900+ Electrical Engineer Interview Questions and Answers

UV Coil provides protection against over voltage and under voltage.

• UV Coil is a device used in electrical systems to protect against voltage fluctuations.

• It monitors the voltage levels and activates when the voltage exceeds or falls below the specified limits.

• When the voltage exceeds the upper limit, the UV Coil disconnects the power supply to prevent damage to the equipment.

• Similarly, when the voltage falls below the lower limit, the UV Coil interrupts the power supply to av...read more

The material with high resistance is an insulator.

• Insulators have high resistance to the flow of electric current.

• Examples of insulating materials include rubber, glass, and plastic.

• Insulators are used to prevent the flow of electricity and protect against electric shocks.

• They are also used in electrical insulation to prevent short circuits.

We can use a Class CT for differential protection.

• Class CTs are commonly used for differential protection in electrical engineering.

• Class CTs provide accurate current measurement and can detect small differences in current flow.

• They are often used in applications such as transformer differential protection and motor protection.

• Class CTs are designed to have a high accuracy and low saturation level to ensure reliable differential protection.

• Examples of Class CTs commonly used ...read more

Identify the problem, gather data, analyze the data, brainstorm solutions, and implement the best solution.

• Define the problem clearly

• Gather data through research and analysis

• Analyze the data to identify the root cause

• Brainstorm potential solutions

• Evaluate and select the best solution

• Implement the solution and monitor its effectiveness

Electrical panels consist of various components such as circuit breakers, fuses, switches, meters, and wires.

• Circuit breakers: protect the electrical system from overloading and short circuits

• Fuses: protect the electrical system from overloading and short circuits

• Switches: control the flow of electricity to different parts of the system

• Meters: measure the amount of electricity being used

• Wires: connect all the components together

• Other components may include transformers, relay...read more

I have experience with specific energy, transformer protections, motor types and starters, and have worked on various projects.

• In my previous company, I worked on optimizing specific energy consumption in electrical systems.

• I am familiar with various transformer protections such as overcurrent, overvoltage, and differential protection.

• I have worked with different types of motors including AC, DC, and stepper motors, and have experience with their starters.

• In my last project, ...read more

LaTeX is a documentation software commonly used for technical and scientific documents.

• LaTeX is a typesetting system commonly used for technical and scientific documents

• It is widely used for academic papers, reports, and presentations

• LaTeX uses markup tags to structure and format documents

• Examples of LaTeX editors include Overleaf, TeXShop, and ShareLaTeX

Power is the rate at which work is done. There are two types of current - AC and DC.

• Power is measured in watts (W)

• AC current changes direction periodically while DC current flows in one direction only

• Examples of AC devices include household appliances while DC devices include batteries and electronic devices

A semiconductor is a material that has electrical conductivity between that of a conductor and an insulator.

• Semiconductors are used in electronic devices such as transistors, diodes, and integrated circuits.

• They have a band gap that allows them to selectively conduct electricity.

• Common examples of semiconductors include silicon, germanium, and gallium arsenide.

Transformer winding resistance can be found using a multimeter and Ohm's law.

• Disconnect the transformer from the power source

• Measure the resistance of each winding using a multimeter

• Use Ohm's law to calculate the exact value of the resistance

• Resistance = Voltage / Current

• Check the manufacturer's specifications for the expected resistance values

Minimum insulation resistance value for HT motor.

• HT motor insulation resistance should be at least 1 Mega Ohm

• Insulation resistance should be measured regularly to ensure safety

• Factors like temperature and humidity can affect insulation resistance

Basic electrical skills include knowledge of circuits, wiring, and electrical safety.

• Understanding of Ohm's law and circuit analysis

• Ability to read and interpret electrical schematics

• Familiarity with electrical codes and regulations

• Knowledge of electrical safety practices

• Proficiency in using electrical tools and equipment

• Experience with troubleshooting electrical systems

Grounding is the process of connecting an electrical circuit to the ground, while earthing is the process of connecting a conductive object to the earth.

• Grounding is done to protect people and equipment from electrical faults and lightning strikes.

• Earthing is done to prevent electric shocks and to ensure the safety of people and equipment.

