50+ Coal India Interview Questions and Answers

The camshaft and crankshaft have different speeds in an engine.

• The camshaft controls the opening and closing of the engine's valves, while the crankshaft converts the reciprocating motion of the pistons into rotational motion.

• The camshaft rotates at half the speed of the crankshaft in a four-stroke engine.

• For example, if the crankshaft rotates at 6000 revolutions per minute (RPM), the camshaft will rotate at 3000 RPM.

• The speed difference is necessary to ensure proper valve ti...read more

The maximum width of the gallery in Indian coal mines varies depending on the specific mine and its regulations.

• The maximum width of the gallery is determined by safety regulations and guidelines set by the Indian government.

• Different coal mines may have different maximum width requirements based on factors such as the type of coal being mined, the depth of the mine, and the mining method used.

• For example, in underground longwall mining, the gallery width may range from 3 to ...read more

Discontinuous chips are formed in certain materials during machining processes.

• Discontinuous chips are formed in brittle materials like cast iron, ceramics, and glass.

• These materials have low ductility and tend to fracture during machining.

• The discontinuous chips have a segmented or broken appearance.

• They are characterized by irregular shapes and rough surfaces.

• Examples of materials that form discontinuous chips include graphite, tungsten carbide, and certain types of plastic...read more

Copper loss in a transformer decreases when it operates at half its rated MVA.

• Copper loss is directly proportional to the square of the current flowing through the windings.

• When the transformer operates at half its rated MVA, the current flowing through the windings is reduced.

• As a result, the copper loss in the transformer decreases.

• This reduction in copper loss leads to improved efficiency and lower energy consumption.

CNC stands for Computer Numerical Control. It is a manufacturing process that uses pre-programmed computer software to control machine tools.

• CNC is a manufacturing process that automates the operation of machine tools.

• It uses computer software to control the movement and operation of the machines.

• CNC machines are widely used in industries such as automotive, aerospace, and electronics.

• G codes are a programming language used in CNC to control the movement, speed, and position ...read more

Industry 4.0 is the fourth industrial revolution characterized by the integration of digital technologies into manufacturing processes.

• Industry 4.0 refers to the use of automation, data exchange, and IoT in manufacturing.

• ECC stands for Enterprise Core Component and is a framework for managing business processes in SAP systems.

• Edge computing is a decentralized computing infrastructure that brings computation and data storage closer to the location where it is needed.

• TDI model ...read more

Stripping ratio is the amount of waste rock removed to extract one unit of ore. Workable range for an OCP is typically between 1:1 to 10:1.

• Stripping ratio is calculated by dividing the amount of waste rock by the amount of ore extracted.

• A lower stripping ratio indicates a more efficient mining operation.

• For an Open Cut Pit (OCP), the workable range for stripping ratio is usually between 1:1 to 10:1.

• For example, if a mine has a stripping ratio of 3:1, it means that for every 3...read more

The suitable bench height for a 2cu.m shovel depends on various factors such as the type of material being mined and the equipment used.

• The bench height should be determined based on the reach and capacity of the shovel.

• It should allow for efficient loading and dumping of material.

• The bench height should also consider the stability and safety of the mining operation.

• Factors like the type of material, equipment limitations, and slope stability analysis should be considered.

• For...read more

A wound rotor induction motor can provide high starting torque and high efficiency.

• Wound rotor induction motors have a higher starting torque compared to squirrel cage induction motors.

• The rotor windings in a wound rotor motor can be connected to external resistors, allowing for higher torque during startup.

• By adjusting the resistance in the rotor circuit, the motor can achieve high efficiency at full load.

• Examples of applications where high starting torque and efficiency are...read more

The output capacity of the dragline with 4.5 to 7.5 cu.m is in million cu.m per year.

• The output capacity of the dragline depends on the size of the bucket it uses.

• A larger bucket size allows for a higher output capacity.

• The dragline's efficiency and operating conditions also affect its output capacity.

• The output capacity can be calculated by considering the average number of cycles per hour and the bucket fill factor.

• For example, if the dragline completes 10 cycles per hour w...read more

Different types of chips in metal cutting include continuous chips, discontinuous chips, and built-up edge chips.

• Continuous chips are formed when the cutting tool continuously removes material from the workpiece.

• Discontinuous chips are formed when the cutting tool intermittently removes material, resulting in segmented chips.

• Built-up edge chips occur when the material being cut adheres to the cutting tool, forming a built-up layer.

• Other types of chips include serrated chips, ...read more

The lack of high-rise buildings in India can be attributed to various factors such as land availability, building regulations, cultural preferences, and infrastructure limitations.

• Limited availability of land in urban areas restricts the construction of high-rise buildings.

