900+ Electrical Engineer Interview Questions and Answers

Switchgear is a combination of electrical disconnect switches, fuses, or circuit breakers used to control, protect, and isolate electrical equipment.

• Switchgear is a general term for a collection of devices used to control, protect, and isolate electrical equipment.

• Circuit breakers are a type of switchgear that automatically interrupts the flow of electric current when a fault is detected.

• Switchgear can include disconnect switches, fuses, circuit breakers, relays, and other de...read more

ATS stands for Automatic Transfer Switch. It is used to transfer power supply between two sources. Transformer and motor maintenance procedures and protection methods are essential for their efficient operation. SAP is a software used for enterprise resource planning.

• ATS is used to automatically switch power supply between two sources, ensuring uninterrupted power supply.

• Transformer maintenance involves regular inspection, cleaning, and testing of transformer components.

• Trans...read more

Composite error and ratio error are two types of errors in current transformers.

• Composite error is the combination of ratio error and phase angle error in a current transformer.

• Ratio error is the difference between the actual turns ratio and the specified turns ratio of a current transformer.

• Phase angle error is the angular difference between the primary and secondary currents of a current transformer.

• Composite error and ratio error affect the accuracy of current measurement ...read more

The question covers power factor of transformer, types of DC machine, working principle of AC alternator, and DC motors.

• Power factor of a transformer is the ratio of real power to apparent power.

• Types of DC machines include DC motors and DC generators.

• AC alternators work on the principle of electromagnetic induction to convert mechanical energy into electrical energy.

• DC motors convert electrical energy into mechanical energy through the interaction of magnetic fields.

The capacity of the transformer in our plant is 500 kVA.

• Our plant's transformer has a capacity of 500 kVA.

• This allows us to efficiently power our equipment and machinery.

• We regularly maintain and monitor the transformer to ensure optimal performance.

The chance of survival depends on various factors such as insulation, grounding, and the strength of the electrical surge.

• The chance of survival depends on the insulation of the car, as it acts as a barrier against electrical current.

• If the car is properly grounded, it can help dissipate the electrical surge and reduce the risk of injury.

• The strength of the electrical surge also plays a crucial role in determining the chance of survival.

• If the car has safety features like lig...read more

Transformers are protected by various methods to prevent damage from faults and overloads.

• Overcurrent protection using fuses or circuit breakers

• Thermal protection using temperature sensors and alarms

• Buchholz relay protection for detecting internal faults

• Differential protection for detecting external faults

• Ground fault protection using ground fault relays

• Lightning arrestors for protection against lightning strikes

• Oil level and pressure monitoring for preventing oil leaks and e...read more

The interface between transformer and switch gears is the electrical connection and communication between the two components.

• The transformer and switch gears are connected through electrical cables or busbars.

• The switch gears control the flow of electrical power to and from the transformer.

• The switch gears may include circuit breakers, relays, and protective devices.

• The interface ensures proper coordination and protection of the transformer and switch gears.

• Communication betw...read more

Earthing is necessary for all electrical equipments to ensure safety and prevent electrical hazards.

• Earthing provides a path for the fault current to flow safely into the ground.

• It helps in preventing electric shocks by providing a low-resistance path for the current to flow in case of a fault.

• Earthing helps in stabilizing the voltage levels and reducing the risk of electrical fires.

• It protects the equipment from damage caused by lightning strikes or power surges.

• Earthing als...read more

Power transformers are used in transmission systems to step up or down voltage, while distribution transformers are used in distribution systems to step down voltage.

• Power transformers are used in high voltage transmission systems to step up or down voltage for long distance transmission.

• Distribution transformers are used in low voltage distribution systems to step down voltage for local distribution.

• Power transformers have higher voltage ratings and power capacities than dis...read more

De-rating factors and considerations for cable sizing calculations in electrical engineering.

• De-rating factors include ambient temperature, grouping, soil thermal resistivity, and cable installation method.

• Ambient temperature affects the cable's current carrying capacity.

• Grouping of cables can lead to increased heat generation and reduced current carrying capacity.

• Soil thermal resistivity affects the heat dissipation capability of buried cables.

• Cable installation methods such...read more

Transformers work on the principle of electromagnetic induction to transfer electrical energy between two or more circuits.

• Transformers consist of two or more coils of wire called windings.