• Grounding is usually done by connecting a wire from the electrical circuit to a grounding electrode, such as a metal rod driven into the gr...read more

Wind turbines convert wind energy into electricity. IGBT stands for Insulated Gate Bipolar Transistor, used in power electronics.

• Wind turbines use blades to capture wind energy and convert it into rotational motion.

• The rotational motion drives a generator to produce electricity.

• IGBTs are semiconductor devices used in power electronics to switch high power loads efficiently.

• IGBTs are commonly used in variable frequency drives, renewable energy systems, and electric vehicles.

Inrush current is the initial surge of current that flows when an electrical device is first turned on.

• Inrush current occurs due to the charging of capacitive loads and magnetization of inductive loads.

• Inrush current can cause voltage drops, tripping of circuit breakers, and damage to electrical components.

• Inrush current can be reduced by using soft-start circuits, pre-charging capacitors, and selecting appropriate fuses.

• Examples of devices that generate inrush current includ...read more

The phase voltage of a 3-phase system in India for distribution is typically 415 volts.

• Phase voltage in India for distribution is usually 415 volts

• This voltage is commonly used for industrial and commercial applications

• It is important to consider the phase voltage when designing electrical systems

Earthing procedures involve connecting electrical systems to the ground to prevent electric shock and ensure safety. Earthgrid is a network of interconnected grounding systems.

• Earthing procedures involve connecting electrical systems to the ground using conductors like copper rods or plates.

• The purpose of earthing is to prevent electric shock by providing a path for fault currents to flow safely into the ground.

• Earthgrid is a network of interconnected grounding systems that e...read more

Material inspection of electrical projects involves checking the quality and specifications of materials used in the project.

• Verify that materials meet project specifications and standards

• Inspect materials for damage or defects

• Check for proper labeling and documentation

• Ensure materials are stored and handled correctly

• Perform tests or measurements on materials as needed

• Examples: checking the gauge and insulation of electrical wires, inspecting the quality of circuit breakers a...read more

Plant EHT system and single line diagram of plants.

• EHT system refers to Extra High Tension system used in power plants

• Single line diagram shows the electrical connections between different components

• It is important to have a clear and accurate diagram for safety and maintenance purposes

Circuit breakers are safety devices that protect electrical circuits from damage caused by overload, short circuit, or ground fault.

• Circuit breakers are used to prevent damage to electrical equipment and wiring.

• They interrupt the flow of electricity when there is an overload, short circuit, or ground fault.

• Circuit breakers are commonly used in homes, businesses, and industrial settings.

• They come in different sizes and ratings depending on the application.

• Examples of circuit b...read more

A contactor is an electrical switch used for switching an electrical circuit on or off.

• It is used to control electric motors, lighting, heating, and other electrical loads.

• It consists of a coil, contacts, and an enclosure.

• The coil generates a magnetic field that pulls the contacts together to close the circuit.

• Examples include HVAC systems, elevators, and industrial machinery.

• Contactor ratings are based on the amount of current they can handle and the voltage they can switch....read more

Electrical engineers deal with electrical systems while mechanical engineers deal with mechanical systems.

• Electrical engineers work with electricity, electronics, and electromagnetism while mechanical engineers work with mechanics, thermodynamics, and materials science.

• Electrical engineers design and develop electrical systems such as power generation and distribution systems, communication systems, and control systems.

• Mechanical engineers design and develop mechanical system...read more

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

• Transformers are used to increase or decrease voltage levels in electrical circuits.

• There are two main types of transformers: step-up transformers and step-down transformers.

• Step-up transformers increase voltage levels, while step-down transformers decrease voltage levels.

• Examples of transformers include power transformers used in electrical substations an...read more

The 3 tier breaker interlock scheme is used to ensure safe and efficient power distribution from different sources.

• The scheme involves three levels of protection to prevent power overload and equipment damage.

• The first tier involves interlocking the main breaker with the emergency stop button to quickly shut off power in case of an emergency.

• The second tier involves interlocking the main breaker with the VFD and starter to prevent simultaneous operation and overload.

• The third...read more

A tower crane is a type of crane used in construction to lift heavy materials and equipment to great heights.

• Tower cranes are typically used in high-rise building construction.

• They have a long horizontal jib with a hook on the end that can be raised and lowered.

