100+ Senior Electrical Engineer Interview Questions and Answers

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

OC and SC tests are conducted on transformers to determine their efficiency and performance under different load conditions.

• OC test (Open Circuit test) is conducted to determine the no-load loss and magnetizing impedance of the transformer.

• SC test (Short Circuit test) is conducted to determine the full-load copper loss and equivalent resistance of the transformer.

• Both tests help in evaluating the efficiency and voltage regulation of the transformer.

• Results from these tests ar...read more

Electrical protection measures for alternators

• Overcurrent protection: Protects against excessive current flow

• Overvoltage protection: Prevents damage from high voltage

• Underfrequency protection: Guards against low frequency operation

• Overtemperature protection: Prevents overheating of the alternator

• Reverse power protection: Protects against power flowing back into the alternator

• Earth fault protection: Detects and isolates faults to ground

• Short circuit protection: Safeguards agai...read more

Effective supervision at site can be achieved through clear communication, regular site visits, and setting clear expectations.

• Establish clear communication channels with site personnel

• Regularly visit the site to ensure work is progressing as planned

• Set clear expectations for quality, safety, and timelines

• Provide adequate training and resources to site personnel

• Encourage open communication and feedback from site personnel

• Address any issues or concerns promptly and fairly

There are three main types of testing for isolators: mechanical testing, electrical testing, and functional testing.

• Mechanical testing involves checking the physical components of the isolator such as the contacts, insulators, and operating mechanism.

• Electrical testing includes measuring the insulation resistance, contact resistance, and dielectric strength of the isolator.

• Functional testing verifies that the isolator operates correctly under load conditions and isolates the ...read more

ABB DCS is a distributed control system used in industrial automation, with various cards and servers for operation.

• ABB DCS stands for ABB Distributed Control System, used in industries for automation.

• The system consists of various cards for different functions such as input/output, communication, etc.

• Servers are used to host the software and manage the communication between different components of the system.

• Example: ABB 800xA is a popular DCS system used in industries.

• Examp...read more

Load calculations involve determining the amount of power required for a single or three phase electrical supply.

• For single phase, load is calculated using the formula P=VI, where P is power, V is voltage, and I is current.

• For three phase, load is calculated using the formula P=√3*V*I*cos(θ), where θ is the phase angle between voltage and current.

• Load calculations are important for determining the appropriate size of electrical equipment and ensuring safety.

• Examples of equipm...read more

I have 8 years of experience in the solar field.

• I have worked on multiple solar projects, including residential and commercial installations.

• I have experience with solar panel design, installation, and maintenance.

• I have knowledge of solar inverters, batteries, and monitoring systems.

• I have conducted feasibility studies and energy audits for solar projects.

• I have kept up-to-date with the latest advancements in solar technology.

Panel installation involves setting up electrical panels for power distribution and control in various applications.

• Identify the location for panel installation, ensuring accessibility and compliance with local codes.

• Mount the panel securely to a wall or structure, using appropriate fasteners.

• Connect incoming power supply lines to the panel's main bus bars.

• Install circuit breakers or fuses in designated slots for circuit protection.

• Label all circuits clearly for easy identifi...read more

VFDs (Variable Frequency Drives) control the speed of AC motors by varying the frequency and voltage of the power supplied to the motor.

• VFDs use power electronics to convert fixed frequency and voltage AC power to variable frequency and voltage power.

• They adjust the motor speed by changing the frequency of the power supplied to the motor.

• VFDs can be controlled through various methods such as analog control, digital control, and network communication.

• Analog control involves us...read more

Types of breakers include circuit breakers, fuse breakers, and earth leakage circuit breakers.

• Circuit breakers are designed to protect electrical circuits from damage caused by overload or short circuit.

• Fuse breakers use a fuse to interrupt the circuit when an overload occurs.

• Earth leakage circuit breakers detect small stray voltages and disconnect the power to prevent electric shock.

• Other types include thermal-magnetic breakers, residual-current devices, and miniature circui...read more

Various standards are used in electrical design depending on the country, industry, and application.

