliminates compressor

B

High energy efficiency

C

Low energy efficiency

D

Current drawn is high

Question 454 1 Marks

Which law is related to the constant PV at constant T?

A

Boyles law

B

Charles s law

C

Pascal s law

D

Renaults law

Question 455 1 Marks

Which component rejects the maximum heat to ambinet air in refrigerator?

A

Expansion valve

B

Compressor

C

Condenser

D

Evaporator

Question 456 1 Marks

Which property is desirable for an ideal refrigerant?

A

High boiling point

B

High freezing point

C

High specify volume

D

High latent heat value

Question 457 1 Marks

Which lubricant oil is used in swash plate of R 134a compressor?

A

Servo 20

B

POE

C

SAE - 40

D

Mineral oil

Question 458 1 Marks

What is the desirable property of POE lubricant?

A

Hygroscopic

B

Miscible with HFCs

C

Forms acid with moisture

D

Toxic gas produced during brazing

Question 459 1 Marks

Which is the inorganic refrigerant?

A

R 170

B

R 500

C

R 630

D

R 717

Question 460 1 Marks

What is the equivalent of one micron in millimeter?

A

0.0001 mm

B

0.001 mm

C

0.01 mm

D

0.1 mm

Question 461 1 Marks

Which lubricant oil is used with R-134a car AC system?

A

Mineral oil

B

Low viscosity oil

C

High viscosity oil

D

Poly alkylene glycol

Question 462 1 Marks

What is the use of capacitor in PSC
operated induction motor?

A

Decrease the starting torque

B

Cancel the starting torque

C

Improve the power factor

D

Decrease the power factor

Question 463 1 Marks

What is the differential of low pressure cut out control switch? If LPC cuts out at 2.2kg/ cm2 and LPC cut in at 2.4kg/ cm2

A

0.8 kg/ cm2

B

0.4 kg/ cm2

C

0.2 kg/ cm2

D

0.1 kg/ cm2

Question 464 1 Marks

What is the resistance level of start winding in a refrigerator s compressor motor?

A

Medium resistance

B

High resistance

C

Zero resistance

D

Low resistance

Question 465 1 Marks

Which medium is used to extinguish Class - A fire?

A

CO2

B

Foam

C

Water

D

Dry powder

Question 466 1 Marks

What is the equivalvent of 760mm of Hg in torr?

A

7.6 Torr

B

76 Torr

C

760 Torr

D

7600 Torr

Question 467 1 Marks

Which law relates to voltage, current and resistance in an electrical circuit?

A

Ohm s law

B

Lenz s law

C

Newton s law

D

Faraday s law

Question 468 1 Marks

Which type of switch is used to control the room air temperature in split AC?

A

Over load protector

B

Thermostat switch

C

Manual switch

D

Thermal relay

Question 469 1 Marks

What is the composition of oxygen in atmospheric air?

A

0.11

B

0.21

C

0.31

D

0.41

Question 470 1 Marks

Which type of insulating material is used for making ice box to cool beverages?

A

Tar felt

B

Glass wool

C

Fibre glass

D

Thermocole

Question 471 1 Marks

Which device ensures correct flow of chilled water supply in chiller AC plant?

A

Sight glass

B

Leaf switch

C

Level master control

D

Pressure relief valve

Question 472 1 Marks

Which fan is used to handle the direction of air flow 90 Degree away from the inlet?

A

Axial propeller fan

B

Centrifugal blower fan

C

Tube axial propeller fan

D

Vane axial propeller fan

Question 473 1 Marks

What is the use of dehydrator?

A

Absorb oil

B

Absorb heat

C

Absorb refrigerant

D

Absorb moisture

Question 474 1 Marks

Which property is considered for a
temperature range in selecting a lubricant oil?

A

Natural

B

Artificial

C

Viscosity

D

Cost effective

Question 475 1 Marks

What is the name of process that changes the used refrigerant to new product?

A

Recover

B

Recycle

C

Reclaim

D

Manufacture

Question 476 1 Marks

What is the category of R 407c refrigerant?

A

Azeotropes

B

Zeotropes

C

Inorganic

D

Organic

Question 477 1 Marks

What is the test pressure of condenser coils during manufacture?

A

450 psig

B

350 psig

C

250 psig

D

150 psig

Question 478 1 Marks

What is the effect on defective thermostat sensor in split AC?

A

Unit consumes less power

B

Increases super heat

C

AC unit runs continuously

D

Relay malfunctions

Question 479 1 Marks

Which type of defrosting method is used in frost free refrigerator?

A

Hot water defrosting

B

Manual defrosting

C

Hot gas defrosting

D

Electric defrosting

Question 480 1 Marks

Why CFC 12 system is replaced by HFC 134a system in car AC?

A

Increase ODP

B

Increase GWP

C

GWP becomes zero

D

ODP becomes zero

Question 481 1 Marks

Which component defrosts in frost free refrigerator?

A

Bulb

B

Heater

C

Thermostat

D

Capillary tube

Question 482 1 Marks

What is the advantage of multi split air conditioners?

A

One outdoor unit for one indoor unit

B

two outdoor units for one indoor unit

C

Several outdoor units for one indoor unit

D

One outdoor unit for several indoor units

Question 483 1 Marks

Which device is installed in ducts to control air flow?

A

Grille

B

Damper

C

Diffuser

D

Register

Question 484 1 Marks

Which components are connected by metering device in vapour compression cycle?

