500+ Maintenance Engineer Interview Questions and Answers

Gate valves and ball valves are two common types of valves used in industrial applications.

• Gate valves have a sliding gate that controls the flow of fluid through the valve.

• Ball valves have a rotating ball with a hole in the middle that controls the flow of fluid through the valve.

• Gate valves are typically used for on/off control of fluid flow, while ball valves are used for throttling and control applications.

• Gate valves are often larger and heavier than ball valves, and req...read more

A diode is an electronic component that allows current to flow in one direction only.

• A diode has two terminals: an anode and a cathode.

• To check if a diode is true or false, set the multimeter to the diode test mode.

• Connect the red probe to the anode and the black probe to the cathode.

• If the diode is good, the multimeter will show a voltage drop of around 0.6 to 0.7 volts.

• If the diode is bad, the multimeter will show no voltage drop or a very high voltage drop.

• Reverse the prob...read more

The glass thickness of msgl reactor varies depending on the manufacturer and model.

• The glass thickness can range from 5mm to 20mm.

• It is important to consult the manufacturer's specifications for the specific reactor in question.

• Factors such as pressure and temperature can also affect the required glass thickness.

• Regular inspections and maintenance should be conducted to ensure the integrity of the glass lining.

Calibration of I/P converter involves adjusting the output pressure to match the input signal.

• Connect the I/P converter to a pressure source and a signal generator

• Adjust the input signal to the desired value

• Measure the output pressure and adjust it to match the input signal

• Repeat the process at different input signal levels to ensure accuracy

• Document the calibration results for future reference

Soda Ash related equipment includes conveyors, crushers, screens, and calciners used in the production of sodium carbonate.

• Conveyors are used to transport raw materials and finished products.

• Crushers are used to break down large chunks of soda ash into smaller pieces.

• Screens are used to separate different sizes of soda ash particles.

• Calciners are used to heat and convert sodium bicarbonate into sodium carbonate.

• Examples of soda ash related equipment include belt conveyors, sc...read more

Maintenance has several benefits including increased equipment lifespan, improved safety, reduced downtime, and cost savings.

• Increased equipment lifespan: Regular maintenance helps identify and address issues before they become major problems, extending the lifespan of equipment.

• Improved safety: Maintenance ensures that equipment is functioning properly, reducing the risk of accidents and injuries.

• Reduced downtime: Regular maintenance minimizes unexpected breakdowns and repai...read more

DC supply can be converted into AC supply using an inverter.

• Inverter is an electronic device that converts DC to AC.

• It uses a switching circuit to alternate the polarity of DC voltage.

• The output waveform can be modified using filters and transformers.

• Examples of inverters include square wave, modified sine wave, and pure sine wave inverters.

Use a phase failure relay to protect the motor.

• Install a phase failure relay to detect the absence of a phase and disconnect the motor from the supply.

• Check the motor's wiring and connections to ensure they are correct and secure.

• If the motor is already running, shut it down immediately to prevent damage.

• Consult with an electrician to determine the cause of the phase failure and resolve the issue.

• Consider using a backup power source or generator to prevent future phase failur...read more

Experience in a company's category and efficient knowledge are equally important for a maintenance engineer.

• Experience in the same industry as the company can help in understanding the specific maintenance needs.

• Efficient knowledge of maintenance techniques and equipment is crucial for effective maintenance.

• Experience in implementing preventive maintenance programs can help reduce downtime and increase equipment lifespan.

Robots use sensors and algorithms to memorize their origin and moving positions.

• Robots use sensors such as encoders, accelerometers, and gyroscopes to determine their position and orientation.

• Algorithms such as SLAM (Simultaneous Localization and Mapping) are used to create a map of the robot's environment and track its movements.

• Once the robot has determined its origin position, it can use relative positioning to move to other positions.

• Some robots also use markers or beacon...read more

Different types of gears include spur gears, helical gears, bevel gears, worm gears, and rack and pinion gears.

• Spur gears have straight teeth and are the simplest and most common type of gear.

• Helical gears have angled teeth and provide smoother and quieter operation compared to spur gears.

• Bevel gears have cone-shaped teeth and are used to transmit power between intersecting shafts.

• Worm gears consist of a worm and a worm wheel and are used for high reduction ratios and self-lo...read more

In house wiring, we use alternating current (AC) power.