• National Electrical Code (NEC) is used in the United States

• International Electrotechnical Commission (IEC) standards are used globally

• In the automotive industry, ISO 26262 is used for functional safety

• In the aerospace industry, DO-254 is used for airborne electronic hardware

• Standards are also specific to certain applications such as medical devices (IEC 60601) and hazardous loc...read more

The full load current of a 1250 kVA, 11 kV transformer can be calculated using the formula: Full Load Current (A) = kVA / (1.732 x kV)

• The full load current is the current drawn by the transformer when it is operating at its maximum rated power.

• The formula for calculating full load current is: Full Load Current (A) = kVA / (1.732 x kV)

• In this case, the kVA is 1250 and the kV is 11, so the full load current can be calculated as follows:

• Full Load Current (A) = 1250 / (1.732 x 11...read more

Various cable types are used in electrical engineering, including power, control, and communication cables, each serving specific purposes.

• Power cables: Used for transmitting electrical power, e.g., XLPE cables for high voltage.

• Control cables: Used for control circuits, e.g., multi-core cables for automation systems.

• Communication cables: Used for data transmission, e.g., Ethernet cables for networking.

• Instrumentation cables: Used for connecting instruments, e.g., shielded cab...read more

Handled projects with power capacity up to 500 MW

• Managed electrical design and installation for power plants with capacity up to 500 MW

• Oversaw testing and commissioning of electrical systems for large-scale industrial projects

• Implemented energy-efficient solutions to optimize power usage and reduce costs

• Collaborated with cross-functional teams to ensure project timelines and budgets were met

The previous plant SLD (Single Line Diagram) and bus changeover scheme were crucial for the electrical system's operation and maintenance.

• The Single Line Diagram (SLD) provides a simplified overview of the electrical system, showing the connections between various components such as generators, transformers, and loads.

• The bus changeover scheme outlines how power can be transferred between different busbars in case of a fault or maintenance, ensuring continuity of supply.

• Examp...read more

Reduce wastage of materials by implementing efficient inventory management, recycling, and reusing materials.

• Implement an efficient inventory management system to avoid overstocking and understocking of materials

• Recycle materials such as paper, plastic, and metal

• Reuse materials such as packaging materials and scrap metal

• Donate excess materials to local charities or organizations

• Use sustainable materials and products

• Train employees on proper handling and storage of materials

Electrical codes play a crucial role in lighting design, ensuring safety, efficiency, and compliance.

• Electrical codes provide guidelines for the installation, wiring, and operation of lighting systems.

• They specify the minimum requirements for electrical components, such as switches, fixtures, and wiring methods.

• Codes address issues like proper grounding, circuit protection, and voltage limitations to prevent electrical hazards.

• They also cover energy efficiency standards, such...read more

DG is rated in kVA instead of kW because it takes into account the power factor.

• kVA takes into account both active and reactive power

• kW only takes into account active power

• Power factor affects the ratio of active to reactive power

• DGs often have a power factor of less than 1, so kVA is a more accurate rating

• kVA is used for sizing equipment like transformers and switchgear

To install a LT panel, follow these steps: plan the layout, mount the panel, connect the wiring, test the panel, and ensure safety measures.

• Plan the layout of the LT panel installation

• Mount the LT panel securely in the designated location

• Connect the wiring according to the electrical diagram

• Test the LT panel to ensure proper functioning

• Implement safety measures such as grounding and labeling

Mounting heights for electrical equipment vary depending on the specific equipment and its intended use.

• Mounting heights should comply with local building codes and regulations.

• Consider accessibility and maintenance requirements when determining mounting heights.

• Common mounting heights for electrical equipment include 6 feet for switches and outlets, and 18 inches for outlets in kitchens and bathrooms.

Cables are classified into various types based on their construction, application, and insulation materials.

• 1. Power Cables: Used for electrical power transmission (e.g., XLPE cables).

• 2. Control Cables: For control circuits (e.g., PVC insulated control cables).

• 3. Communication Cables: For data transmission (e.g., coaxial cables, fiber optic cables).

• 4. Instrumentation Cables: For connecting instruments (e.g., shielded twisted pair cables).

• 5. Specialty Cables: Designed for spec...read more

Panel board capacity refers to the maximum electrical load it can handle safely and efficiently.