A

Condenser and evaporator

B

Compressor and condenser

C

Evaporator and suction line

D

Compressor and evaporator

Question 485 1 Marks

What is the velocity range of air circulated in car AC?

A

2 - 3 m / sec

B

5 - 7 m / sec

C

7 - 9 m / sec

D

9 - 10 m / sec

Question 486 1 Marks

Where the liquid refrigerant is stored in multi split Air-conditioner during pump down operation?

A

Evaporator

B

Condenser

C

Accumulator

D

Liquid receiver

Question 487 1 Marks

What is the limitation for DOL starters in package AC?

A

Up to 3 HP

B

Up to 5 HP

C

Up to 8 HP

D

Up to 10 HP

Question 488 1 Marks

Which material is used for making air ducts in chiller AC plant?

A

Cast iron

B

Glass wool

C

Thermo Cole

D

Galvanised iron

Question 489 1 Marks

Which parameters in log sheet indicate the air blocking in ducts?

A

All grille temperatures

B

Liquid line temperature

C

Inlet and outlet temperature of chillier

D

Temperatures in chilled water system

Question 490 1 Marks

Which refrigerant blend is highly flammable?

A

HCFC

B

HFC

C

CFC

D

HC

Question 491 1 Marks

What is the purpose of using rubber pads while installing compressor?

A

Fill gaps

B

Prevent leaks

C

Locate the parts

D

Absorb vibration

Question 492 1 Marks

What is the cause of water leakage in indoor unit of multi split AC?

A

Efficient water pump

B

Drain line not properly installed

C

Condenser water pump defective

D

Over flow of water from cooling tower sump

Question 493 1 Marks

Which is the hydrocarbon refrigerant?

A

R 12

B

R123

C

R 500

D

R 600a

Question 494 1 Marks

What is the effect on adjusting the thermostat differential too close in package AC?

A

Unit does not start

B

Normal cooling effect

C

Unit runs continuously

D

Unit starts and stops frequently

Question 495 1 Marks

Which is the welding method if the filler rod only is fused?

A

Non fusion

B

Pressure

C

Fusion

D

Forge

Question 496 1 Marks

How the ability of a conductor is called if it induces the voltage in the same conductor?

A

Self inductance

B

Conductance

C

Capacitance

D

Resistance

Question 497 1 Marks

How pressure drop is achieved in capillary tube of refrigeration cycle?

A

The friction between refrigerant and tube

B

The friction between refrigerant and oil

C

The friction between piston and cylinder

D

The friction between belt and pulley

Question 498 1 Marks

What is the comfortable range of relative humidity (RH) for human beings?

A

30 +/- 5%

B

40 +/- 5%

C

50 +/- 5%

D

60 +/- 5%

Question 499 1 Marks

What is smothering in fire extinguishing?

A

Pouring of CTC

B

Flashing with dry powder

C

Use water to lower temperature

D

Cutting off oxygen supply to fire

Question 500 1 Marks

Which parameter of air is measured by the thermometer bulb that is wetted in sling psychrometer?

A

Dew point temperature

B

Dry bulb temperature

C

Wet bull temperature

D

Evaporating temperature

Question 501 1 Marks

Which method of refrigeration system is adopted in frost free refrigerator?

A

Vapour compression

B

Vapour absorption

C

Water vapour

D

Evacuating

Question 502 1 Marks

What is the cause for noisy fan motor in outdoor unit of split AC?

A

Bearing worn out

B

Motor Burnt

C

Shaft struck

D

Blade bent

Question 503 1 Marks

What tonnage capacity of split AC unit uses 150/200 MFD starting capacitor?

A

1 TR

B

1.5 TR

C

2.0 TR

D

2.5 TR

Question 504 1 Marks

What is the purpose of gland packing in water line valves of chiller AC plant?

A

Prevent leakage

B

Control water flow

C

Reduce valve noise

D

Smooth handling of valve

Question 505 1 Marks

Which is the accurate method of refrigerant charging in car AC?

A

Weighing method

B

Dial a charge method

C

Suction pressure method

D

Sight glass bubbles method

Question 506 1 Marks

What is the effect on defective thermostat sensor in split AC?

A

Unit consumes less power

B

Increases super heat

C

AC unit runs continuously

D

Relay malfunctions

Question 507 1 Marks

What is the flame temperature range of oxy acetylene gas flame?

A

1800Degree Centigrade to 2200Degree Centigrade

B

2400Degree Centigrade to 2700Degree Centigrade

C

2700Degree Centigrade to 2800Degree Centigrade

D

3100Degree Centigrade to 3300Degree Centigrade

Question 508 1 Marks

Which safety device is used for compressor motor in window air conditioner?

A

Relay

B

Starting capacitor

C

Running capacitor

D

Over load protector

Question 509 1 Marks

What is the cause for noisy fan motor in outdoor unit of split AC?

A

Bearing worn out

B

Motor Burnt

C

Shaft struck

D

Blade bent

Question 510 1 Marks

What does the number 4 of R 134a indicate?

A

Number of hydrogen atoms

B

Number of chlorine atoms

C

Number of carbon atoms

D

Number of fluorine atoms

Question 511 1 Marks

Which terminals are momentarily shorted to start the compressor motor without relay?

A

C and S terminal

B

S and R terminal

C

C and R terminal

D

S and compressor body

Question 512 1 Marks

What is meant by total pressure in a duct?

A

Velocity pressure - static pressure

B

Static pressure + velocity pressure

C

Velocity pressure + suction pressure

D

Suction pressure + discharge pressure

Question 513 1 Marks

Where the manually defrosted water is stored in refrigerator?

