500+ Maintenance Engineer Interview Questions and Answers

The refrigeration cycle used in a chilling plant is typically the vapor compression cycle.

• The vapor compression cycle involves compressing refrigerant vapor to increase its temperature and pressure.

• The high-pressure vapor then condenses into a liquid, releasing heat.

• The liquid refrigerant then passes through an expansion valve, reducing its pressure and temperature.

• The low-pressure liquid then evaporates, absorbing heat and cooling the surrounding area.

• This cycle is commonly ...read more

Heat treatment of metals involves processes like hardening, tumbling, and tempering. Various equipment and testing methods are used.

• Processes involved in heat treatment: hardening, tumbling, and tempering

• Equipment used: furnaces, quenching tanks, tempering ovens

• Temperature settings for desired hardness quality vary depending on the metal

• Testing methods for hardness: Rockwell hardness test, Brinell hardness test

• Hardening operation involves heating the metal above its critical ...read more

Hydraulic pressure is measured in bar and NAC is not a commonly used term in this context.

• Hydraulic pressure is typically measured in bar or psi

• The amount of pressure required depends on the specific system and application

• NAC is not a commonly used term in the context of hydraulic systems

There are several types of valves in instrumentation.

• Gate valve

• Ball valve

• Butterfly valve

• Globe valve

• Check valve

• Diaphragm valve

• Needle valve

• Plug valve

• Pressure relief valve

• Safety valve

Air fuel ratio in boiler is the ratio of mass of air to mass of fuel. It is maintained by adjusting the fuel and air flow rates.

• Air fuel ratio is critical for efficient combustion and minimizing emissions.

• The ideal air fuel ratio for a boiler is typically between 1.5 and 2.5.

• To maintain the air fuel ratio, the fuel and air flow rates must be adjusted based on the boiler load and combustion conditions.

• Excess air can lead to energy waste and increased emissions, while insuffici...read more

Noise from high tension lines is caused by electromagnetic interference and corona discharge.

• High tension lines carry high voltage electricity, which can cause electromagnetic interference.

• Electromagnetic interference can generate noise in nearby electronic devices and equipment.

• Corona discharge occurs when the electric field surrounding the high tension line ionizes the air, creating a buzzing or crackling sound.

• Corona discharge can also produce radio frequency interference,...read more

Heat transfer is the movement of thermal energy from one object to another. There are three modes of heat transfer: conduction, convection, and radiation.

• Conduction is the transfer of heat through a material without any movement of the material itself. Example: Touching a hot stove.

• Convection is the transfer of heat through the movement of fluids (liquids or gases). Example: Boiling water.

• Radiation is the transfer of heat through electromagnetic waves. Example: Feeling the wa...read more

I maintain the jio tower site by conducting regular inspections, performing preventive maintenance, and addressing any issues promptly.

• Conduct regular inspections to identify any potential issues or maintenance needs

• Perform preventive maintenance tasks such as cleaning, lubricating, and replacing parts

• Address any issues or repairs promptly to minimize downtime

• Keep detailed records of maintenance activities and equipment performance

• Coordinate with other team members and contra...read more

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction.

• Transformers work on the principle of electromagnetic induction.

• They consist of two or more coils of wire, known as windings, which are wound around a core made of magnetic material.

• When an alternating current (AC) flows through the primary winding, it creates a changing magnetic field in the core.

• This changing magnetic field induces a voltage ...read more

Yes, I have extensive knowledge in maintaining rotary equipment.

• I have experience in maintaining rotary pumps, compressors, and turbines.

• I am familiar with troubleshooting and repairing rotary equipment.

• I have knowledge in performing preventive maintenance on rotary equipment.

• I am skilled in reading and interpreting technical manuals and schematics.

• I have worked with various types of rotary equipment such as positive displacement pumps, centrifugal pumps, and screw compressor...read more

Yes, chemical treatment is done in cooling tower to prevent scaling, corrosion and biological growth.

• Chemicals like biocides, scale inhibitors and corrosion inhibitors are added to the water in cooling tower.

• Biocides are used to prevent the growth of bacteria, algae and fungi.

• Scale inhibitors are used to prevent the formation of mineral deposits on the tower walls and heat exchangers.

• Corrosion inhibitors are used to prevent the corrosion of metal components in the tower.

• The t...read more

Yes, I have knowledge and experience in moulding, machine installation and commissioning, and handling utility and HT department during breakdowns.

• I have experience in working with moulding machines and can handle them efficiently.

• I am well-versed with the installation and commissioning of machines and can ensure their proper alignment.

• I have experience in handling utility and HT departments during breakdowns and can troubleshoot and resolve issues effectively.

