10+ L&T Construction Electrical GET Interview Questions and Answers

Torque variation in squirrel cage motors is achieved by changing the rotor resistance.

• Torque in squirrel cage motors can be varied by changing the rotor resistance.

• Increasing the rotor resistance will increase the torque produced by the motor.

• Decreasing the rotor resistance will decrease the torque produced by the motor.

• This method is commonly used in applications where variable torque is required, such as in fans or pumps.

Resistance is the opposition to the flow of electric current, while machines are devices that convert energy from one form to another.

• Resistance is measured in ohms and is caused by the material and dimensions of a conductor.

• Machines include motors, generators, transformers, and other devices that use electrical energy to perform work.

• Resistance can be calculated using Ohm's Law: R = V/I, where R is resistance, V is voltage, and I is current.

Challenges in electrical industry include rapid technological advancements, safety concerns, and skilled labor shortage.

• Rapid technological advancements leading to constant need for upskilling and training

• Safety concerns related to electrical hazards and compliance with regulations

• Skilled labor shortage impacting project timelines and quality of work

• Integration of renewable energy sources and smart grid technologies

Synchronous motor is a type of AC motor where the rotation of the shaft is synchronized with the frequency of the supply current.

• Synchronous motor has a rotor with electromagnets and stator with field windings.

• The rotor rotates at the same speed as the rotating magnetic field produced by the stator.

• It requires DC excitation to create a magnetic field in the rotor.

• Used in applications where constant speed is required, such as in power plants and industrial processes.

Speed and torque variation methods are used in electrical systems to control the performance of motors.

• Speed variation methods include changing the frequency of the power supply or using variable speed drives.

• Torque variation methods involve adjusting the voltage or current supplied to the motor.

• Examples of speed variation methods include VFDs (Variable Frequency Drives) and soft starters.

• Examples of torque variation methods include adjusting the field weakening in DC motors ...read more

Machines operate based on various principles such as electromagnetic, mechanical, thermal, and chemical principles.

• Machines convert one form of energy into another to perform work

• Electromagnetic machines use the principles of electricity and magnetism, like motors and generators

• Mechanical machines use moving parts to transfer and transform energy, like engines and gears

• Thermal machines use heat to generate power, like steam engines

• Chemical machines involve chemical reactions ...read more

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

• Transformers work on the principle of electromagnetic induction

• They have primary and secondary coils wound around a core

• Step-up transformers increase voltage while step-down transformers decrease voltage

• Efficiency of a transformer is determined by its core material and design

M15 ratio is the mix ratio of cement, sand, and aggregate in construction.

• M15 ratio is commonly used in construction for preparing concrete.

• It refers to the mix ratio of 1:2:4, which means 1 part cement, 2 parts sand, and 4 parts aggregate.

• This ratio is suitable for general construction purposes where high strength is not required.

Initial setting time of rhc is the time taken for the cement paste to lose its plasticity and become rigid.

• Initial setting time is typically around 30 minutes for ordinary Portland cement.

• It is influenced by factors such as temperature, water-cement ratio, and type of cement used.

• Testing for initial setting time is done using the Vicat apparatus.