A

Tray on top of the compressor

B

Bottom of the evaporator

C

Bottom of the condenser

D

Top of the freezer

Question 514 1 Marks

Which is circulated in VRV system for cooling cycle?

A

Water

B

Cooled air

C

Cooled brine

D

Liquid refrigerant

Question 515 1 Marks

Which device equalizes the pressure between low and high side of split AC during ?OFF? cycle?

A

Suction tube

B

Copper tube

C

Capillary tube

D

Discharge tube

Question 516 1 Marks

Why frost free model refrigerator takes less freezing time of products?

A

Forced air circulation

B

Natural air circulation

C

Low temperature setting

D

High temperature setting

Question 517 1 Marks

Which application uses the capillary tube expansion device?

A

Domestic RAC units

B

Industrial ice plants

C

Commercial AC plants

D

Hospital IAQ systems

Question 518 1 Marks

Which bearing is used in blower motor of indoor unit in ductable split air conditioner?

A

Ball bearing

B

Thrust bearing

C

Sleeve bearing

D

Open ball bearing

Question 519 1 Marks

Which is the constant reference for the working of AEV?

A

Oil temperature

B

Suction pressure

C

Volume expansion

D

Discharge pressure

Question 520 1 Marks

Which component controls the thermostat and defrost heater in frost free refrigerator?

A

Thermoheater

B

Defrost timer

C

Relay

D

OLP

Question 521 1 Marks

Which motor is used to drive the blower of indoor unit in ductable split air conditioners?

A

Shaded pole motor

B

Permanent split capacitor motor

C

Three phase induction motor

D

Capacitor start capacitor run motor

Question 522 1 Marks

What is the area of room cooled by 1ton window air conditioner?

A

5000 sq.ft

B

2000 sq.ft

C

1000 sq.ft

D

3000 sq.ft

Question 523 1 Marks

How the level of heat in a substance is
expressed?

A

Micron

B

Pressure

C

Humidity

D

Temperature

Question 524 1 Marks

Which distribution system is absent in VRV operation compared to central AC plant?

A

Refrigeration

B

Ducting system

C

Refrigerant flow

D

Interlocked wiring

Question 525 1 Marks

Which part of a central AC system cannot be repaired after pump down operation?

A

Condenser

B

Evaporator

C

Liquid receiver

D

Expansion device

Question 526 1 Marks

Which materials are used to make mallets?

A

Wood, cast iron

B

Wood, rubber

C

Rubber, brass

D

Wood, brass

Question 527 1 Marks

What is the cause of compressor knocking sound in chiller AC plant?

A

High oil level

B

Liquid refrigerant entry

C

Shortage of refrigerant

D

Air entered into system

Question 528 1 Marks

What is starving in extinguishing the fire?

A

Adding fuel

B

Removal of fuel

C

Clearing the hazards

D

Stop the supply of oxygen

Question 529 1 Marks

Which causes the filter drier to become cold in chiller AC plant?

A

Over charge

B

Under charge

C

High condensing pressure

D

Partial blocking of filter drier

Question 530 1 Marks

What is the cause of high condensing pressure in water cooled condenser?

A

Lack of lubrication

B

Damage condenser fan

C

Low load on evaporator

D

Defective cooling water pump

Question 531 1 Marks

What is the storage capacity of oxygen cylinder?

A

3 m3

B

5 m3

C

6 m3

D

7 m3

Question 532 1 Marks

What is the purpose of air filter?

A

Cool air

B

Circulate air

C

Ensure clean air

D

Improve performance

Question 533 1 Marks

Which control opens the compressor motor circuit in the event of continuous overload?

A

Thermostat

B

Fusible plug

C

Bimetal strip

D

Spring loaded relief valve

Question 534 1 Marks

Where the relay coil is internally connected in voltage relay?

A

Across 1 and 2

B

Across 5 and 1

C

Across 5 and 2

D

Across 2 and 4

Question 535 1 Marks

What is the reason for air conditioner running continuously but no cooling effect ?

A

Condensation poor

B

Refrigerant is more

C

Refrigerant leaked

D

Over charged oil

Question 536 1 Marks

Which type of pump is used in AC plants
for circulation of chilled water?

A

Gear

B

Screw

C

Rotary

D

Centrifugal

Question 537 1 Marks

What is the method of converting AC to DC
power supply with two diodes and a step down
transformer?

A

Bridge rectifier

B

Full wave rectifier

C

Half wave rectifier

D

Medium wave rectifier

Question 538 1 Marks

Which refrigerant property is desirable for V.C system?

A

Low boiling point

B

Corrosive to metals

C

Low latent heat valve

D

Low Dielectric strength

Question 539 1 Marks

Which thermodynamic process the temperature is kept constant?

A

Isobaric process

B

Isothermal process

C

Constant volume process

D

Constant pressure process

Question 540 1 Marks

What is the reason for short cycling of LP control switch in AC plant?

A

Excess of water flow

B

Excess of refrigerant

C

Shortage of water flow

D

Shortage of refrigerant

Question 541 1 Marks

What is the reverse break down voltage range of zener diode?

A

0.1 to 0.5 volt

B

0.5 to 1 volt

C

3 to 18 volt

D

1 to 3 volt

Question 542 1 Marks

What is the reason for no cooling in a frost
free refrigerator?

A

Defective fan motor

B

Open door switch

C

High watt Cabinet bulb

D

Defective timer

Question 543 1 Marks

Which two components do the compressor function in vapour absorption system?