• Building regulations and zoning laws often impose height restrictions and setback requirements.

• Cultural preferences in India often favor low-rise buildings that promote a sense of community and connection w...read more

To reduce problems in an underground tunnel, civil engineers should focus on proper design, construction, and maintenance.

• Ensure proper ventilation to prevent air pollution and maintain air quality.

• Implement effective drainage systems to prevent water accumulation and flooding.

• Use high-quality materials and construction techniques to ensure structural integrity.

• Regularly inspect and maintain the tunnel to identify and address any potential issues.

• Install proper lighting and e...read more

Equipments used in an Open Cast Mine include excavators, dump trucks, bulldozers, drills, and draglines.

• Excavators are used for digging and removing overburden or ore.

• Dump trucks are used for transporting materials within the mine.

• Bulldozers are used for pushing and leveling the ground.

• Drills are used for drilling blast holes for explosives.

• Draglines are used for removing overburden in large quantities.

The maximum length of the trailing cable depends on various factors such as power requirements, voltage drop, and safety regulations.

• The length of the trailing cable is determined by the distance between the power source and the equipment it needs to supply.

• Power requirements of the equipment play a role in determining the maximum length of the cable.

• Voltage drop, which can affect the efficiency of power transmission, is also considered when determining the cable length.

• Safet...read more

Portable machines can be easily carried around, while transportable machines require disassembly and reassembly for transportation.

• Portable machines are designed to be easily moved from one location to another without much effort.

• Transportable machines require disassembly and reassembly for transportation.

• Portable machines are usually smaller and lighter than transportable machines.

• Examples of portable machines include laptops, tablets, and handheld gaming devices.

• Examples of...read more

A haul road is a road used for transporting materials, typically in a mining or construction site.

• Haul roads are designed to handle heavy loads and are often unpaved.

• They are used to transport materials such as ore, rock, and dirt.

• Haul roads must be maintained regularly to ensure safety and efficiency.

• Proper drainage is important to prevent erosion and maintain road stability.

• Examples of haul road equipment include haul trucks, graders, and water trucks.

A sheathed explosive is coated with a protective covering.

• The sheath provides a layer of protection to the explosive material.

• The sheath can be made of materials like plastic or rubber.

• The purpose of the sheath is to prevent accidental ignition or detonation.

• Examples of sheathed explosives include dynamite and blasting caps.

A flame safety lamp is a type of lamp used in mining to detect methane gas and prevent explosions.

• It works by creating a flame inside a mesh screen that will go out if methane is present.

• The lamp was invented by Sir Humphry Davy in 1815.

• It was widely used in coal mines in the 19th and early 20th centuries.

• Today, electronic gas detectors have largely replaced flame safety lamps in mining.

The priming charge in a detonator is the initial explosive charge that initiates the main explosive charge.

• The priming charge is a small amount of explosive material that is sensitive to heat, shock, or friction.

• It is designed to ignite quickly and reliably to initiate the main explosive charge.

• The priming charge is usually contained within a small metal or plastic capsule.

• Examples of priming charges include lead azide, lead styphnate, or PETN.

• The purpose of the priming charg...read more

The VOD of emulsion explosive refers to its Velocity of Detonation.

• VOD is a measure of how fast the explosive reaction propagates through the material.

• It is an important characteristic for determining the efficiency and safety of explosive materials.

• Higher VOD explosives are typically used for blasting hard rock formations.

• Lower VOD explosives are used in situations where a controlled and less destructive explosion is required.

River meandering is the process of a river winding and curving along its course.

• River meandering occurs when a river flows through a flat or gently sloping landscape.

• It happens due to a combination of erosion, deposition, and the flow of water.

• As the river flows, it erodes the outer banks and deposits sediment on the inner banks, causing the river to curve.

• The speed and volume of water, as well as the type of sediment, influence the meandering pattern.

• Meanders can form oxbow ...read more

Yes, Coal India is a state-owned coal mining company with operations in remote locations.

• Coal India Limited is the largest coal-producing company in the world.

• It has mines in remote locations such as Jharkhand, Chhattisgarh, and Odisha.

• The company also has subsidiaries that operate in other countries such as Mozambique and South Africa.

Yes, I am open to being located in a remote location for the right opportunity.

• I am willing to relocate for the right job opportunity

• I have experience working remotely or in different locations

• I am adaptable and can thrive in new environments

Crown pillar & rib are terms used in mining to describe the rock structures above and around a mined-out area.

• Crown pillar is the rock mass above an underground excavation that supports the overlying rock and prevents collapse.

• Rib refers to the rock walls or pillars left between mined-out areas to provide support and prevent collapse.

