50+ Maintenance Engineer Interview Questions and Answers for Freshers

The most difficult electrical installation I completed was rewiring an entire industrial facility.

• Rewiring an entire industrial facility required extensive planning and coordination.

• I had to carefully map out the existing electrical system and create a detailed plan for the new wiring.

• The installation involved working with high voltage equipment and ensuring safety measures were followed.

• I had to troubleshoot and resolve complex electrical issues during the installation proce...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

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

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

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

A type of mechanical seal is the cartridge seal which consists of a rotating and stationary face.

• Cartridge seals are pre-assembled units that can be easily installed

• They are commonly used in pumps and mixers

• The rotating face is attached to the shaft while the stationary face is mounted in the seal housing

• The seal faces are held together by a spring or other device to maintain contact and prevent leakage

Flow in a pipe is the movement of fluid through the pipe. It can be calculated using the formula Q = A * V, where Q is the flow rate, A is the cross-sectional area of the pipe, and V is the velocity of the fluid.

• Flow in a pipe refers to the volume of fluid passing through the pipe per unit time.

• To calculate flow in a given size of pipe, you can use the formula Q = A * V, where Q is the flow rate, A is the cross-sectional area of the pipe, and V is the velocity of the fluid.

• Th...read more

Mentonus is a software used for maintenance management.

• Mentonus is a computerized maintenance management system (CMMS) that helps in organizing and tracking maintenance activities.

• It allows for efficient scheduling of preventive maintenance tasks.

• Mentonus can generate work orders, track inventory, and manage equipment maintenance history.

• It provides real-time data and analytics to optimize maintenance processes.

• With Mentonus, maintenance engineers can prioritize tasks, reduce...read more

MS and SS refer to different types of materials used in the construction of equipment such as pumps, gearboxes, reactors, and boilers.

• MS stands for Mild Steel and is a type of carbon steel that is commonly used in industrial applications.

• SS stands for Stainless Steel and is a corrosion-resistant alloy that is often used in applications where hygiene and cleanliness are important.

• The choice of material depends on the specific application and the properties required for the equ...read more

Colour coding on three phase supply RYB is used for easy identification and proper connection of phases.

• Colour coding helps in identifying different phases easily

• Prevents incorrect connections which can lead to equipment damage or accidents

• Standardizes the wiring system for consistency and safety

• Red phase (R), Yellow phase (Y), Blue phase (B) are commonly used for RYB colour coding

This question covers properties of air, generation of CO2 gas, and its applications.

• Air is a mixture of gases, primarily nitrogen and oxygen

• CO2 gas is generated through combustion of fossil fuels, fermentation, and respiration

• CO2 gas is used in fire extinguishers, carbonation of beverages, and as a refrigerant

I have worked on machines with various geometries, including cylindrical, rectangular, and spherical shapes.

• Worked on machines with cylindrical geometry, such as lathes and milling machines.

• Handled machines with rectangular geometry, like conveyor belts and packaging equipment.

• Dealt with machines with spherical geometry, such as ball bearings and rotary valves.

A CNC machine can have 3, 4, or 5 axes depending on its configuration.

• The X, Y, and Z axes are common in 3-axis machines.

• 4-axis machines add a rotary axis, usually the A-axis.

• 5-axis machines add a second rotary axis, usually the B-axis.

• Some machines may have additional axes for specialized operations, such as milling machines with a tilting spindle head.

• The number of axes determines the machine's capabilities and the complexity of its programming.

Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied across it, given a constant resistance.

• Ohm's Law: V = I * R (Voltage = Current * Resistance)

• Current is directly proportional to Voltage when Resistance is constant

• Higher voltage leads to higher current flow, and vice versa

• Lower resistance leads to higher current flow, and vice versa

• Example: If a circuit has a voltage of 12V and a resistance of 4 ohms, the current flow...read more

My current CTC is $60,000 and I am looking for a 10% increment.