• I am familiar w...read more

Maintenance involves the activities required to keep equipment, machinery, and facilities in good working condition.

• Maintenance includes preventive maintenance, corrective maintenance, and predictive maintenance.

• Preventive maintenance involves regularly scheduled inspections, cleaning, and servicing to prevent breakdowns.

• Corrective maintenance involves repairing or replacing faulty equipment or components.

• Predictive maintenance uses data and analytics to anticipate and addres...read more

Various equipments are used in pharmaceutical industries for different purposes.

• Mixers and blenders for mixing ingredients

• Filtration systems for purifying liquids

• Centrifuges for separating solids from liquids

• Autoclaves for sterilizing equipment

• Tablet presses for manufacturing tablets

• Capsule filling machines for filling capsules

• Packaging machines for packaging finished products

• HVAC systems for maintaining controlled environments

• Water purification systems for producing purified...read more

Parameters to consider when building a cooling tower

• Size and capacity requirements

• Location and environmental factors

• Design and construction materials

• Water source and quality

• Cooling tower type and configuration

• Safety and regulatory compliance

The hydraulic pack pressure varies depending on the specific system and application.

• Hydraulic pack pressure is the force exerted by the hydraulic fluid in a hydraulic system.

• It is typically measured in pounds per square inch (psi) or bar.

• The pressure can vary based on the load requirements, system design, and component specifications.

• Higher pressure is often required for heavy-duty applications, while lower pressure may be sufficient for lighter tasks.

• For example, a hydraulic...read more

Answering questions related to conveyor calculation, plunger pump, negative pressure, and ballmill troubleshooting.

• Conveyor calculation involves determining the belt speed, capacity, and power requirements.

• A plunger pump works by using a reciprocating plunger to move fluid through a cylinder.

• Negative pressure is a pressure that is lower than the atmospheric pressure.

• If a ballmill suddenly stops while running, the first step is to check the power supply and circuit breaker.

• Oth...read more

Preventive maintenance is a proactive approach to maintenance that involves regular inspections and repairs to prevent equipment failure.

• Preventive maintenance involves scheduled inspections and repairs to prevent equipment failure

• It is a proactive approach to maintenance that reduces downtime and extends equipment life

• Examples include changing oil and filters, cleaning equipment, and replacing worn parts

• Preventive maintenance can be time-based or condition-based

• Time-based ma...read more

Yes, I have experience in boiler passing. It involves a thorough inspection of the boiler to ensure its safe and efficient operation.

• Boiler passing involves a visual inspection of the boiler's exterior and interior components.

• The inspection includes checking for leaks, cracks, corrosion, and other signs of wear and tear.

• The boiler's safety controls, valves, and gauges are also checked to ensure they are functioning properly.

• If any issues are found, repairs or replacements may...read more

The grade of materials used in storage tanks depends on the type of fluid being stored and the tank's operating conditions.

• The material should be compatible with the stored fluid to prevent corrosion or contamination.

• Common materials used for storage tanks include carbon steel, stainless steel, and aluminum.

• The thickness of the material should be sufficient to withstand the pressure and temperature of the stored fluid.

• The material should also be resistant to environmental fac...read more

To diagnose wiring and electrical faults, a maintenance engineer can follow these steps:

• Start by visually inspecting the wiring and electrical components for any visible damage or loose connections.

• Use a multimeter to test the continuity of wires and check for voltage drops or fluctuations.

• Perform insulation resistance tests to identify any insulation breakdown or leakage.

• Utilize circuit testers or voltage detectors to determine if power is reaching the intended destinations....read more

Questions related to maintenance engineering including eddy current, 5S TPM, electromagnetic induction, RPM measurement, DC motor, shift handover, major breakdown, and star delta starter.

• Eddy current is a current induced in a conductor due to a changing magnetic field

• 5S TPM is a methodology for workplace organization and standardization

• Electromagnetic induction is the production of an electromotive force across a conductor due to a changing magnetic field

• RPM measurement can b...read more

When encountering technical issues, it is important to follow a systematic approach to identify, troubleshoot, and resolve the problem.

• Start by gathering information about the issue, such as error messages, symptoms, and any recent changes or events that may have triggered the problem.

• Analyze the available data to narrow down the possible causes of the issue.

• Use diagnostic tools and techniques to further investigate and isolate the root cause.

• Develop a plan of action to addre...read more

A vapour compression cycle is a process used in refrigeration systems to remove heat from a space.

• The cycle consists of four main components: a compressor, a condenser, an expansion valve, and an evaporator.