• When an alternating current (AC) flows through the primary winding, it creates a changing magnetic field.

• This changing magnetic field induces a voltage in the secondary winding, which is connected to the load.

• The ratio of the number of turns in the primary and secondary windings determines ...read more

My strength programming language is C++. I have extensive experience in developing software and solving complex problems using C++.

• Proficient in object-oriented programming with C++

• Strong knowledge of data structures and algorithms

• Experience in developing efficient and scalable code

• Familiarity with C++ libraries and frameworks

• Ability to debug and optimize code for performance

• Experience in multi-threading and parallel programming

• Knowledge of C++ best practices and coding stand...read more

Blocked rotor test is performed on a 3-phase induction motor to determine its impedance and calculate its locked rotor current.

• The motor is connected to a 3-phase supply with the rotor blocked.

• The voltage and current are measured and used to calculate the motor's impedance.

• The locked rotor current can be determined from the impedance.

• The test helps in assessing the motor's performance and identifying any faults or issues.

The formula for cross section of earthing conductor and depth of burying the strip or bare earthing conductor.

• The formula for cross section of earthing conductor is determined by the maximum fault current and the allowable touch voltage.

• The depth of burying the strip or bare earthing conductor depends on factors such as soil resistivity and the type of installation.

• The cross section of earthing conductor can be calculated using the formula: Cross Section = (Fault Current x Le...read more

Neutral is a current-carrying conductor that completes an electrical circuit, while earth is a safety grounding conductor.

• Neutral carries current back to the source in a balanced electrical system.

• Earth is a safety measure to prevent electric shock and protect against electrical faults.

• Neutral is typically connected to the center tap of a transformer, while earth is connected to the ground.

• Neutral is part of the electrical distribution system, while earth is a safety feature....read more

Over current protection, differential protection, and earth fault protection are methods used to safeguard electrical systems.

• Over current protection is used to detect and interrupt excessive current flow in a circuit.

• Differential protection compares the current entering and leaving a component to detect faults.

• Earth fault protection detects current leakage to the earth and isolates the faulty circuit.

• Over current protection devices include fuses, circuit breakers, and relays...read more

A string of transistors in series is used to increase the overall voltage gain of a circuit.

• Transistors in series amplify the input signal sequentially, resulting in a higher overall gain.

• This configuration is commonly used in amplifiers and signal processing circuits.

• For example, a cascade amplifier consists of multiple stages of transistors in series to achieve high gain.

• Each transistor in the series contributes to the overall amplification of the signal.

Series reactors are used in transmission lines to limit the flow of current and improve system stability.

• Series reactors are used to limit the flow of current in a transmission line.

• They improve system stability by reducing voltage fluctuations and power surges.

• They can also be used to compensate for line capacitance and improve power factor.

• Examples of series reactors include air-core reactors, iron-core reactors, and hybrid reactors.

• They are commonly used in high-voltage tr...read more

The company culture at Maruti Suzuki is focused on innovation, teamwork, and customer satisfaction.

• Maruti Suzuki encourages innovation and creativity among its employees.

• Teamwork is highly valued, with employees collaborating to achieve common goals.

• Customer satisfaction is a top priority, with a strong emphasis on delivering high-quality products and services.

• The company promotes a culture of continuous learning and development.

• Maruti Suzuki values diversity and inclusion, f...read more

Transformers are electrical devices that transfer energy from one circuit to another through electromagnetic induction.

• Transformers work on the principle of electromagnetic induction

• They consist of two coils, primary and secondary, wound around a magnetic core

• When an alternating current flows through the primary coil, it creates a magnetic field which induces a voltage in the secondary coil

• Transformers are used to step up or step down voltage levels in power transmission and ...read more

Substations use various equipment for power distribution and control.

• Transformers: Step up or step down voltage levels.

• Circuit breakers: Protect the system from overloads and faults.

• Switchgear: Control and isolate electrical circuits.

• Busbars: Distribute power to different parts of the substation.

• Relays: Monitor and protect the system from abnormalities.

• Capacitors: Improve power factor and voltage stability.

• Disconnect switches: Safely isolate equipment for maintenance.

• Instrume...read more

You are standing at the North Pole.

• Walking one mile south takes you one mile away from the North Pole.

• Walking one mile west takes you in a circle around the North Pole.

• Walking one mile north brings you back to the North Pole, where you started.