• My current CTC is $60,000

• I am seeking a 10% increment

• This would bring my desired CTC to $66,000

A battery converts chemical energy into electrical energy. For example, a lead-acid battery used in cars.

• Batteries work by converting chemical energy into electrical energy

• Common types of batteries include lead-acid, alkaline, lithium-ion, and nickel-cadmium

• Lead-acid batteries are commonly used in cars and work by converting lead and lead oxide into lead sulfate

• Alkaline batteries use zinc and manganese dioxide to create a chemical reaction

• Lithium-ion batteries are commonly us...read more

Oil lubricant is used in elevators to reduce friction and wear on moving parts.

• Oil lubricant reduces friction between moving parts in elevators.

• It helps to prevent wear and tear on elevator components.

• Oil lubricant also helps to dissipate heat generated by friction.

• Different types of oil lubricants are used depending on the elevator's design and usage.

• Regular maintenance and oil changes are necessary to ensure proper elevator function.

The latest motor used in elevators is the permanent magnet synchronous motor (PMSM).

• PMSM is more energy-efficient and has a higher power density than traditional motors.

• It uses rare-earth magnets to create a magnetic field that rotates the motor shaft.

• PMSM is also quieter and requires less maintenance than other motors.

• Examples of elevators that use PMSM include Otis Gen2 and KONE MonoSpace 500.

Maintenance procedure involves regular inspection, cleaning, repair and replacement of equipment to ensure optimal performance and prevent breakdowns.

• Create a maintenance schedule based on manufacturer recommendations and equipment usage

• Perform regular inspections to identify potential issues before they become major problems

• Clean and lubricate equipment as needed to prevent wear and tear

• Repair or replace damaged or worn parts promptly to prevent further damage

• Document all ma...read more

My areas of interest include electrical systems, mechanical systems, and preventive maintenance.

• Electrical systems: I have a strong interest in troubleshooting and repairing electrical systems, such as motors, control panels, and wiring.

• Mechanical systems: I enjoy working with mechanical components, such as pumps, valves, and conveyors. I have experience in maintaining and repairing these systems.

• Preventive maintenance: I believe in the importance of regular inspections and m...read more

The modes of heat transfer are conduction, convection, and radiation.

• Conduction: Heat transfer through direct contact between particles. Example: Touching a hot pan.

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

• Radiation: Heat transfer through electromagnetic waves. Example: Feeling the warmth of the sun.

Breakdown is an unexpected failure of equipment or machinery. KPI stands for Key Performance Indicator, a measurable value that indicates how well a company is achieving its goals.

• Breakdown can cause production delays and loss of revenue

• KPIs can be used to track maintenance performance and identify areas for improvement

• Examples of KPIs for maintenance include equipment uptime, mean time between failures, and maintenance cost per unit produced

Star Delta Starter Diagram is a method used to reduce the starting current of induction motors.

• Consists of three contactors - one for star connection and two for delta connection

• Switches from star to delta configuration after motor reaches a certain speed

• Reduces starting current by starting in star configuration and then switching to delta

Types of maintenance include preventive, predictive, corrective, and proactive maintenance. Each type requires different strategies to effectively manage and address maintenance issues.

• Preventive maintenance involves regularly scheduled inspections and tasks to prevent breakdowns (e.g. changing air filters in HVAC systems)

• Predictive maintenance uses data and analytics to predict when equipment will fail and schedule maintenance accordingly (e.g. vibration analysis to detect b...read more

Types of maintenance include corrective, preventive, predictive, and proactive maintenance.

• Corrective maintenance involves fixing a problem after it has occurred.

• Preventive maintenance involves regularly scheduled maintenance to prevent problems from occurring.

• Predictive maintenance involves using data and analytics to predict when maintenance is needed.

• Proactive maintenance involves identifying and addressing potential issues before they become problems.

• Examples include repl...read more

Machines need regular preventive maintenance (PM) to ensure optimal performance and longevity.