• Both crown pillar and rib are crucial for the stability and safety of underground mining operations.

• Examples: In a coal mine, the crown pillar m...read more

The gelling agent in slurry explosive is typically a mixture of water and a thickening agent.

• The gelling agent is used to increase the viscosity of the explosive mixture.

• Common thickening agents used in slurry explosives include guar gum, carboxymethyl cellulose (CMC), and xanthan gum.

• The gelling agent helps to suspend solid particles in the explosive mixture, allowing for better distribution and control of the explosive energy.

• The choice of gelling agent depends on factors s...read more

Safety devices of Direct Haulage include emergency stop buttons, warning signals, and safety barriers.

• Emergency stop buttons are installed at regular intervals along the haulage route.

• Warning signals such as flashing lights and alarms are used to alert workers of approaching haulage equipment.

• Safety barriers are used to prevent workers from entering hazardous areas.

• Proximity detection systems are used to detect the presence of workers and automatically stop the haulage equipm...read more

Types of inventory analysis, willingness to relocate, reason for leaving current job

• Types of inventory analysis include ABC analysis, XYZ analysis, and cycle counting

• I am willing to relocate to mining areas for career growth and new opportunities

• I am leaving my current job to seek a more challenging role with greater responsibilities

Detonating fuse consists of a core

• The core of a detonating fuse is the central part that initiates the explosion

• The core is typically made of a highly reactive material, such as a mixture of powdered metals or chemicals

• The core is surrounded by a protective casing to prevent accidental ignition

• Examples of core materials include lead azide, mercury fulminate, or PETN

The VOD of detonating fuse is the velocity at which the detonation wave travels along the fuse.

• VOD stands for Velocity of Detonation.

• It is a measure of how fast the detonation wave propagates through the fuse.

• The VOD of a detonating fuse depends on factors such as the type of explosive used and the composition of the fuse.

• A higher VOD means the detonation wave travels faster, resulting in a quicker explosion.

• Different types of detonating fuses may have different VOD values.

Sharp corners are avoided in casting to prevent stress concentration and improve the overall strength and quality of the casting.

• Sharp corners can lead to stress concentration, which can cause cracks or failure in the casting.

• Rounded corners distribute stress more evenly, reducing the likelihood of defects.

• Sharp corners can also create difficulties during the casting process, such as mold filling and solidification issues.

• Examples of avoiding sharp corners include filleting o...read more

The calorific value of coal varies depending on the type of coal, but typically ranges from 24 to 30 megajoules per kilogram.

• Calorific value is the amount of heat released when a substance is burned.

• It is measured in units of energy per unit of mass, such as joules per gram or megajoules per kilogram.

• The calorific value of coal can vary depending on factors such as moisture content, ash content, and sulfur content.

• For example, anthracite coal has a higher calorific value than...read more

Estimating wiring and connections in a building involves assessing the electrical needs and layout of the space.

• Assess the electrical needs of the building, including the number of outlets, lighting fixtures, and appliances.

• Determine the layout of the building and the best routes for wiring to avoid hazards and maximize efficiency.

• Consider the type of wiring needed, such as copper or aluminum, and the appropriate gauge for the electrical load.

• Ensure compliance with local buil...read more

To find the steel weight, you need to know the dimensions and density of the steel.

• Determine the dimensions of the steel (length, width, and height)

• Find the density of the specific type of steel being used

• Multiply the volume of the steel by its density to calculate the weight

• Weight (in kg) = Volume (in m^3) x Density (in kg/m^3)

I can add value from my previous experience by implementing successful marketing strategies, analyzing market trends, and building strong relationships with clients.

• Implemented successful marketing strategies to increase sales by 20% in my previous role

• Analyzed market trends to identify new opportunities for product development

• Built strong relationships with clients resulting in a 30% increase in customer retention

There are 100 centimetres in one metre.

• One metre is equal to 100 centimetres.

• To convert metres to centimetres, multiply by 100.

• To convert centimetres to metres, divide by 100.

Fans are used in mines to provide ventilation and circulate air to maintain a safe and comfortable working environment for miners.

• Fans are typically installed at the surface or underground to draw in fresh air and remove stale air from the mine workings.

• The fan blades rotate to create airflow, which helps to dilute and remove harmful gases, dust, and fumes from the mine.

• Proper ventilation with fans also helps to control temperature and humidity levels in the mine.

• Fans can be ...read more

Cables that transfer power are of different types depending on the application.

• AC power cables

• DC power cables

• Coaxial cables

• Ethernet cables

• USB cables

• HDMI cables

• Optical fiber cables

An induction motor is a type of AC motor that works on the principle of electromagnetic induction to convert electrical energy into mechanical energy.