• AC power is used in most homes and buildings for lighting, appliances, and other electrical needs.

• The voltage used in house wiring is typically 120 or 240 volts, depending on the country and region.

• Wiring is typically done with copper or aluminum conductors, and is protected by circuit breakers or fuses.

• Grounding is an important safety feature in house wiring, providing a path for excess current to flow to the earth.

• Diffe...read more

BT40 and BT50 are terms used in the field of machining and refer to the type of tool holder used in CNC machines.

• BT40 and BT50 are standardized tool holder systems used in CNC machining.

• They are named after the taper size of the tool holder, which determines the compatibility with the machine spindle.

• BT40 has a taper size of 40 and BT50 has a taper size of 50.

• The tool holders are used to securely hold cutting tools in the machine spindle.

• Different tool holders are required fo...read more

A diode is an electronic component that allows current to flow in only one direction. To check if it's ok, use a multimeter in diode mode.

• A diode has two terminals: an anode and a cathode

• When forward-biased, a diode allows current to flow through it

• When reverse-biased, a diode blocks current flow

• To check if a diode is ok, use a multimeter in diode mode and measure the voltage drop across the diode

• A good diode will have a voltage drop of around 0.6-0.7V

Yes, I have knowledge and experience in welding, grinding, and cutting.

• I have completed a welding course and have experience in MIG, TIG, and stick welding.

• I am proficient in using various cutting tools such as plasma cutters, saws, and torches.

• I have experience in grinding and polishing metal surfaces to a smooth finish.

• I am familiar with safety procedures and protocols when working with these tools.

The principle of a motor is the conversion of electrical energy into mechanical energy.

• Motors work based on the principle of electromagnetic induction.

• When an electric current flows through a wire in the presence of a magnetic field, a force is exerted on the wire, causing it to move.

• This movement is used to generate mechanical energy, which can be used to perform work.

• Motors can be found in various applications such as electric vehicles, industrial machinery, and household a...read more

The main problem in CNC machines is tool wear and breakage.

• Tool wear and breakage can lead to poor quality of machined parts.

• It can also cause machine downtime and increased maintenance costs.

• Regular monitoring and replacement of tools is necessary to prevent these issues.

• Improper tool selection or incorrect machining parameters can contribute to tool wear and breakage.

• Examples of tool wear include flank wear, crater wear, and chipping.

Gearbox overhauling involves disassembling, inspecting, repairing, and reassembling the gearbox to ensure optimal performance.

• Start by draining the gearbox oil and removing the gearbox from the equipment.

• Disassemble the gearbox carefully, noting the position of each component for reassembly.

• Inspect all parts for wear, damage, or signs of malfunction.

• Replace any worn or damaged parts with new ones.

• Clean all components thoroughly before reassembly.

• Reassemble the gearbox followi...read more

Pipe size for given pressure of steam can be calculated using the formula for flow rate and velocity.

• Calculate the required flow rate of steam based on the application and process requirements.

• Determine the velocity of steam based on the flow rate and pipe size.

• Use the Darcy-Weisbach equation or other relevant formulas to calculate the pressure drop in the pipe.

• Select a pipe size that can handle the required flow rate and pressure drop without exceeding the maximum allowable ...read more

Working with a fire engine under high pressure requires proper training and knowledge of the equipment.

• Ensure proper training on operating the fire engine with high pressure

• Understand the different components and controls of the fire engine

• Follow safety protocols and guidelines

• Maintain and inspect the fire engine regularly

• Practice efficient water management to maximize effectiveness

• Be aware of potential hazards and take necessary precautions

• Coordinate with other team members ...read more

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

PT, LT and LVDT are types of sensors used in engineering for measuring pressure, temperature and displacement respectively.

• PT stands for Pressure Transducer and is used to measure pressure in various applications such as hydraulic systems, engines, and pipelines.

• LT stands for Linear Transducer and is used to measure temperature in various applications such as engines, HVAC systems, and industrial processes.

• LVDT stands for Linear Variable Differential Transformer and is used t...read more

To check a motor, perform visual inspection, check for unusual noises or vibrations, test electrical connections, measure voltage and current, and perform insulation resistance test.