• Regular cleaning and lubrication

• Inspection and replacement of worn parts

• Calibration and adjustment of sensors and controls

• Testing and monitoring of performance

• Documentation of maintenance activities

• Training of operators and maintenance staff

The second law of thermodynamics states that the total entropy of a closed system will always increase over time. The third law states that it is impossible to reach absolute zero temperature.

• 2nd law: entropy always increases in a closed system

• 3rd law: absolute zero temperature is impossible to reach

• 2nd law explains why perpetual motion machines are impossible

• 3rd law is used to calculate the entropy of a substance at absolute zero

• Both laws are fundamental to understanding ene...read more

Water hammering is a phenomenon where pipes make loud banging noises due to sudden changes in water flow velocity.

• Water hammering occurs when a valve is suddenly closed, causing a pressure surge in the pipes.

• The pressure surge creates a shockwave that travels through the pipes, resulting in loud banging noises.

• Water hammering can lead to damage to pipes, fittings, and appliances if not addressed.

• To prevent water hammering, install water hammer arrestors or pressure-reducing v...read more

Synchronous motors are used to maintain constant speed and power supply in industrial applications.

• Synchronous motors have a rotor with permanent magnets that rotate at the same speed as the stator's magnetic field.

• They are used in applications where constant speed is required, such as in electric power generation, industrial machinery, and robotics.

• Synchronous motors are also used in applications where precise control of speed and torque is necessary, such as in electric veh...read more

A cooling tower is a heat rejection device that removes waste heat from a process system.

• Cooling towers are used in HVAC systems, power plants, and other industrial settings.

• They work by evaporating water to remove heat from the system.

• Parts of a cooling tower include the basin, fill, drift eliminators, fans, and pumps.

• Regular maintenance is important to prevent scaling, corrosion, and other issues.

• Cooling towers can also be equipped with water treatment systems to improve ef...read more

Motor full load current can be calculated using the formula: FLA = (P x 746) / (V x Eff x PF x 1.73)

• Calculate the power (P) of the motor in horsepower

• Determine the voltage (V) of the motor

• Find the efficiency (Eff) of the motor

• Identify the power factor (PF) of the motor

• Use the formula FLA = (P x 746) / (V x Eff x PF x 1.73) to calculate the full load current

An ammeter is a device used to measure electric current flowing through a circuit.

• Ammeters are connected in series with the circuit in which the current is to be measured.

• They have a low resistance to prevent significant voltage drop in the circuit.

• Ammeters are calibrated in units of amperes (A) or milliamperes (mA).

• They typically have a needle or digital display to indicate the current reading.

• Ammeters can be analog or digital depending on the design.

MTTR stands for Mean Time To Repair and MTBF stands for Mean Time Between Failures.

• MTTR is the average time taken to repair a failed system or equipment.

• MTBF is the average time between two consecutive failures of a system or equipment.

• MTTR is used to measure the efficiency of maintenance and repair processes.

• MTBF is used to measure the reliability of a system or equipment.

• MTBF = (total operating time - total downtime) / number of failures

• MTTR = total downtime / number of fai...read more

Traction is the force applied to an object in a direction opposite to its movement.

• Traction is used in various fields such as engineering, physics, and medicine.

• In engineering, traction is used to describe the force applied to move a vehicle or machine.

• In physics, traction is used to describe the force applied to an object to prevent it from moving.

• In medicine, traction is used to describe the pulling force applied to a body part to align or immobilize it.

• Examples of traction...read more

MCB stands for Miniature Circuit Breaker. It is an electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.

• MCB automatically switches off the electrical circuit during abnormal conditions like overload or short circuit.

• It can be easily reset after tripping by manually turning it back on.

• MCBs are commonly used in residential, commercial, and industrial electrical installations.

• They come in different current ratings to suit va...read more

MTTR is the average time to repair a failed system while MTBF is the average time between failures.

• MTTR measures the maintainability of a system while MTBF measures its reliability.

• MTTR is calculated by dividing the total downtime by the number of failures while MTBF is calculated by dividing the total uptime by the number of failures.