A

Generator and absorber

B

Generator and separator

C

Generator and condenser

D

Generator and evaporator

Question 544 1 Marks

Which control opens the compressor motor circuit in the event of continuous overload?

A

Thermostat

B

Fusible plug

C

Bimetal strip

D

Spring loaded relief valve

Question 545 1 Marks

Which colour is used for painting condenser coil?

A

Green

B

Black

C

Blue

D

Red

Question 546 1 Marks

What is the periodical checking for blower belt in package AC?

A

Daily

B

Yearly

C

Weekly

D

Monthly

Question 547 1 Marks

What is the total resistance if two resistors R1 and R2 are connected in series?

A

(R1 - R2) Ohms

B

(R1 + R2) Ohms

C

(R1 x R2) Ohms

D

(R1 / R2) Ohms

Question 548 1 Marks

Which valve is closed first while extinguishing flame in gas welding process?

A

Acetylene

B

Hydrogen

C

Oxygen

D

Air

Question 549 1 Marks

What type of heat is absorbed by primary refrigerant?

A

Total heat

B

Latent heat

C

Specific heat

D

Sensible heat

Question 550 1 Marks

Which valve is first closed to start the pump down operation in central AC plant?

A

Receiver inlet valve

B

Receiver outlet valve

C

Suction service valve

D

Discharge service valve

Question 551 1 Marks

How the pressure drop of refrigerant flow is minimised during installation of indoor and outdoor units in ductable split AC?

A

Pipe lines with more joints

B

With more horizontal distance

C

System pipes with minimum bends

D

Install units as far as possible

Question 552 1 Marks

Which power supply has the fixed polarity?

A

Direct current

B

Signal voltage

C

Signal ripples

D

Alternating current

Question 553 1 Marks

Which is the green house gas?

A

Oxygen of atmospheric air

B

Chlorofluoro carbon in air

C

Helium of atmospheric air

D

Neon of atmospheric air

Question 554 1 Marks

Which suction line pressure ensures that the compressor is to be stopped during pump down operation?

A

3 kg/cm2

B

5 kg/cm2

C

0.5 kg/cm2

D

(- 0.5 kg/cm2)

Question 555 1 Marks

What is the effect of longer suction and liquid piping in AC?

A

No pressure rise

B

More pressure drop

C

Less pressure drop

D

Medium pressure rise

Question 556 1 Marks

Which device equalizes the system pressure in frost free refrigerator?

A

Capillary tube

B

Compressor

C

Condenser

D

Evaporator

Question 557 1 Marks

What is the remedy for broken bimetal thermo in a frost free refrigerator?

A

Repair the bimetal thermo

B

Reuse the bimetal thermo

C

Replace the bimetal thermo

D

Readjust the bimetal thermo

Question 558 1 Marks

Which winding has high inductance value in CSR compressor motor?

A

Common winding

B

Running winding

C

Starting winding

D

Auxiliary winding

Question 559 1 Marks

What is the condition of compressor motor if Ohm meter reads infinity across common and start terminals?

A

Running winding open

B

Starting winding open

C

Starting winding shorted

D

Running winding shorted

Question 560 1 Marks

Which is disconnected by centrifugal switch is RSIR motor?

A

Running winding

B

Common winding

C

Starting winding

D

Running capacitor

Question 561 1 Marks

Where the thermal bulb is fixed in frost free refrigerator?

A

Liquid line

B

Discharge line

C

Last coil of condenser

D

Last coil of evaporator

Question 562 1 Marks

Why the temperatures of inlet and outlet water in shell and tube condenser are recorded in log sheet?

A

Study about the plant

B

Judge quality of water

C

Checking the hardness of water

D

Fix descaling time for condenser

Question 563 1 Marks

What is the reason for poor condensation in split AC?

A

High ambient temperature

B

Low ambient temperature

C

Condenser tube leaky

D

Blower motor failure

Question 564 1 Marks

Which safety control is electrically connected in series with magnetic clutch of compressor in car AC?

A

TEV

B

AEV

C

HPC

D

EEV

Question 565 1 Marks

What is the purpose of operating the fan motor first and then the compressor motor in Air conditioners?

A

Cool the coils first by fan

B

Cool the compressor by fan

C

Minimise the noise of motors

D

Stop the high starting current by both motors

Question 566 1 Marks

Which tool is used for bending long sheet metal?

A

Folding bar

B

Bench vice

C

Hand vice

D

Shear

Question 567 1 Marks

Which type of compressor is used as a vacuum pump?

A

Reciprocating

B

Centrifugal

C

Rotary

D

Scroll

Question 568 1 Marks

Which capacitor is connected in series with starting winding of CSR motor during operation?

A

Fan capacitor|

B

Run capacitor

C

Start capacitor

D

No capacitor is connected

Question 569 1 Marks

What is the full form of the relay - PTC?

A

Positive temperature coefficient

B

Permanent temperature control

C

Polar terminal checking

D

Positive terminal circuit

Question 570 1 Marks

What is the remedy for loosened one belt in multidrive belts of blower unit?

A

Align the drive pully

B

Align the driven pully

C

Remove the loosened one

D

Replace the whole set of belts

Question 571 1 Marks

Which winding is made of thick wire in single phase induction motor?

A

Starting

B

Running

C

Auxiliary

D

Additional

Question 572 1 Marks

Which tool is used for trimming the edges of a sheet metal cylinder?