• The compressor takes in low-pressure refrigerant gas and compresses it to high pressure.

• The high-pressure gas then flows to the condenser, where it releases heat and condenses into a high-pressure liquid.

• The liquid then flows through the expansion valve, where it undergoes...read more

The types of modules used with PLC include input modules, output modules, communication modules, analog modules, and specialty modules.

• Input modules are used to receive signals from sensors and other devices.

• Output modules are used to send signals to actuators and other devices.

• Communication modules enable PLCs to communicate with other devices or systems.

• Analog modules are used to process and control analog signals.

• Specialty modules are designed for specific functions, such ...read more

I chose the maintenance line because I enjoy problem-solving and working with my hands.

• I have always been interested in fixing things and finding solutions to technical problems.

• I enjoy the satisfaction of seeing a machine or system running smoothly after I have repaired or maintained it.

• Maintenance work allows me to constantly learn and stay updated with new technologies and equipment.

• I am detail-oriented and enjoy the process of troubleshooting and diagnosing issues.

• I have ...read more

I have a strong understanding of hydraulic equipment and their functions.

• I have experience in maintaining and repairing hydraulic pumps, valves, and cylinders.

• I am familiar with the different types of hydraulic systems and their applications.

• I have knowledge of hydraulic fluid properties and their effects on equipment performance.

• I am skilled in troubleshooting hydraulic equipment issues and finding solutions.

• I stay up-to-date with industry advancements and new technologies i...read more

Basic mechanical work in wind turbines includes maintenance, troubleshooting, and repair of components such as blades, gearbox, and generator.

• Inspecting and repairing wind turbine blades for damage or wear

• Performing regular maintenance on gearbox and generator

• Troubleshooting and repairing electrical and mechanical issues

• Replacing faulty components like bearings, gears, or sensors

• Performing alignment and balancing of rotating parts

• Ensuring proper lubrication of moving parts

• Mon...read more

A P-V diagram of a double stage air compressor shows the pressure-volume relationship during compression.

• The diagram consists of two stages of compression.

• The first stage compresses the air from atmospheric pressure to an intermediate pressure.

• The second stage compresses the air from the intermediate pressure to the final pressure.

• The volume decreases as the pressure increases during compression.

• The diagram can be used to analyze the efficiency and performance of the compress...read more

Maintenance activities involve the regular inspection, repair, and upkeep of equipment and facilities to ensure their optimal functioning.

• Maintenance activities include preventive maintenance, corrective maintenance, and predictive maintenance.

• Preventive maintenance involves scheduled inspections and maintenance tasks to prevent equipment breakdowns.

• Corrective maintenance involves repairing equipment after a breakdown or failure.

• Predictive maintenance uses data analysis and m...read more

Answering questions related to Maintenance Engineer interview.

• Types of boilers include fire tube, water tube, and electric boilers.

• Chilling plant capacity can be calculated by multiplying the flow rate by the temperature difference.

• Colour coding in industry is used to identify pipes, wires, and equipment based on their function or contents.

• Schedule maintenance is planned maintenance that is performed at regular intervals, while preventive maintenance is maintenance that is pe...read more

Bearings are used to reduce friction between two moving parts. There are different types of bearings.

• Plain bearings

• Rolling element bearings

• Jewel bearings

• Fluid bearings

• Magnetic bearings

Yes, I am familiar with Digital Multimeter. It is used to measure voltage, current, and resistance in electronic components.

• Set the multimeter to the appropriate setting for the component you are testing (voltage, current, or resistance)

• Connect the red probe to the positive terminal and the black probe to the negative terminal of the component

• Read the measurement displayed on the multimeter screen

• For HV diode: Set the multimeter to diode testing mode, place the red probe on t...read more

There are mainly two types of motors used in elevators: AC and DC motors.

• AC motors are commonly used in high-rise buildings and have a longer lifespan.

• DC motors are used in low-rise buildings and are more energy-efficient.

• AC motors are more expensive than DC motors.

• AC motors have a higher starting torque than DC motors.

• Examples of AC motors used in elevators include induction motors and synchronous motors.

• Examples of DC motors used in elevators include shunt-wound motors and ...read more

Parameters considered while building a boiler

• Boiler type and size

• Fuel type and availability

• Operating pressure and temperature

• Efficiency and emissions

• Safety features and regulations

• Maintenance requirements

• Cost and budget constraints

Draw three shafts with different diameters and specified length.

• Use a ruler and a compass to draw the shafts accurately.

• Label each shaft with its diameter and length.

• Ensure that the shafts are proportional to each other.

• Consider the material and application of the shafts when selecting diameters.

• Check the shafts for any defects or imperfections before use.