• MTTR is usually shorter than MTBF as it only measures the time to repair a failed system while MTBF measures the time between failures.

• MTTR is ...read more

Pitch circular dia refers to the diameter of the pitch circle in a gear system.

• Pitch circular dia is the imaginary circle that passes through the center of the gear teeth.

• It is used to determine the size and spacing of the gear teeth.

• The pitch circular dia is calculated using the number of teeth and the module or diametral pitch of the gear.

• For example, in a gear system with a module of 2 and 20 teeth, the pitch circular dia would be 40mm.

Maintenance work includes preventive, corrective, and predictive maintenance to ensure optimal performance of equipment and facilities.

• Preventive maintenance involves routine inspections, cleaning, and replacement of parts to prevent breakdowns and extend equipment life.

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

• Predictive maintenance involves using data and analytics to predict when maintenance is needed before a breakdown occurs.

• Mai...read more

Types of motors include AC motors, DC motors, synchronous motors, asynchronous motors, and stepper motors.

• AC motors: Alternating current motors commonly used in household appliances and industrial applications.

• DC motors: Direct current motors used in applications where speed control is important, such as in robotics.

• Synchronous motors: Motors that rotate at a fixed speed determined by the frequency of the applied voltage.

• Asynchronous motors: Motors that rotate at a speed slig...read more

The maximum operation temperature of bearings depends on the type of bearing and the lubricant used.

• The maximum operation temperature for standard bearings is usually around 120-150°C

• High-temperature bearings can operate at temperatures up to 350°C

• The type of lubricant used can also affect the maximum operation temperature

• Exceeding the maximum operation temperature can cause the bearing to fail prematurely

A module is a self-contained unit of software that performs a specific function and can be used independently or as part of a larger system.

• A module is a component or part of a software system that can be developed, tested, and maintained separately.

• It encapsulates a set of related functions or features that can be reused in different parts of a program.

• Modules promote code reusability, modularity, and maintainability.

• They can be written in different programming languages and...read more

There are several types of joints in engineering, including welded joints, bolted joints, riveted joints, and adhesive joints.

• Welded joints

• Bolted joints

• Riveted joints

• Adhesive joints

LMTD stands for Log Mean Temperature Difference and is used in heat exchanger design to calculate the average temperature difference between the hot and cold fluids.

• LMTD is used in the design of heat exchangers to determine the overall heat transfer coefficient.

• It takes into account the temperature difference between the hot and cold fluids at different points along the heat exchanger.

• The formula for LMTD is (ΔT1 - ΔT2) / ln(ΔT1 / ΔT2), where ΔT1 and ΔT2 are the temperature d...read more

Reynolds number is a dimensionless quantity used to predict fluid flow patterns and turbulence.

• It is used to determine whether a fluid flow is laminar or turbulent

• It is calculated using the fluid velocity, density, viscosity, and characteristic length

• Higher Reynolds number indicates turbulent flow while lower indicates laminar flow

• It is named after Osborne Reynolds, a British physicist who first described it in 1883

The question is incomplete or incorrect. There is no such term as 'back las'.

• There is no known term or phrase as 'back las'.

• It is possible that the interviewer made a mistake or was trying to ask a different question.

• As a maintenance engineer, it is important to clarify any unclear or confusing questions to ensure accurate responses.

MS Office is a suite of productivity software used for various tasks such as creating documents, spreadsheets, and presentations.

• MS Word is used for creating and editing documents

• MS Excel is used for creating and managing spreadsheets

• MS PowerPoint is used for creating presentations

• MS Outlook is used for managing emails and calendars

• MS Access is used for creating and managing databases

A motor converts electrical energy into mechanical energy to produce motion, while an alternator converts mechanical energy into electrical energy.

• Motor is used to provide motion, while alternator is used to generate electricity

• Motor consumes electrical energy, while alternator produces electrical energy

• Examples: Electric fan motor, car alternator