• The crane is mounted on a large concrete base that is anchored to the ground.

• The operator sits in a cab at the top of the crane and controls its movements.

• Tower cranes are essential for lifting heavy materials like ste...read more

Star and delta connections are two types of three-phase circuits used in electrical engineering.

• Star connection has a common neutral point and three phases connected to it.

• Delta connection has three phases connected in a triangular shape.

• Star connection is used for low voltage applications while delta connection is used for high voltage applications.

• Star connection provides better safety as the neutral point can be grounded.

• Delta connection provides higher power output but is...read more

VCB and ACB transformers require regular maintenance to ensure optimal performance and prevent breakdowns.

• Regular inspection of the transformer and its components

• Cleaning of the transformer and its components

• Checking and tightening of connections

• Testing of protective devices

• Replacement of worn out or damaged parts

• Regular oil analysis

• Following manufacturer's recommended maintenance schedule

• Training of personnel on proper maintenance procedures

Mechatronics is a multidisciplinary field that combines mechanical, electrical, and computer engineering to design and develop intelligent systems.

• Mechatronics is used in industries such as automotive, aerospace, robotics, and manufacturing.

• It involves the integration of sensors, actuators, and controllers to create smart machines and systems.

• Examples of mechatronic systems include self-driving cars, industrial robots, and automated manufacturing equipment.

• Mechatronics also p...read more

The motor winding resistance of a 100 HP motor is higher than that of a 10 HP motor.

• Motor winding resistance is typically higher in larger motors due to the increased power output.

• Higher HP motors have thicker wire and more coils in their windings, resulting in higher resistance.

• For example, a 100 HP motor may have a winding resistance of 0.1 ohms, while a 10 HP motor may have a winding resistance of 0.01 ohms.

Comparators are electronic circuits that compare two voltages and output a digital signal based on the comparison. Band pass filter circuit allows only a certain range of frequencies to pass through.

• Comparators are used in applications such as voltage level detection, waveform shaping, and pulse width modulation.

• They have two input terminals for the voltages to be compared and one output terminal for the digital signal.

• Band pass filter circuit consists of a combination of hig...read more

Safety measures during installation work in a rooftop project

• Ensure proper training and certification for working at heights

• Use appropriate personal protective equipment (PPE) such as helmets, safety harnesses, and non-slip footwear

• Secure the work area with barriers or guardrails to prevent falls

• Inspect and maintain all equipment and tools regularly

• Follow electrical safety protocols and use insulated tools when working with electrical components

• Implement a lockout/tagout syst...read more

Types of GI top channels, cross angles, types of DTR, rating of DTR, current capacity of DTRs.

• Types of GI top channels include GI plain channels and GI perforated channels.

• Cross angles are used to provide additional support and stability to structures.

• Types of DTR (Distribution Transformer Rectifier) include single-phase and three-phase.

• Rating of DTR is typically in kVA (kilo Volt-Ampere) and can range from 25 kVA to 2000 kVA.

• Current capacity of DTRs varies based on the ratin...read more

Home load of a power plant is received through a distribution network.

• Home load is received from the power plant through a distribution network.

• The power plant generates electricity and sends it to a substation.

• The substation then distributes the electricity to homes through power lines.

• The distribution network ensures that the electricity reaches each home efficiently.

• Examples of distribution networks include overhead power lines and underground cables.

CB is a switch that can interrupt the circuit during fault conditions, while an isolator is a switch that can only isolate the circuit.

• CB is used for protection against overcurrent, short circuit, and earth fault

• Isolator is used for isolation of a circuit for maintenance or repair work

• CB can be operated manually or automatically, while isolator is operated manually only

• CB has contacts that can break the circuit, while isolator has no such contacts

Efficiency of a transformer is maximum when the copper losses are equal to iron losses.

• Efficiency is maximum when the transformer is operating at its full load capacity.

• Copper losses are caused by the resistance of the wire used in the transformer's windings.

• Iron losses are caused by the magnetic properties of the transformer's core.

• Efficiency can be improved by using high-quality materials and reducing the air gap between the core and windings.

• Efficiency can also be improved...read more

Reverse arc flashing on ACB breaker refers to the phenomenon where the arc flash occurs on the opposite side of the contacts during the opening operation.