Calculating cooling tower TR, boiler efficiency, and types and capacity of chilling plant compressors.

• Cooling tower TR can be calculated using the formula: TR = (500 x GPM x Delta T)/12000

• Boiler efficiency can be calculated using the formula: Efficiency = (Output/Input) x 100

• Types of compressors include reciprocating, rotary screw, centrifugal, and scroll.

• Capacity of compressors is measured in tons of refrigeration (TR) or in cubic feet per minute (CFM).

• Chilling plant compres...read more

A load cell is a transducer that converts force into an electrical signal. Calibration involves applying known loads and adjusting the output signal.

• Load cell measures force or weight

• It converts the force into an electrical signal

• Calibration involves applying known loads and adjusting the output signal

• Calibration can be done using a calibration machine or weights

• Calibration should be done regularly to ensure accurate readings

SS 304 and SS 316 are both stainless steel alloys, but they differ in their composition and properties.

• SS 304 contains 18% chromium and 8% nickel, while SS 316 contains 16% chromium, 10% nickel, and 2% molybdenum.

• SS 316 has better corrosion resistance than SS 304, especially in environments with chlorides or acids.

• SS 316 is more suitable for marine applications or those involving exposure to harsh chemicals.

• SS 304 is generally more affordable and widely used in applications w...read more

A three-axis robot is a robotic system that operates in three dimensions, allowing it to move and manipulate objects in a wide range of directions.

• A three-axis robot typically consists of three linear axes, each capable of independent movement along a specific axis (X, Y, and Z).

• The X-axis controls horizontal movement, the Y-axis controls vertical movement, and the Z-axis controls depth or forward/backward movement.

• By combining movements along these three axes, the robot can ...read more

Power factor is the ratio of real power to apparent power in an electrical system. It needs to be maintained for efficient power transfer and to avoid penalties from utility companies.

• Power factor impacts the efficiency of power transfer in electrical systems

• Low power factor can result in higher energy costs and penalties from utility companies

• It affects the quality of power supply and can lead to voltage drops and equipment overheating

• Power factor can be improved by using po...read more

Preventive maintenance in automation industry involves regular inspections, cleaning, lubrication, and replacement of parts.

• Regularly inspecting equipment to identify potential issues before they become major problems

• Cleaning and lubricating machinery to prevent wear and tear

• Replacing worn or damaged parts before they fail

• Using predictive maintenance techniques such as vibration analysis and thermography to detect potential problems

• Creating a maintenance schedule and sticking...read more

Elevator is a vertical transportation device that moves people or goods between floors of a building.

• Elevators are powered by electric motors that drive traction cables or hydraulic pistons.

• They have safety features such as emergency brakes, overspeed governors, and door interlocks.

• Elevators can be controlled by various systems such as relay logic, microprocessors, or destination dispatch.

• Modern elevators also have features such as touchscreens, voice announcements, and desti...read more

AC drives control the speed of AC motors by varying the frequency of the electrical supply.

• AC drives use power electronics to convert AC power to DC power and then back to AC power at the desired frequency.

• Different types of starters include direct-on-line (DOL), star-delta, soft starters, and variable frequency drives (VFDs).

• DOL starters provide full voltage to the motor, while star-delta starters reduce the voltage during starting to reduce current and torque.

• Soft starters ...read more

Blowdown of cooling tower can be calculated using cycles of concentration. Maintenance practices include regular cleaning, inspection, and water treatment. Cooling tower capacity can be calculated based on heat load and design parameters.

• Calculate blowdown using cycles of concentration formula: Blowdown = Evaporation Loss / (Cycles of Concentration - 1)

• Maintenance practices include regular cleaning of cooling tower fill, drift eliminators, and basin, inspection of mechanical ...read more

Proximity sensors are devices that detect the presence or absence of an object using electromagnetic fields, light, or sound.

• Proximity sensors can be categorized into inductive, capacitive, ultrasonic, and photoelectric sensors.

• Inductive sensors detect metal objects using electromagnetic fields.

• Capacitive sensors detect non-metal objects by measuring changes in capacitance.

• Ultrasonic sensors use sound waves to detect objects within a certain range.

• Photoelectric sensors use li...read more

There are different types of hydraulic oils used in hydraulic machines depending on the application and operating conditions.

• Mineral-based hydraulic oil is the most common type used in hydraulic machines.

• Synthetic hydraulic oil is used in high-performance applications where extreme temperatures and pressures are encountered.

• Biodegradable hydraulic oil is used in environmentally sensitive areas.

• Fire-resistant hydraulic oil is used in applications where there is a risk of fire....read more