• Perform visual inspection for any signs of damage or wear

• Check for unusual noises or vibrations during operation

• Test electrical connections for tightness and proper wiring

• Measure voltage and current to ensure they are within specifications

• Perform insulation resistance test to check for any insulat...read more

7QC tools are quality control tools used to identify and solve quality-related issues. MTTR stands for Mean Time To Repair, MTBF stands for Mean Time Between Failures.

• 7QC tools include Pareto analysis, cause-and-effect diagram, scatter diagram, etc.

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

• MTBF is the average time between failures of a component or system.

• Types of breakdowns can include mechanical, electrical, software, etc.

• Types of failures can in...read more

VFD stands for Variable Frequency Drive, it is used to control the speed of an electric motor.

• VFD is used to vary the speed of an electric motor by adjusting the frequency of the electrical supply to the motor.

• Basic control for operating a VFD includes setting the desired speed or frequency, start/stop commands, and monitoring parameters like current and voltage.

• Examples of basic controls for operating a VFD include keypad control, remote control via a PLC, and communication ...read more

The efficiency of a turbine is less due to various factors such as friction, heat losses, and mechanical losses.

• Friction between the moving parts of the turbine reduces its efficiency.

• Heat losses occur due to the conversion of thermal energy into mechanical energy.

• Mechanical losses include losses in bearings, seals, and other components.

• Efficiency equation: Efficiency = (Useful output energy / Input energy) * 100%

Answering questions related to difficult maintenance activities and troubleshooting DE system issues.

• Performed difficult maintenance activities such as replacing a faulty gearbox in a wind turbine

• To physically find out if DE system is jammed, I would inspect the system for any blockages or obstructions

• If the bag on DE system is torn, I would conduct a visual inspection and check for any leaks or tears in the bag

To check machine backlash in a CNC machine, perform a backlash test by moving the machine's axis in both directions and measuring the difference in position.

• Perform a backlash test by moving the machine's axis in one direction and measuring the position

• Then move the axis in the opposite direction and measure the position again

• Calculate the difference in position to determine the backlash

• Repeat the test for each axis of the CNC machine

• Adjust the machine's backlash compensation...read more

Life of equipment refers to the duration of time that the equipment can function effectively and efficiently.

• The life of equipment is determined by various factors such as usage, maintenance, and environmental conditions.

• Regular maintenance and timely repairs can extend the life of equipment.

• Equipment manufacturers provide an estimated lifespan for their products, but this can vary depending on usage and maintenance.

• Factors such as wear and tear, corrosion, and obsolescence c...read more

A pump is a mechanical device used to move fluids from one place to another. There are various types of pumps.

• Pumps are used in various industries such as oil and gas, water treatment, and manufacturing.

• Types of pumps include centrifugal pumps, reciprocating pumps, and rotary pumps.

• Centrifugal pumps are commonly used for low viscosity fluids, while reciprocating pumps are suitable for high-pressure applications.

• Examples of pumps include water pumps, fuel pumps, and air compre...read more

VFD output voltage increases after rectification due to the conversion process from AC to DC, typically around 1.4 times the input voltage.

• VFDs convert AC power to DC power through rectification

• The output voltage of a VFD is typically around 1.4 times the input voltage

• This increase in voltage is necessary for the VFD to effectively control the speed of the motor

PM stands for Preventive Maintenance, Breakdown Maintenance is fixing equipment after it fails, Productive Maintenance is improving equipment to increase productivity.

• Preventive Maintenance (PM) involves regularly scheduled maintenance to prevent equipment failure.

• Breakdown Maintenance involves fixing equipment after it has failed.

• Productive Maintenance involves improving equipment to increase productivity and reduce downtime.

• Examples of PM include changing oil in a car or re...read more

2 phase and 3 phase are different types of electrical power distribution systems.

• 2 phase system has two conductors and produces a single alternating current waveform.

• 3 phase system has three conductors and produces three alternating current waveforms.

• 2 phase system is less common and used in older applications.

• 3 phase system is more efficient and widely used in industrial and commercial settings.

• 2 phase system requires a neutral wire, while 3 phase system does not.

• Examples of...read more

Heat treatment furnace is used to heat materials to high temperatures to alter their physical and chemical properties.

• Heat treatment furnace is used in metallurgy to harden metals by heating them to high temperatures and then cooling them rapidly.

• It is also used to anneal metals by heating them to a specific temperature and then cooling them slowly.

• Heat treatment furnace is used in the manufacturing of glass, ceramics, and other materials.