• Common capacities range from 100A to 4000A, depending on application.

• Residential panel boards typically have capacities of 100A or 200A.

• Commercial buildings may use panel boards rated from 400A to 1200A.

• Industrial applications can require panel boards with capacities exceeding 4000A.

• Example: A 200A panel board can support multiple circuits for lighting and outlets in a home.

Cable laying involves the installation of electrical cables for power distribution, communication, or data transmission.

• Cable laying can be done underground, overhead, or underwater depending on the application.

• Proper planning is essential to avoid damage to existing infrastructure.

• Examples include laying power cables for substations or communication cables for internet services.

• Techniques include trenching, directional drilling, and using cable-laying ships for underwater ca...read more

Generator synchronization is the process of connecting a generator to an electrical grid without causing damage to the generator or the grid.

• Ensure the generator voltage, frequency, and phase sequence match the grid

• Adjust the generator's voltage and frequency to match the grid

• Close the circuit breaker to connect the generator to the grid

• Monitor the synchronization process to prevent damage to the generator or the grid

• Use synchronizing equipment such as synchroscope or synchro...read more

Sq mm stands for square millimeter, a unit of area measurement.

• Sq mm is a unit of measurement used to quantify the area of a two-dimensional space.

• It is equal to the area of a square with sides measuring 1 millimeter each.

• Commonly used in engineering and construction for measuring small areas.

• Example: A sheet of paper may have dimensions of 210 mm x 297 mm, which is equivalent to 62370 sq mm.

GIS and AIS are two types of switchgear used in power systems.

• GIS stands for Gas Insulated Switchgear and uses SF6 gas as insulation.

• AIS stands for Air Insulated Switchgear and uses air as insulation.

• GIS is more compact and requires less maintenance than AIS.

• AIS is less expensive than GIS.

• GIS is used in high voltage applications while AIS is used in low to medium voltage applications.

Encoders used in industrial include absolute, incremental, linear, rotary, magnetic, and optical encoders.

• Absolute encoders provide a unique code for each position

• Incremental encoders provide a pulse output for each position change

• Linear encoders measure linear motion

• Rotary encoders measure rotational motion

• Magnetic encoders use a magnetic field to detect position

• Optical encoders use light to detect position

An isolated transformer provides electrical isolation between its primary and secondary windings, enhancing safety and reducing noise.

• Prevents direct electrical connection between input and output, enhancing safety.

• Commonly used in medical equipment to isolate patients from electrical faults.

• Reduces electromagnetic interference (EMI) in sensitive electronic devices.

• Used in power supplies for audio equipment to minimize noise.

• Can be found in industrial applications to protect ...read more

Mesh earthing is a type of grounding system where multiple interconnected conductors are buried in the ground to provide a low impedance path for fault currents.

• Mesh earthing involves burying multiple interconnected conductors in the ground.

• It provides a low impedance path for fault currents to safely dissipate into the ground.

• This type of grounding system is commonly used in electrical installations to protect against electrical faults and lightning strikes.

Wind turbines convert wind energy into electricity through the use of blades that spin a generator.

• Wind turbines capture kinetic energy from the wind

• Blades spin a rotor connected to a generator

• Generator converts mechanical energy into electrical energy

• Electricity is then sent to the grid for distribution

HT daily power consumption is 90kwh.

• HT refers to High Tension power supply.

• The daily power consumption is 90kwh.

• This information can be used to calculate the monthly or yearly power consumption.

• The power consumption may vary depending on the usage and load.

• Efficient use of power can help reduce the consumption and save costs.

PLC stands for Programmable Logic Controller, a digital computer used for automation of industrial processes.

• PLCs are used to control machinery on factory assembly lines.

• They can monitor inputs and outputs to automate tasks.

• Example: A PLC can control the timing of a conveyor belt.

• PLCs are programmable, allowing for flexibility in operations.

• They are widely used in manufacturing, water treatment, and building automation.

Orientation process involves introducing new employees to the company culture, policies, and procedures.

• Orientation typically starts with a welcome message from the company's leadership team.

• New employees are given a tour of the office and introduced to their colleagues.

• They are provided with information about the company's history, mission, and values.

