Praj Industries Commissioning Engineer Interview Questions and Answers

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

• MTTR measures downtime and repair time, while MTBF measures reliability and uptime.

• MTTR is a measure of how quickly a system can be restored after a failure, while MTBF is a measure of how long a system can operate without failing.

• MTTR is typically used to evaluate maintenance performance, while MTBF is used to evaluate ...read more

Pumps and boilers are essential equipment in various industries. Pumps are used to transfer fluids, while boilers generate steam.

• Pumps are devices that move fluids by mechanical action.

• There are different types of pumps, such as centrifugal pumps, reciprocating pumps, and rotary pumps.

• Centrifugal pumps are commonly used in water supply systems and HVAC applications.

• Reciprocating pumps are used in high-pressure applicat...read more

AHU stands for Air Handling Unit. It is a device used to regulate and circulate air as part of a heating, ventilation, and air conditioning (HVAC) system.

• AHU is responsible for conditioning and distributing air within a building.

• It consists of components like fans, filters, heating and cooling coils, dampers, and controls.

• The fans in AHU draw in outside air, filter it, and then distribute it to various areas of the bui...read more

There are several types of boilers used in various industries and applications.

• There are four main types of boilers: fire-tube, water-tube, electric, and biomass.

• Fire-tube boilers are commonly used in steam locomotives and industrial plants.

• Water-tube boilers are used in power stations and large industrial settings.

• Electric boilers are used for heating purposes in residential and commercial buildings.

• Biomass boilers us...read more

SF6 gas is used in circuit breakers due to its excellent electrical insulation properties and high dielectric strength.

• SF6 gas has high dielectric strength, making it an effective insulator in high voltage applications.

• It has excellent arc-quenching properties, allowing it to quickly extinguish electrical arcs.

• SF6 gas is chemically stable and non-toxic, making it safe for use in circuit breakers.

• It has a high thermal c...read more

Substations use various protections to ensure safety and reliability of power supply.

• Overcurrent protection

• Ground fault protection

• Transformer protection

• Surge protection

• Circuit breaker

• Relay protection

• Isolation switches

• Lightning arresters

• Fire protection

• Security measures

Designing a vacuum pump involves selecting the appropriate type, determining the required flow rate and pressure, and sizing the components.

• Choose the type of vacuum pump based on the application (e.g. rotary vane, diaphragm, scroll, etc.)

• Determine the required flow rate and pressure for the system

• Size the components, including the pump, motor, and piping, to meet the flow rate and pressure requirements

• Consider factors...read more