A

Straight snips

B

Bent snips

C

Tube cutter

D

Scissors

Question 573 1 Marks

What is the effect of pouring water on electrodes resistance in earth pit?

A

Decreases

B

Increases

C

Equalises

D

Remains same

Question 574 1 Marks

What is the cause of discolouration of oil in a compressor?

A

Moisture in oil

B

Dirty drier filter

C

Low pressure of oil

D

Liquid refrigerant in oil

Question 575 1 Marks

Which movement of the scroll compresses the low pressure vapour in scroll compressor?

A

Reciprocating

B

Centrifugal

C

Rotating

D

Orbital

Question 576 1 Marks

Which control terminals are shorted before pump down operation in package AC?

A

Selector switch

B

H.P cut-out switch

C

L.P cut-out switch

D

Thermostat switch

Question 577 1 Marks

Which metal is alloyed with zinc to make brass?

A

Iron

B

Copper

C

Bronze

D

Aluminium

Question 578 1 Marks

Which motor is used to drive the condenser fan of out-door unit in ductable split air conditioner?

A

Capacitor start capacitor run motor

B

Three phase induction motor

C

Permanent split motor (PSC)

D

Shaded pole motor

Question 579 1 Marks

Which is indicated by the arrow mark on filter drier component?

A

Flow direction of air

B

Position of capillary tube

C

Flow direction of refrigerant

D

Arrangement of desiccant and filter

Question 580 1 Marks

What is the reason for frost accumulation in
between fins and tubes of evaporator in frost free
refrigerator?

A

Under charge of refrigerant

B

Over charge of refrigerant

C

Defective fan motor

D

Defective timer

Question 581 1 Marks

What is the cause for noise in indoor unit of a multi split air conditioner?

A

Refrigerant leak

B

Blower is loosened

C

Running current is high

D

Compressor not working

Question 582 1 Marks

What is the purpose of valves in chiller AC plants?

A

Removes dust

B

Control air flow

C

Increase pressure

D

Regulate the flow of water

Question 583 1 Marks

What is bottom dead centre in reciprocating compressor cylinder?

A

The piston moves up from the point of cylinder

B

The piston stops in cylinder at top

C

The piston moves down from the point of cylinder

D

The piston starts in cylinder at top

Question 584 1 Marks

What is the fault in compressor motor if there is electrical continuity between the dome and motor terminal?

A

Shorted run winding

B

Open common terminal

C

Shorted start winding

D

Grounded compressor motor

Question 585 1 Marks

Which colour code indicates the earth wire in power supply cord?

A

Red

B

Black

C

Brown

D

Green/yellow

Question 586 1 Marks

Which type of expansion valve is used in window air conditioner?

A

Capillary tube

B

Low side float valve

C

Automatic expansion valve

D

Thermostatic expansion valve

Question 587 1 Marks

What is the cause of bubbles in liquid line sight glass after gas charging the system?

A

Excess refrigerant

B

Shortage of refrigerant

C

Oil bubbles in sight glass

D

Nitrogen trapped in system

Question 588 1 Marks

What is the effect of pressure drop at the inlet of the evaporator?

A

Flashing of liquid refrigerant

B

Freezing of liquid refrigerant

C

Freezing of liquid

D

Boiling of oil

Question 589 1 Marks

What is the advantage of water pressure cut out switch in package AC?

A

Raise condensation

B

Improve evaporation

C

Protect the compressor

D

Increase refrigerant flow

Question 590 1 Marks

Which type of AC system is capable of heating or cooling in different zones simultaneously?

A

Package AC

B

Central plant AC

C

VRV AC system

D

VAV AC system

Question 591 1 Marks

Why the LP cut out control is bypassed electrically before pump down operation?

A

Avoid oil foaming

B

Prevent liquid entry to compressor

C

Increase current of the compressor motor

D

To lower the suction pressure close to 0.5 kg/cm2

Question 592 1 Marks

Which RAC system belongs to centralised air conditioning?

A

Split AC

B

Window AC

C

Cassette AC

D

Chiller plant AC

Question 593 1 Marks

What is the temperature maintained in the refrigerator freezer?

A

0 Degree Centigrade

B

- 15 Degree Centigrade

C

- 45 Degree Centigrade

D

- 65 Degree Centigrade

Question 594 1 Marks

Which set of components are used in FCU?

A

Air filter, blower, condenser

B

Compressor, fan, condenser

C

Air filter, cooling coil, blower motor

D

Cooling coil, condenser, fan motor

Question 595 1 Marks

Which refrigerant spreads the pungent odour if it leaks from ice plant system?

A

H2O

B

SO2

C

CO2

D

NH3

Question 596 1 Marks

What is the tool used for holding hot metals?

A

Tongs

B

Spanner

C

Pipe vice

D

Bench vice

Question 597 1 Marks

Which type of AC system is operated by VRV system?

A

Package AC

B

Central plant AC

C

Multizone split ACs

D

Indirect ACs

Question 598 1 Marks

Which tool is used for bending, seaming and forming of sheet metal?

A

Bench vice

B

Hand vice

C

Stakes

D

Shear

Question 599 1 Marks

What is meant by static pressure?

A

Moving air pressure

B

Ambient air pressure

C

Air diffusing pressure

D

Still air pressure in duct

Question 600 1 Marks

Which process is done to remove the oil and other impurities from the condenser tubes?

A

Purging

B

Flushing

C

Evacuation

D

Pressurising

Question 601 1 Marks

Which position is safe for storing refrigerant cylinder?