• They are also given an overview of the company's policies and procedures, including HR policies, safety protocols, and IT gui...read more

Encoder is a device that converts motion or position into an electrical signal. Rectifier is a device that converts AC to DC.

• Encoder is used in robotics, automation, and motion control systems.

• Types of encoders include absolute, incremental, linear, and rotary encoders.

• Rectifiers are used in power supplies to convert AC voltage to DC voltage.

• Types of rectifiers include half-wave, full-wave, and bridge rectifiers.

AC drives in steel industries control the speed and torque of motors, improving efficiency and reducing energy consumption.

• AC drives regulate the speed and torque of motors used in various processes in steel industries.

• They help in achieving precise control over the production process, leading to improved efficiency.

• AC drives also help in reducing energy consumption and operational costs in steel plants.

• Examples of applications include controlling the speed of conveyor belts,...read more

Transformers work by transferring electrical energy between two or more circuits through electromagnetic induction.

• Transformers have two coils of wire, known as the primary and secondary coils.

• When an alternating current flows through the primary coil, it creates a changing magnetic field.

• This changing magnetic field induces a voltage in the secondary coil, transferring electrical energy between the two circuits.

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

An isolation transformer separates circuits to prevent direct electrical connection, enhancing safety and reducing noise.

• Provides electrical isolation between input and output, preventing shock hazards.

• Reduces electrical noise and interference, improving signal quality in sensitive equipment.

• Commonly used in medical devices to ensure patient safety.

• Used in audio equipment to minimize hum and noise from power lines.

• Can step up or step down voltage while maintaining isolation.

Cable size can be calculated based on current carrying capacity, voltage drop, and installation conditions.

• Determine the current carrying capacity required for the cable based on the load

• Calculate the voltage drop allowed for the cable based on the distance and voltage rating

• Consider the installation conditions such as ambient temperature and grouping of cables

• Use cable sizing charts or online calculators to find the appropriate cable size

Voltage is the electric potential difference between two points, driving current flow in a circuit.

• Voltage is measured in volts (V).

• It represents the energy per unit charge available to move electrons.

• Example: A standard household outlet in the US provides 120V.

• Higher voltage can lead to greater current flow, given a constant resistance (Ohm's Law).

• Voltage can be AC (alternating current) or DC (direct current).

Choosing the right cable type depends on application, environment, and electrical requirements.

• 1. Power Cables: Used for transmitting electricity; examples include XLPE and PVC cables.

• 2. Control Cables: For control circuits; examples include multi-core cables.

• 3. Data Cables: For data transmission; examples include Ethernet and fiber optic cables.

• 4. Coaxial Cables: Used for radio frequency signals; commonly used in TV and internet connections.

• 5. Specialty Cables: Designed for ...read more

I have extensive maintenance experience in electrical engineering.

• Managed maintenance schedules for electrical equipment and systems

• Performed routine inspections and identified potential issues

• Developed and implemented preventative maintenance plans

• Troubleshot and repaired electrical equipment and systems

• Collaborated with cross-functional teams to ensure timely maintenance and repairs

Load flow study is a method used in electrical engineering to analyze and calculate the flow of power in an electrical network.

• Load flow study helps in determining the steady-state operating conditions of a power system.

• It involves calculating the voltage magnitude and phase angle at each bus in the network.

• The study considers factors like power generation, transmission line losses, and load demand.

• It helps in identifying potential issues such as voltage instability, overload...read more

System studies involve analyzing and evaluating the performance of electrical systems to ensure efficiency and reliability.

• System studies involve analyzing the behavior of electrical systems under different operating conditions.

• They help identify potential issues and optimize the performance of the system.

• Examples of system studies include load flow analysis, short circuit analysis, and protection coordination studies.

132/6.6 kv substation operation involves managing high voltage equipment for power distribution.

• Understanding the operation and maintenance of high voltage equipment such as transformers, circuit breakers, and switchgear

• Ensuring proper grounding and safety measures are in place to prevent electrical hazards

• Monitoring voltage levels, current flow, and overall substation performance

• Troubleshooting and resolving any issues that may arise during operation

• Coordinating with other d...read more