CT and PT are electrical transformers used in power systems to measure current and voltage respectively.

• CT stands for Current Transformer and is used to measure high currents in power systems.

• PT stands for Potential Transformer and is used to measure high voltages in power systems.

• CTs are connected in series with the load while PTs are connected in parallel with the load.

• CTs are used to measure current for protection and metering purposes while PTs are used for metering and c...read more

VCB, SF6, CT, PT, LA are all electrical equipment used in power systems.

• VCB stands for Vacuum Circuit Breaker and is used for switching and protection of electrical power systems.

• SF6 is a gas used as an insulating medium in high voltage electrical equipment such as circuit breakers, switchgear, and transformers.

• CT stands for Current Transformer and is used to measure electrical current in power systems.

• PT stands for Potential Transformer and is used to measure electrical volt...read more

Criteria for evaluating cable thickness and length in electrical engineering.

• Consider the current carrying capacity of the cable

• Evaluate the voltage drop over the length of the cable

• Take into account the environmental conditions where the cable will be installed

• Check the insulation material and its thickness

• Ensure the cable length is sufficient for the intended application

The main types of electrical currents are AC and DC.

• AC (alternating current) changes direction periodically and is used in household electricity.

• DC (direct current) flows in one direction and is used in batteries and electronic devices.

• Other types of currents include pulsed DC and sinusoidal AC.

• The choice of current type depends on the application and the equipment being used.

Transistors are primarily used to amplify and switch electric currents in electronic devices.

• Transistors are essential components in electronic circuits.

• They can amplify weak signals to a higher power level.

• Transistors can also act as switches, controlling the flow of current.

• They are used in various applications such as amplifiers, radios, computers, and televisions.

• Examples of transistors include bipolar junction transistors (BJTs) and field-effect transistors (FETs).

I have used several development tools throughout my career.

• I have experience with IDEs such as Eclipse, Visual Studio, and Xcode.

• I have used version control systems like Git and SVN.

• I am familiar with debugging tools like GDB and LLDB.

• I have worked with simulation tools like LTSpice and MATLAB.

• I have also used various programming languages and frameworks such as C++, Java, Python, and Django.

A circuit breaker is an electrical switch that automatically interrupts the flow of current when it exceeds a certain limit.

• It is used to protect electrical circuits from damage caused by overloading or short circuits.

• It works by detecting the excess current and tripping the switch to break the circuit.

• It can be reset manually or automatically depending on the type of circuit breaker.

• Examples include thermal circuit breakers, magnetic circuit breakers, and hydraulic-magnetic ...read more

SAP procedure for UPS vendor is a process for managing vendor data in the SAP system.

• The SAP procedure for UPS vendor involves creating and maintaining vendor master data in the system.

• It includes defining vendor attributes such as payment terms, delivery schedules, and contact information.

• The procedure also involves creating purchase orders and managing invoices from the vendor.

• Examples of UPS vendors include APC, Eaton, and Tripp Lite.

An LPG plant is a facility that processes and stores liquefied petroleum gas. It requires various electrical and electronic equipment for its operations.

• LPG plant is a facility that processes and stores liquefied petroleum gas

• Electrical equipment in an LPG plant includes transformers, switchgear, motors, and control panels

• Electronic equipment in an LPG plant includes sensors, transmitters, and PLCs

• Examples of electrical equipment: power distribution systems, motor control cen...read more

Transformer PM involves regular maintenance and inspection to ensure optimal performance.

• Perform regular visual inspections to check for signs of wear and tear

• Test insulation resistance to ensure it meets standards

• Check oil levels and perform oil analysis to detect any contaminants

• Inspect and tighten connections

• Perform load and temperature tests

• Schedule maintenance based on manufacturer recommendations

• Examples of maintenance tasks include cleaning, lubrication, and replacing ...read more

I am comfortable working with Windows, Linux and MacOS operating systems.

• Proficient in Windows OS and its various versions

• Familiar with Linux OS and its distributions like Ubuntu, Fedora, and CentOS

• Experienced in MacOS and its versions like Mojave and Catalina

Electricity is the flow of electrons through a conductor.

• Electricity is a form of energy that powers most of our modern devices.

• It is generated by various sources such as power plants, batteries, and solar panels.

• Electricity can be dangerous and must be handled with caution.

