100+ Senior Electrical Engineer Interview Questions and Answers

We are using IEC 61439 standard for designing the panels and selecting switchgear.

• IEC 61439 is the international standard for low-voltage switchgear and controlgear assemblies

• It provides guidelines for the design, manufacture, and testing of switchgear and controlgear assemblies

• The standard ensures safety, reliability, and performance of the switchgear and controlgear assemblies

• IEC 61439 is widely recognized and accepted in the industry

• Examples of switchgear that comply with ...read more

The thyristor value from gate to cathode in an induction furnace depends on the specific design and requirements of the furnace.

• The thyristor value is determined by the voltage and current ratings required for the induction furnace.

• It is important to select a thyristor with appropriate voltage and current handling capabilities to ensure reliable operation.

• The thyristor value may vary depending on the power rating and frequency of the induction furnace.

• Consulting the furnace's...read more

VFDs control the speed of AC motors by varying the frequency and voltage of the power supplied to the motor.

• VFD stands for Variable Frequency Drive

• Basic components include rectifier, DC bus, inverter, and control system

• Parameters include frequency, voltage, current, and acceleration/deceleration time

• VFDs can improve energy efficiency and reduce wear and tear on motors

• Example: VFDs are commonly used in HVAC systems to control the speed of fans and pumps

Over current protection is for excessive current flow, while earth fault protection is for current leakage to earth.

• Over current protection is used to protect against excessive current flow in a circuit.

• Earth fault protection is used to detect current leakage to earth.

• Over current protection is typically achieved using fuses or circuit breakers.

• Earth fault protection is typically achieved using residual current devices (RCDs) or ground fault circuit interrupters (GFCIs).

• Over ...read more

There are several types of testing performed in transformers.

• Routine testing: performed during manufacturing to ensure the transformer meets specifications.

• Type testing: performed on a sample transformer to verify its design and performance.

• Special testing: performed for specific requirements or conditions, such as temperature rise testing or impulse testing.

• Diagnostic testing: performed to assess the condition of a transformer, including insulation resistance testing and oil...read more

We use various software depending on the type of electrical component being tested.

• We use simulation software like LTSpice and PSpice for circuit analysis.

• For testing microcontrollers, we use software like Keil and MPLAB.

• For power system analysis, we use software like ETAP and PowerWorld.

• We also use software like LabVIEW and MATLAB for data acquisition and analysis.

2 wire and 4 wire communication are methods used for transmitting data or signals between devices.

• 2 wire communication uses a single pair of wires for both transmitting and receiving data.

• 4 wire communication uses two pairs of wires, one for transmitting and one for receiving data.

• 2 wire communication is commonly used in simple applications like telephone lines.

• 4 wire communication is used in more complex applications like Ethernet networks.

• Examples of 2 wire communication pr...read more

Reactive power loss in transformer can be calculated using the formula Q = V^2/X, where V is the voltage and X is the reactance.

• Reactive power loss occurs due to the magnetic field in the transformer

• It is important to calculate reactive power loss to ensure efficient operation of the transformer

• Reactance can be calculated using the formula X = 2πfL, where f is the frequency and L is the inductance

• Reactive power loss can be reduced by using capacitors to compensate for the rea...read more

GIS stands for Geographic Information System. ICT Protection refers to the protection of information and communication technology systems. REF stands for Relay Electronic Fundamentals.

• GIS is a system that captures, stores, analyzes, and presents geographic data.

• ICT Protection involves measures to safeguard information and communication technology systems from unauthorized access, damage, or disruption.

• REF is a branch of electrical engineering that deals with the fundamentals ...read more

The depth of erection of Gi pipe for transformers depends on various factors such as soil conditions, transformer size, and local regulations.

• The depth of the Gi pipe should be sufficient to provide stability and support to the transformer.

• It is important to consider the soil conditions to ensure proper anchoring of the Gi pipe.

• Local regulations may specify minimum depth requirements for the erection of Gi pipe for transformers.

• The size and weight of the transformer should al...read more

Over current in furnace is mainly caused by short circuits or overload.

• Short circuits

• Overload

• Faulty wiring

• Malfunctioning equipment

Various types of protections are used in Powergrid substation to ensure safety and reliability of the system.