A

Upside down

B

Horizontal

C

Inclined

D

Upright

Question 602 1 Marks

Why the miscibility of refrigerant and oil is preferred in car AC?

A

Lubricate the clutch assembly

B

Lubricate the heat exchangers

C

Circulate oil back to compressor

D

Lubricate the moving parts of TEV

Question 603 1 Marks

How the pressure drop of refrigerant flow is minimised during installation of indoor and outdoor units in ductable split AC?

A

Pipe lines with more joints

B

With more horizontal distance

C

System pipes with minimum bends

D

Install units as far as possible

Question 604 1 Marks

What is the purpose of evacuating the system before gas charging?

A

Flush oil particles

B

Charge refrigerant

C

Remove refrigerant

D

Remove moisture and non-condensable

Question 605 1 Marks

What is the reason for having 2.5 kg/cm2 on low and high side of car AC system?

A

Defective thermostat

B

Excessive oil in evaporator

C

Too close differential in LPC

D

Defective compressor valve

Question 606 1 Marks

What is the reason for poor compression?

A

Less clearance volume

B

Scratches on the piston surface

C

Lapped valve plate and reed seat

D

Good lubrication on the moving parts

Question 607 1 Marks

What is the volume of air passed at the outlet of a rectangular duct whose area of cross section is 1m2 and the air velocity by an anemometer is 10m/min?|

A

5 m3

B

10 m3

C

15 m3

D

20 m3

Question 608 1 Marks

Which secondary refrigerant is used for
human comfort in chiller plant AC?

A

Brine

B

Water

C

Ammonia

D

Ethylene glycol

Question 609 1 Marks

Which motor is used to drive the blower of indoor unit in ductable split air conditioners?

A

Shaded pole motor

B

Permanent split capacitor motor

C

Three phase induction motor

D

Capacitor start capacitor run motor

Question 610 1 Marks

What is indicated by the bubbles in car AC's sight glass?

A

Pressure of air

B

Poor compression

C

Excess of refrigerant

D

Shortage of refrigerant

Question 611 1 Marks

What is the use of a starting capacitor in single phase induction motor?

A

Improve power factor

B

Increase starting torque

C

Decrease starting torque

D

Dis connect starting winding

Question 612 1 Marks

How long the filter drier unit is used in car AC?

A

1 year

B

2 years

C

3 years

D

4 years

Question 613 1 Marks

Which speed is recommended for checking optimum performance in car AC?

A

1600 rpm

B

2600 rpm

C

3600 rpm

D

4600 rpm

Question 614 1 Marks

Which property limits the flow of electrons in an electrical circuit?

A

Voltage

B

Current

C

Resistance

D

Conductance

Question 615 1 Marks

Which type of heat is absorbed by water while passing through the cooling coils of an indirect expansion chiller plant?

A

Super heat

B

Latent heat

C

Specific heat

D

Sensible heat

Question 616 1 Marks

Which is the constant operating condition of TEV?

A

Super heat at suction line point

B

Evaporator pressure at its inlet

C

Enthalpy at the evaporator outlet

D

Entropy at the condenser outlet

Question 617 1 Marks

What is the advantage of electrically interlocked circuit for motors and pumps in a chiller plant?

A

Start the loads non sequentially

B

Start the loads when not needed

C

Stop the loads when not required

D

Start and stop the loads sequentially

Question 618 1 Marks

Which horizontal distance is preferred between indoor and outdoor units in ductable split AC installation?

A

15 meters

B

12 meters

C

20 meters

D

25 meters

Question 619 1 Marks

Which instrument is used to measure atmospheric pressure?

A

Hygrometer

B

Hydrometer

C

Manometer

D

Barometer

Question 620 1 Marks

What is the physical change of refrigerant in evaporator?

A

Solid to liquid

B

Vapour to solid

C

Liquid to vapour

D

Vapour to liquid

Question 621 1 Marks

Which tool is used to straighten the deformed fins of air cooled condenser?

A

Blower

B

Fin comb

C

Wire brush

D

Brass brush

Question 622 1 Marks

What is the minimum quantity of fresh air needed per person in comfort AC?

A

3 to 4.5 cfm

B

4 to 5.5 cfm

C

5 to 7.5 cfm

D

2 to 3.5 cfm

Question 623 1 Marks

What is the preventive maintenance of cooling tower sump?

A

Remove sludge

B

Flush with water

C

Add HCL to water

D

Add bleaching powder

Question 624 1 Marks

What is the advantage of variable speed pumping load control in chiller AC plant?

A

Heating control is easy

B

High cost of maintenance

C

Control valves are eliminated

D

Cooling coil can be eliminated

Question 625 1 Marks

Which size service port is used in automobile air conditioners for HFC-134a refrigerant?

A

1/4" - 13 ACME

B

1/2" - 16 ACME

C

3/8" - 15 ACME

D

5/16" - 14 ACME

Question 626 1 Marks

Which gas is used for flushing blocked capillary tube?

A

Moist air

B

Hydrogen

C

Dry nitrogen

D

Aqua ammonia

Question 627 1 Marks

Which process is done first in split AC for shifting from one place to another?

A

Flushing

B

Evacuation

C

Pump down

D

Vacuumisation

Question 628 1 Marks

What is the minimum temperature difference in water required between inlet and outlet of water cooled condenser?

A

5 Degree Centigrade

B

15 Degree Centigrade

C

10 Degree Centigrade

D

20 Degree Centigrade

Question 629 1 Marks

What is the effect on compressor motor if water pressure switch trips out in package AC?