• Reverse arc flashing happens when the arc flash occurs on the side of the contacts opposite to the normal direction during the opening operation of the ACB breaker.

• This phenomenon can be caused by factors such as high fault currents, improper maintenance, or inadequate arc flash protection.

• Reverse arc flashing can pose a saf...read more

The current carrying capacity of a 185sqmm al cable depends on various factors such as the material, insulation, and installation method.

• The current carrying capacity of a cable is typically determined by the manufacturer and specified in the cable's datasheet.

• Factors such as the material (aluminum in this case), insulation type, ambient temperature, and installation method all affect the current carrying capacity.

• For a 185sqmm aluminum cable, the current carrying capacity ca...read more

The number of turns in the primary coil

• The number of turns in the primary coil remains constant

• The voltage-frequency ratio is constant

• The power input and output are not equal due to losses

• The transformer efficiency can change based on load

An AC drive circuit diagram controls the speed of an AC motor by varying the frequency and voltage of the power supplied to it.

• An AC drive consists of a rectifier, DC link, inverter, and control circuitry.

• The rectifier converts AC power to DC power, which is stored in the DC link.

• The inverter converts the DC power back to AC power with variable frequency and voltage.

• The control circuitry adjusts the frequency and voltage of the output to control the motor speed.

• Examples of AC...read more

To test IGBT in an a.c drive, perform insulation resistance test, gate voltage test, and current-voltage characteristics test.

• Perform insulation resistance test to check for any leakage or insulation breakdown.

• Conduct gate voltage test to ensure proper functioning of the gate driver circuit.

• Test the current-voltage characteristics to verify the IGBT's performance under different load conditions.

• Use an oscilloscope to analyze the waveforms and check for any abnormalities.

• Perfo...read more

One horsepower is equal to approximately 746 watts.

• One horsepower is a unit of power commonly used to measure the output of engines and motors.

• It is equivalent to approximately 746 watts.

• The conversion factor between horsepower and watts is 746.

• For example, a 1 horsepower motor would consume or produce approximately 746 watts of power.

SAT (Site Acceptance Test) is done for cables to ensure their healthiness.

• SAT is a series of tests performed on cables to verify their performance and functionality.

• It includes tests like insulation resistance, continuity, voltage withstand, and cable length measurement.

• SAT helps in identifying any faults or defects in the cables and ensures their proper functioning.

• For example, in power transmission systems, SAT is conducted to ensure the cables can handle the required volta...read more

An induction motor is an AC electric motor in which power is supplied to the rotor by electromagnetic induction.

• Induction motors are widely used in various applications, including industrial machinery, household appliances, and transportation systems.

• They work based on the principle of electromagnetic induction, where a rotating magnetic field is created by the stator winding, inducing current in the rotor.

• The rotor of an induction motor can be either squirrel cage or wound t...read more

The starting current of an induction motor is typically 5 to 7 times the rated current.

• The starting current of an induction motor is higher than its rated current.

• The exact starting current depends on the motor design and load conditions.

• Starting current can be 5 to 7 times the rated current for most induction motors.

• High starting currents can cause voltage drops and affect the stability of the electrical system.

• Motor starters and soft starters are used to limit the starting ...read more

Electrical systems and components are essential for the functioning of various electrical devices and equipment.

• Electrical systems consist of various components such as transformers, generators, motors, and circuit breakers.

• These components work together to convert electrical energy into usable forms and distribute it to different parts of the system.

• Electrical systems can be AC or DC, and can be used in a variety of applications such as power generation, transmission, and di...read more

DMZ is a network segment that separates an internal network from an external network.

• DMZ stands for Demilitarized Zone.

• It acts as a buffer zone between the internet and the internal network.

• It contains servers that are accessible from the internet, but not the internal network.

• It enhances security by limiting direct access to the internal network.

• Examples of servers in DMZ include web servers, email servers, and FTP servers.

Motors require a load to convert electrical energy into mechanical energy.

• A motor works by converting electrical energy into mechanical energy

• The load is the object that the motor is designed to move or operate

• Without a load, the motor may spin uncontrollably or not at all

• Examples of loads include fans, pumps, conveyor belts, and elevators