• Overcurrent protection

• Under/overvoltage protection

• Differential protection

• Distance protection

• Frequency protection

• Ground fault protection

• Backup protection

• Isolation protection

• Lightning protection

KPIs for spares maintenance and explanation of MTTR and MTBF

• KPIs are key performance indicators used to measure the effectiveness of spares maintenance

• Spares maintenance involves managing and tracking the inventory of spare parts

• MTTR (Mean Time to Repair) measures the average time taken to repair a failed component or system

• MTBF (Mean Time Between Failures) measures the average time between consecutive failures of a component or system

• Maintaining spares involves ensuring an a...read more

Soft starters are preferred over star-delta starters for motor start and run due to their ability to reduce inrush current and provide smoother acceleration.

• Soft starters provide a gradual increase in voltage to the motor, reducing inrush current and mechanical stress on the motor.

• Star-delta starters provide a sudden increase in voltage, resulting in high inrush current and mechanical stress on the motor.

• Soft starters also provide smoother acceleration and deceleration, reduc...read more

Inductance value of motor and pi value of transformer can be found using different methods.

• Inductance value of motor can be found using LCR meter or by measuring the voltage and current waveforms and calculating the inductance using mathematical formulas.

• Pi value of transformer can be found by measuring the open circuit voltage and short circuit current and using the formula Pi = (open circuit voltage / short circuit current) * 2.

• Inductance value of motor and pi value of tran...read more

The current carrying capacity of AB cable refers to the maximum amount of electrical current that the cable can safely carry.

• The current carrying capacity depends on factors such as the cable's size, material, insulation, and ambient temperature.

• It is important to consider the cable's ampacity rating and derating factors for different installation conditions.

• AB cable is typically used for overhead power distribution and its current carrying capacity can vary based on the spec...read more

The question is about types of AC, UPS rating, PAC, and its usage in server rooms.

• There are two types of AC - window and split AC.

• UPS rating is the amount of power that a UPS can supply to connected devices.

• PAC stands for Precision Air Conditioning and is used in server rooms to maintain a constant temperature and humidity level.

• PACs are used in server rooms because they provide better control over temperature and humidity compared to regular ACs.

• UPS rating is important in se...read more

Primary reasons for major breakdowns in machines include lack of maintenance, overheating, wear and tear, and electrical faults.

• Lack of regular maintenance leading to accumulation of dirt and debris

• Overheating due to poor ventilation or excessive workload

• Wear and tear of components over time causing malfunctions

• Electrical faults such as short circuits or power surges

Standard operating procedures for machine maintenance include regular inspections, cleaning, lubrication, and calibration.

• Regularly inspect machines for signs of wear and tear

• Clean machines to remove dust, debris, and other contaminants

• Lubricate moving parts to reduce friction and prevent breakdowns

• Calibrate machines to ensure accurate performance

• Keep detailed records of maintenance activities and schedules

I have extensive knowledge of electrical systems used in highway maintenance, including lighting, traffic signals, and communication systems.

• Experience with designing and implementing electrical systems for highway lighting to ensure safety and visibility for drivers

• Knowledge of traffic signal systems to optimize traffic flow and improve safety at intersections

• Familiarity with communication systems used for monitoring and controlling highway infrastructure, such as CCTV camer...read more

A transformer double pole structure is a configuration that includes two poles in a transformer.

• A transformer double pole structure is used to increase the voltage capacity of a transformer.

• It consists of two separate poles, each with its own primary and secondary windings.

• The primary windings of both poles are connected in parallel, while the secondary windings are connected in series.

• This configuration allows for higher voltage transformation and increased power handling ca...read more

The oil used in power transformers is called transformer oil. It typically contains elements such as carbon, hydrogen, and oxygen.

• Transformer oil is typically mineral oil-based, such as naphthenic or paraffinic oil.

• Elements found in transformer oil include carbon, hydrogen, and oxygen.

• Other elements like sulfur may also be present in transformer oil.

Hazardous classification refers to the categorization of substances or environments based on their potential to cause harm or danger.

• Hazardous classification is used to identify and communicate the level of risk associated with different substances or environments.

• It helps in determining the appropriate safety measures and precautions to be taken.

• Classification criteria include factors such as flammability, explosiveness, toxicity, and reactivity.

• Examples of hazardous classif...read more

Transformers used in furnaces are mainly of two types - power transformers and isolation transformers.

• Power transformers are used to step down the high voltage power supply to a lower voltage suitable for the furnace.