A

Does not stop

B

Stops working

C

Does not start

D

Motor burns out

Question 630 1 Marks

Which is eliminated from the system in
vacuumising process?

A

Humidity

B

Moisture

C

Pressure

D

Temperature

Question 631 1 Marks

What is the fault if excess deposit of tiny metal globules formed on the job surface along weld?

A

Incomplete penetration

B

Slag inclusion

C

Blow hole

D

Spatters

Question 632 1 Marks

Which type of insulation material is used in modern refrigerators?

A

Saw dust

B

Glass wool

C

Thermocole

D

Poly urethane foam

Question 633 1 Marks

Which control switch is connected in series with magnetic clutch in Car AC wiring?

A

Piston pin

B

Thermostat control

C

Automatic expansion valve

D

Thermostatic expansion valve

Question 634 1 Marks

What is the value of running capacitor used for 1.5 TR window air conditioner?

A

36 MFD

B

40 MFD

C

80 MFD

D

100 MFD

Question 635 1 Marks

Why evaporator of air conditioner has more fins per inch?

A

Increase the air contact

B

Increase the water dripping

C

Decrease the air circulation

D

Produce more ice

Question 636 1 Marks

How the maximum reverse voltage across the diode is termed in reverse biased condition?

A

Diode voltage

B

Ripple frequency

C

Peak inverse voltage

D

Peak rectification voltage

Question 637 1 Marks

How many water drain lines are provided for each evaporator in a bus AC?

A

One

B

Two

C

Three

D

Four

Question 638 1 Marks

How the refrigerants are classified based on heat absorption by latent and sensible heat?

A

Primary and secondary

B

Organic and inorganic

C

Zeotropic and azeotropic

D

Halocarbons and hydrocarbons

Question 639 1 Marks

Which substance absorbs heat and directly changes its state from solid to vapour?

A

Ice

B

Dry ice

C

Primary refrigerants

D

Secondary refrigerants

Question 640 1 Marks

Which safety control stops the compressor motor if there is leakage of refrigerant?

A

LP cut out

B

HP cut out

C

Thermostat

D

Oil pressure cut out

Question 641 1 Marks

Which material is used for making service valve?

A

Brass

B

Cast iron

C

Aluminium

D

Stainless steel

Question 642 1 Marks

What is the evaporator surface temperature maintained in dehumidifier?

A

Above dry bulb temperature of air

B

Below dry bulb temperature of air

C

Above dew point temperature of air

D

Below dew point temperature of air

Question 643 1 Marks

Why universal numbering system is adopted for different refrigerants?

A

Identifying the refrigerant's names

B

Mixing the lubricant combination

C

Fixing the drier combination

D

Identify the systems

Question 644 1 Marks

Which component absorbs heat from return air in package AC?

A

Blower

B

Condenser

C

Evaporator

D

Expansion valve

Question 645 1 Marks

What parameters are checked if the uneven cooling prevails at different rooms in a chiller plant?

A

Compressor current drawn

B

Condenser water pump ampere

C

Cooling tower fan motor ampere

D

Chilled water pump current drawn

Question 646 1 Marks

What is the purpose of providing gas ballast in two stage rotary vacuum pump?

A

Avoid condensation of water vapour

B

Prevent condensation of nitrogen

C

Prevent condensation of dry air

D

Avoid condensation of refrigerant

Question 647 1 Marks

What is the type of condenser used in direct cool refrigerator?

A

Fin and tube

B

Shell and tube

C

Wire mesh

D

Tube in tube

Question 648 1 Marks

Which branch of science deals with the properties of air?

A

Geometry

B

Audiometry

C

Psychrometry

D

Trigonometry

Question 649 1 Marks

What is the expansion of PMV used in VRV system?

A

Prime Mover Valve

B

Pass Modulate Valve

C

Phase Modulate Valve

D

Pulse Modulating Valve

Question 650 1 Marks

What is the use of anemometer?

A

Check water flow

B

Measure air flow

C

Produce current

D

Measure voltage

Question 651 1 Marks

What is the effect of operating the compressor under 5 of Hg vacuum during pump down process?

A

Pumps oil to condenser

B

Prevent motor damage in dome

C

Prevent leakage in service valve

D

Prevent piston damage

Question 652 1 Marks

Which device switches ON/OFF the car AC compressor?

A

Crank shaft

B

Blower unit

C

Rotor winding

D

Magnetic clutch

Question 653 1 Marks

Which component secures the hose with regulator union in gas welding set?

A

Steel wire

B

Hose clamp

C

Fibre clip

D

Iron chain

Question 654 1 Marks

Which insulating material is used in duct work?

A

Wood

B

Plastic

C

Rubber

D

Glass wool

Question 655 1 Marks

What is the reason if refrigerator runs normally but no cooling effect?

A

Leakage of refrigerant

B

Condenser block

C

Filter block

D

Over charge

Question 656 1 Marks

What is the boiling point of HFC-134a refrigerant at atmospheric pressure?

A

-26.1 Degree Centigrade

B

-25.6 Degree Centigrade

C

-24.5 Degree Centigrade

D

-23.6 Degree Centigrade

Question 657 1 Marks

What is the reason for the compressor does not start but the fan motor works normally in window AC?

A

Defective blower

B

Defective fan motor

C

Defective fan capacitor

D

Defective compressor motor

Question 658 1 Marks

What is the name of the caliper having one leg with an adjustable divider point and other leg is bent?