• It is important to maintain the tempe...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

Water in gearbox oil can be confirmed by conducting an oil analysis.

• Conduct an oil analysis to check for the presence of water in the gearbox oil.

• Check for any signs of water contamination such as a milky appearance or a foul odor.

• Inspect the oil filter for any signs of water contamination.

• Check the oil level and color regularly to detect any changes that may indicate water contamination.

• Perform regular maintenance on the gearbox to prevent water contamination.

Boilers are vessels that heat water or other fluids to generate steam or hot water for various applications.

• Boilers are used in industries, commercial buildings, and residential homes.

• They work by transferring heat from a fuel source to water or other fluids.

• The steam or hot water produced by boilers can be used for heating, power generation, or process applications.

• There are different types of boilers, including fire-tube boilers, water-tube boilers, and electric boilers.

• Fir...read more

Draw the electrical circuit to control barrel heater through SSR/contactor.

• Start by identifying the power source and the barrel heater.

• Connect the power source to the input terminals of the SSR/contactor.

• Connect the output terminals of the SSR/contactor to the barrel heater.

• Include appropriate fuses and circuit breakers for safety.

• Consider using a control signal (e.g., from a temperature controller) to trigger the SSR/contactor.

To calculate the capacitor for a single phase motor, you need to determine the motor's power factor and the desired level of power factor correction.

• Determine the power factor of the motor using a power factor meter or by calculating it using the motor's apparent power and true power.

• Decide on the desired level of power factor correction, typically between 0.9 and 1.0.

• Use the formula: Capacitance (in Farads) = (Apparent Power (in VA) x (1 - Desired Power Factor^2)) / (2 x π x...read more

SMPS is a power supply that uses high-frequency switching to convert AC voltage to DC voltage.

• SMPS is more efficient than traditional linear power supplies

• It uses a switching regulator to control the output voltage

• SMPS can be found in computers, TVs, and other electronic devices

• It can be designed to work with different input voltages and frequencies

Types of lagging, use of ZSS proxy, and process of belt joint are important for maintenance engineers.

• Types of lagging include ceramic, rubber, and polyurethane.

• ZSS proxy is used for remote monitoring and control of equipment.

• Process of belt joint involves preparing the belt ends, applying adhesive, and pressing the ends together.

Maintenance is the process of ensuring that equipment, machinery, or facilities are in good working condition.

• Regular inspection and repair of equipment

• Preventive maintenance to avoid breakdowns

• Corrective maintenance to fix issues

• Predictive maintenance to anticipate problems

• Maintenance scheduling and record-keeping

• Training and development of maintenance staff

• Continuous improvement of maintenance processes

• Examples: oil changes for cars, cleaning and servicing of HVAC systems, ...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

In my previous job, I was responsible for electrical maintenance of motor transformers and other machines.

• Performed regular maintenance and troubleshooting of motor transformers.

• Inspected and repaired electrical components and circuits.

• Conducted preventive maintenance to ensure optimal performance and minimize downtime.

• Collaborated with a team to diagnose and resolve electrical issues.

• Maintained accurate records of maintenance activities and equipment status.

• Implemented safet...read more

Check power source, power switch, fuse, and connections.

• Check if the power source is working and supplying electricity to the machine.

• Ensure the power switch is turned on.

• Inspect the fuse to see if it is blown and needs replacement.

• Check all connections and cables to ensure they are properly connected and not damaged.

• Test the machine with a different power source to rule out electrical issues.

Blow down in boilers is necessary to remove impurities and maintain water quality. The pH of water in the boiler should be monitored and adjusted using chemicals like sodium hydroxide or sulfuric acid.

• Blow down is done to remove impurities such as dissolved solids, suspended solids, and alkalinity from the boiler water.

• The pH of water in the boiler should be maintained within a specific range to prevent corrosion and scale formation.

• Chemicals like sodium hydroxide (NaOH) or s...read more

Relative humidity in OT is maintained through proper ventilation, air conditioning, and dehumidification.

• Proper ventilation helps to circulate air and prevent moisture buildup.

• Air conditioning helps to cool and dehumidify the air.

• Dehumidifiers can be used to remove excess moisture from the air.

• Regular maintenance of HVAC systems is important to ensure proper functioning.

• Monitoring and controlling humidity levels is crucial for preventing the growth of bacteria and fungi.

• Relat...read more