• Isolation transformers are used to isolate the furnace from the power supply to prevent electrical interference.

• Other types of transformers used in furnaces include control transformers and potential transformers.

• Control transformers are used to power the control...read more

Manage subcontractors and stakeholders by clear communication, setting expectations, regular updates, and addressing concerns promptly.

• Establish clear communication channels with subcontractors and stakeholders

• Set clear expectations and goals for the project

• Provide regular updates on project progress and milestones

• Address any concerns or issues promptly to maintain good relationships

• Hold regular meetings to discuss progress, challenges, and next steps

• Ensure all parties are al...read more

Slip ring motor has external connections for rotor winding while 3 phase induction motor has a squirrel cage rotor.

• Slip ring motor has external connections for rotor winding, allowing for external control of rotor circuit.

• 3 phase induction motor has a squirrel cage rotor, which is simpler and more rugged.

• Slip ring motor is used in applications where variable speed control is required, such as cranes and hoists.

• 3 phase induction motor is commonly used in industrial application...read more

Yes, I have experience handling ELV packages independently.

• I have worked on multiple projects where I was solely responsible for the ELV package.

• I am familiar with the design and installation of ELV systems such as fire alarm, CCTV, access control, and PA systems.

• I have experience coordinating with other trades to ensure proper integration of ELV systems.

• I am confident in my ability to handle any challenges that may arise during the ELV package installation process.

Yes, I have installed transformers and panels in various projects.

• I have experience in installing transformers and panels in both commercial and residential projects.

• I am familiar with the wiring and connections required for proper installation.

• I have worked with different types of transformers such as step-up, step-down, and isolation transformers.

• I have also installed various types of panels such as distribution panels, control panels, and switchboards.

• I ensure that all ins...read more

I have extensive experience managing electrical maintenance expenses in various projects.

• Managed budget for electrical maintenance in large commercial buildings

• Implemented cost-saving measures without compromising safety or quality

• Worked closely with vendors to negotiate pricing for maintenance services

• Utilized predictive maintenance techniques to reduce unexpected expenses

• Regularly reviewed and analyzed maintenance expenses to identify areas for improvement

NGR stands for Neutral Grounding Resistor. It limits fault current and protects equipment.

• Limits fault current during ground faults

• Protects equipment from damage

• Improves safety by reducing risk of electric shock

• Commonly used in power distribution systems

• Example: NGR is used in transformer neutral grounding to limit fault current

SF6 circuit breaker is a type of circuit breaker that uses sulfur hexafluoride gas as the insulating and arc extinguishing medium. Testing of power transformers involves various electrical tests to ensure proper functioning.

• SF6 circuit breaker uses SF6 gas for insulation and arc extinguishing

• Testing of power transformers includes insulation resistance test, turns ratio test, and power factor test

• SF6 circuit breakers are commonly used in high voltage applications

• Power transfor...read more

Arc furnaces typically use three-phase transformers, slop ring induction motors are used in cranes for better control, safety guards protect against hazards, and motor plate specifications include important details about the motor.

• Arc furnaces typically use three-phase transformers for power supply and voltage regulation.

• Slop ring induction motors are used in cranes for better control over speed and torque.

• Safety guards are used to protect against hazards such as moving parts...read more

I am currently working on designing and implementing a power distribution system for a large industrial facility.

• Designing power distribution layout for the facility

• Selecting appropriate electrical components and equipment

• Ensuring compliance with safety regulations and standards

• Collaborating with other engineers and stakeholders on the project

Solar capacity and costing depend on specific requirements such as location, energy needs, and system size.

• Solar capacity is measured in kilowatts (kW) and can range from a few kW for residential systems to several MW for commercial or utility-scale systems.

• The cost of solar depends on factors such as the size of the system, location, and available incentives or rebates.

• For example, a 5 kW residential solar system in California may cost around $15,000 after incentives, while ...read more

Parameters and their descriptions used in CNC/VMC machines.

• Feed rate: speed at which the cutting tool moves through the material

• Spindle speed: rotational speed of the spindle

• Depth of cut: amount of material removed in a single pass

• Tool offset: distance between the tool tip and the spindle centerline

• Work offset: distance between the workpiece and the machine reference point

• Tool life: duration of time a tool can be used before it needs to be replaced

• Tool wear: gradual deteriora...read more

Control logic of electrical panel involves designing and implementing the logic for controlling various electrical components.