A

Jenny Caliper

B

Inside Caliper

C

Outside caliper

D

Spring joint caliper

Question 659 1 Marks

What is the ampere setting for 3.5 mm diameter electrode in welding?

A

50 Ampere

B

60 Ampere

C

100 Ampere

D

110 Ampere

Question 660 1 Marks

What is the function of starting capacitor in CSIR motor?

A

Gives initial torque

B

Gives running torque

C

Corrects power factor

D

Improves energy efficiency

What is the method of starting a 3 phase slip ring induction motor?

What is the atmospheric pressure at sea level?

Which safety control is manually reset after rectifying the faults in packages AC?

Which type of evaporator is used in frost free refrigerator?

What is the function of remote control in split AC?

Why the idler pulley is used in belt driven car AC?

Which component belongs to outdoor unit of split AC?

What is the reason for switching contacts get carbonised in package AC electrical wiring?

Which movement of plunger energises the start winding in relay operation?

Which two tubes act as heat exchanger in a refrigerator?

Which sheet is used to check the tigtness of door gasket of a refrigerator?

What is the advantage of using flux in brazing?

Which type of compressor is used in window air conditioner?

What is top dead centre in reciprocating compressor cylinder?

What is the temperature of air at the supply grille in car AC system at an ambient 35 Degree Centigrade?

How the power consumed by the motor varies with its speed in VFD?

What is the advantage of using indirect expansion chiller AC system?

Which type of switch is used to control the room air temperature in split AC?

What is the purpose of relay used in window air conditioner?

Which valve is used for gas charging and pressure checking in central AC plants?

Which type fan blade is used with out door unit of split AC?

Which instrument is used to measure the velocity pressure of air in ducting system?

Which capacitor is disconnected by relay in capacitor start and induction run motor?

What is the reason for intermittent cooling cycle in car AC?

How many fan motors are used in split AC?

What is the effect of moist air present inside the hermetic system?

How many hydrogen atoms are present in R 134a?

What is the rate of doing work?

Which operation is carried out first in selector switch after installation of package AC?

Which psychometric process takes place if the air is passed through hygroscopic chemicals?

What is the equivalent absolute scale for centigrade?

What is the name of electronic circuit?

Which type of fan blade is used with indoor unit?

Which type fan blade is used with out door unit of split AC?

What is the function of remote control in split AC?

Which motor has the least starting torque?

Which component switches ON/OFF the starting winding in RSIR motor?

Which system maintains indoor air quality by adding fresh air and conditioned air to offset heating or cooling loads?

What is the ratio of oxygen to acetylene in neutral flame for brazing?

Which is adjusted to the size of electrode in welding process?

Which gauge is connected to the AC plant system before doing pump down operation?

What is the pH level of water used for final rinsing of condenser tubes after descaling?

What is the remedy for defective heating element in a frost free refrigerator?

What is effect of compression process on refrigerant vapour?

What is the physical condition of refrigerant in hermetic dome of rotary compressor?

Why the acetylene gas is avoided with copper pipe lines or fittings in oxy-acetylene welding set?

What is the preventive remedy for scale in water cooled condenser tubes in package AC?

How many fan motors are used in split AC?

What is the function of starting capacitor in CSIR motor?

What is the reason for poor cooling effect in multi split air conditioner?

Which group the acetylene gas belongs?

What is the purpose of chemical spraying on finned condenser?

Which operating condition opens the HPC control switch in car AC?

Which design data is used for indoor air heating in winter air conditioning?

What is the effect of residual acid particles after descaling the shell and tube condenser in industrial AC plant?

What is the effect of scale formation inside the tubes of chiller in industrial AC plant?

Which controls the speed of blower fan motor to vary air cooling or heating in car AC?

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

What is the reason for swash plate compressor failure in car AC?

Which two terminals read the highest resistance while testing refrigerator compressor motor?

What is the effect if the oil return from oil separator to the compressor is blocked?

What is the rotor speed with respect to stator field speed in an induction motor?

What is the reason for filter drier sweating in refrigerator?

What is the name of active component used in electronic circuit?

What is the purpose of rinsing the condenser tubes with water after descaling process in industrial AC plant?

Which device engages the compressor shaft in car AC?

What is the use of magnetic clutch in Car AC?

Which flame is used for welding brass?

Which causes the clogged orifice in TEV of car AC system?

What is applied to find the leakage on acetylene gas connection?

Which tool is used for descaling the condenser tubes in shell and tube condenser?

Which expansion device is used with VFD motors in multi split AC?

What is the remedy to remove moisture from the window AC system?

Which component belongs to indoor unit of split AC?

How the brine freezing on cooling coil is prevented in ice plant?

What is the cause of water hammer or valve chatter in water pump lines?

Where the refrigerant is stored in split AC during pump down operation?

What is the cooling capacity of 1 TR in K Cal / hr?

What is the safety device used during arc welding?

What is the atmospheric pressure at sea
level?

What is the name of electronic
circuit?

Which motor has the least starting
torque?

What is the pH level of water used for final
rinsing of condenser tubes after descaling?

What is the physical condition of refrigerant
in hermetic dome of rotary compressor?

Which device is used to measure the
density of brine solution?

How the difference between the
synchronous speed and the actual rotor speed is
specified?

Which safety device is attached to nitrogen
cylinder?

Which application uses the digital
ICs?

What is the melting temperature of silver
brazing rod?

What are the causes for blockage in
capillary tube?

Which instrument is used to identify the
terminals of a compressor motor?