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

• Examples of electrical devices include light bulbs, computers, and refrigerators.

The electrical equipment in our plant includes generators, transformers, switchgear, motors, control panels, and lighting fixtures.

• Generators: Used to produce electrical power.

• Transformers: Used to step up or step down voltage levels.

• Switchgear: Used for controlling, protecting, and isolating electrical equipment.

• Motors: Used to convert electrical energy into mechanical energy.

• Control panels: Used for monitoring and controlling various electrical systems.

• Lighting fixtures: Us...read more

Home's law is a principle that states that the current flowing through a conductor is directly proportional to the voltage applied across it.

• Home's law is also known as Ohm's law.

• It is expressed as I = V/R, where I is the current, V is the voltage, and R is the resistance.

• This law is fundamental to the study of electrical circuits and is used to calculate the behavior of circuits.

• For example, if the voltage across a resistor is increased, the current through it will also incr...read more

The number of workmen needed depends on the size and complexity of the traywork, cable vault, and piperack.

• The number of workmen needed for a 100km traywork in 20 days will vary based on factors such as terrain, weather conditions, and equipment availability.

• For a cable vault, the number of workmen required will depend on the size of the vault, the type of cables being installed, and any specific safety regulations that need to be followed.

• In the case of a piperack, the numbe...read more

Transistors are electronic devices used to amplify or switch electronic signals and power. They are essential components in various applications.

• Amplification of weak signals in audio and radio frequency systems

• Switching and control of electronic circuits in computers and digital devices

• Power regulation and control in power supplies and motor control systems

• Signal processing and amplification in communication systems

• Memory storage and logic operations in integrated circuits

• Vo...read more

The measurement of current and voltage is crucial for smart meter projects. Different types of relays are used for protection and load switching in energy meters. Type tests are conducted at CPRI/ERDA for product testing.

• Measurement of current and voltage is done using sensors and sampling techniques in smart meter projects.

• Relays used in energy meters include protection relays and load switches.

• Type tests are conducted at CPRI/ERDA to ensure the quality and performance of th...read more

Questions related to SLD, transformer, DG, interlocking, PM, reports, and SAP knowledge for Electrical Engineer position.

• SLD of power flow in current company

• Ratings of transformer and DG

• Interlocking for a Circuit breaker with SLD

• Checklist of DG i.e types of checks used for DG

• Preventive maintenance of DG

• PM of a motor

• Types of reports/logbook made

• SAP knowledge

The OLTC (On-Load Tap Changer) in a transformer is typically connected to the high voltage side.

• OLTC is connected to the high voltage winding of the transformer

• It allows for tap changing while the transformer is energized

• The low voltage side remains fixed while the high voltage side can be adjusted

Answering questions related to transformer tests, BDB value, relay types, pole types, and conductor ground clearance in 33kv.

• Transformer tests include insulation resistance, turns ratio, and polarity tests.

• BDB value refers to the breakdown voltage of insulating oil.

• Types of relays include overcurrent, differential, and distance relays.

• Types of poles used in 33kv include wooden, steel, and concrete poles.

• Conductor ground clearance is determined by the voltage level and environ...read more

Norton representation is preferred when the load impedance is known and fixed.

• Norton representation is preferred when the load impedance is known and fixed, as it simplifies calculations.

• Thevenin representation is preferred when the load impedance is unknown or variable.

• Norton equivalent circuits are easier to analyze in terms of current flow and power calculations.

• Thevenin equivalent circuits are easier to analyze in terms of voltage and resistance calculations.

The induction motor starting principle is based on the creation of a rotating magnetic field.

• An induction motor starts by applying a voltage to the stator windings, creating a rotating magnetic field.

• The rotating magnetic field induces currents in the rotor windings, which in turn creates a magnetic field.

• The interaction between the stator and rotor magnetic fields causes the rotor to start rotating.

• Different methods like direct-on-line starting, star-delta starting, and auto...read more

Different methods of resistance measurement and their ranges

• Low resistance measurement: 4-wire Kelvin method, range 0.1 μΩ to 1 Ω

• Medium resistance measurement: 2-wire method, range 1 Ω to 1 MΩ

• High resistance measurement: Megohmmeter method, range 1 MΩ to 10 TΩ

• Other methods include 3-wire method and 4-wire guarded method

• Measurement accuracy depends on the method used and the quality of the equipment