• Designing the logic for controlling electrical components such as motors, pumps, and valves

• Implementing the control logic using programmable logic controllers (PLCs) or other control systems

• Testing and troubleshooting the control logic to ensure proper operation

• Documenting the control logic for future reference and maintenance

• Ensuring compliance with s...read more

A soft starter panel is an electrical device used to control the starting current of an electric motor.

• It reduces the mechanical stress on the motor during startup.

• It gradually increases the voltage supplied to the motor.

• It can be used to control the speed of the motor.

• It is commonly used in applications where a large amount of power is required to start the motor.

• Examples include pumps, compressors, and conveyor belts.

MCB selection and types of control systems and devices with examples.

• MCB selection depends on the load current and short circuit current rating.

• Types of control systems include open-loop, closed-loop, and feedback control.

• Examples of control devices include sensors, actuators, and programmable logic controllers (PLCs).

A Single Line Diagram (SLD) of a 33/11 kV switchyard shows the layout and connections of electrical equipment.

• Key equipments include transformers, circuit breakers, isolators, busbars, surge arresters, and control panels.

• Transformers step down voltage from 33 kV to 11 kV for distribution.

• Circuit breakers protect the system from overloads and short circuits.

• Isolators are used for isolating equipment for maintenance.

• Busbars distribute power within the switchyard.

• Surge arresters...read more

Electrical operations and maintenance include troubleshooting, repair, and preventive maintenance. Transformer protection involves measures to prevent damage to transformers.

• Electrical operations and maintenance involve troubleshooting and repairing electrical systems, as well as performing preventive maintenance to ensure their proper functioning.

• Preventive maintenance includes tasks such as cleaning, lubricating, and inspecting electrical equipment.

• Transformer protection in...read more

The cable size for a 5 hp motor depends on the voltage and current rating of the motor.

• Cable size is determined by the current rating of the motor

• Voltage rating also plays a role in determining cable size

• For a 5 hp motor, the cable size can range from 10 AWG to 6 AWG depending on the voltage and current rating

• It is important to consult the manufacturer's specifications for the motor to determine the appropriate cable size

Duty cycle of SF6 circuit breaker refers to the ratio of time it can be operated to the total time period.

• Duty cycle is expressed as a percentage

• It is important to ensure that the breaker is not operated beyond its duty cycle

• For example, if the duty cycle is 50%, the breaker can be operated for 30 minutes in an hour

• Exceeding the duty cycle can cause damage to the breaker and reduce its lifespan

Gravels are used in switch yards to provide a stable surface for equipment and to improve drainage.

• Gravels help in reducing the risk of equipment damage due to flooding or standing water.

• They also help in preventing erosion and maintaining the stability of the ground.

• Gravels are easy to install and maintain, making them a cost-effective option for switch yards.

• They allow for better heat dissipation, which is important for electrical equipment.

• Gravels can also help in reducing...read more

Maintenance type refers to the type of maintenance required for electrical equipment and systems.

• There are three main types of maintenance: corrective, preventive, and predictive.

• Corrective maintenance involves fixing equipment after it has failed.

• Preventive maintenance involves regularly scheduled maintenance to prevent equipment failure.

• Predictive maintenance involves using data and analytics to predict when maintenance is needed.

• Implementation of maintenance type depends o...read more

Communication and collaboration are key to handling shift work with colleagues.

• Establish clear communication channels with colleagues to ensure smooth handovers between shifts.

• Maintain open and transparent communication to address any issues or concerns that may arise during shift work.

• Collaborate with colleagues to share workload and support each other during busy periods.

• Utilize technology tools such as shared calendars or messaging apps to stay connected with colleagues ev...read more

Communicate openly, provide support, set clear expectations, offer solutions

• Communicate openly with designers to understand their challenges and concerns

• Provide support and resources to help designers overcome tough times

• Set clear expectations and goals to keep designers focused and motivated

• Offer solutions and brainstorm ideas together to find the best way forward

VFD is a device used to control the speed of an electric motor. LV panels are used to distribute power to various loads.

• VFD works by adjusting the frequency of the power supplied to the motor, which in turn controls its speed.

• LV panels are designed to distribute power to various loads in a safe and efficient manner.

• Design of LV panels involves selecting appropriate components such as circuit breakers, fuses, and contactors based on the load requirements.

• LV panels also need to...read more