L&T Technology Services Senior Electrical Engineer Interview Questions, Process, and Tips

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 contac...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 applicat...read more

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 accept...read more

Explanation of design calculations for selecting busbar size, switchgear, type-2 coordination, and discrimination study.

• Busbar size selection based on current carrying capacity and voltage drop

• Switchgear selection based on fault level and load current

• Type-2 coordination ensures proper operation of protective devices during a fault

• Discrimination study ensures that only the faulty section of the system is isolated during...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 ...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 c

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

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 ...read more