• Induction motors are commonly used in various industrial applications due to their simplicity, reliability, and low cost.

• They consist of a stator (stationary part) and a rotor (rotating part) where the rotor is not connected to an external power source.

• When an alternating current is applied to the stator windings, a rotating mag...read more

Distribution transformer rating is the maximum power it can handle without overheating.

• Distribution transformer rating is expressed in kVA (kilovolt-ampere).

• It is important to choose the right rating for the transformer based on the load requirements.

• The rating of a transformer can be determined by calculating the load requirements of the system it is being installed in.

• For example, if the load requirement is 500 kVA, a transformer with a rating of 600 kVA should be chosen to...read more

Substation use equipment refers to the various devices and tools used in a substation for power distribution and maintenance.

• Substation transformers

• Circuit breakers

• Disconnect switches

• Voltage regulators

• Capacitor banks

• Protective relays

A generator is a device that converts mechanical energy into electrical energy. It functions by rotating a coil of wire within a magnetic field to produce electricity.

• Generates electricity by converting mechanical energy into electrical energy

• Consists of a coil of wire rotating within a magnetic field

• Used in power plants, backup generators, and portable generators

Transformers function to change voltage levels in electrical systems.

• Transformers increase or decrease voltage levels in electrical systems

• Step-up transformers increase voltage for long-distance transmission

• Step-down transformers decrease voltage for distribution to homes and businesses

• Transformers help maintain power quality and efficiency in electrical grids

A hydraulic system is a technology that uses liquid to transmit force and energy.

• Uses incompressible fluid to generate power

• Consists of hydraulic fluid, pump, valves, cylinders, and motors

• Commonly used in heavy machinery like dump trucks and excavators

A transformer is an electrical device that transfers electrical energy from one circuit to another through electromagnetic induction.

• Transformers are used to increase or decrease the voltage of an alternating current (AC) power supply.

• They consist of two coils of wire, known as the primary and secondary coils, which are wrapped around a magnetic core.

• When an AC voltage is applied to the primary coil, it creates a magnetic field that induces a voltage in the secondary coil.

• Tra...read more

Single phase motors are commonly used in household appliances and small machinery.

• Split-phase motor

• Capacitor-start motor

• Capacitor-run motor

• Shaded-pole motor

MCB is a miniature circuit breaker while MCCB is a molded case circuit breaker.

• MCB is used for low current applications while MCCB is used for high current applications.

• MCB is rated up to 100 amps while MCCB can be rated up to 2500 amps.

• MCCB has adjustable trip settings while MCB does not.

• MCCB is more expensive than MCB.

• Examples of MCB brands include Legrand and Schneider while examples of MCCB brands include Siemens and ABB.

Treatment for TB involves a combination of antibiotics taken for several months.

• Treatment for TB typically involves a combination of antibiotics such as isoniazid, rifampin, ethambutol, and pyrazinamide.

• The duration of treatment can vary but is usually around 6 to 9 months.

• Directly Observed Therapy (DOT) is often recommended to ensure adherence to the treatment regimen.

• Patients with drug-resistant TB may require different medications and longer treatment duration.

• Treatment sh...read more

Safety is the practice of ensuring that people, equipment, and the environment are protected from harm or danger.

• Safety involves following rules and procedures to prevent accidents and injuries

• It includes wearing appropriate protective gear, such as helmets or safety vests

• Regular maintenance of equipment and machinery is essential for safety

• Safety also involves being aware of potential hazards and taking steps to mitigate risks

• Training and communication are key components of ...read more

The type of breaker used depends on the electrical load and the circuit requirements.

• The most common types of breakers are standard, AFCI, GFCI, and dual-function.

• Standard breakers are used for general-purpose circuits.

• AFCI breakers are used for circuits that power bedrooms and living rooms.

• GFCI breakers are used for circuits that power bathrooms, kitchens, and outdoor areas.

• Dual-function breakers combine AFCI and GFCI protection.

• The size of the breaker is determined by the a...read more

Coal India is the largest coal-producing company in the world, with a strong market presence and growth potential.

• Coal India has a dominant position in the coal industry, accounting for over 80% of India's coal production.

• The company has a vast reserve base and a strong distribution network, ensuring a steady supply of coal to meet market demand.

• Coal India has a history of consistent growth and profitability, making it an attractive choice for career growth and development.

• Wo...read more

Electricity is the flow of electric charge through a conductor.

• Electricity is the flow of electrons through a conductor

• It is a form of energy that powers electrical devices

• Electricity can be generated from various sources such as coal, wind, solar, and hydro

• It is measured in units of volts, amps, and watts