Power Grid Corporation of India Graduate Apprentice Trainee Interview Questions and Answers

Parameters of transmission line include resistance, inductance, capacitance, and conductance.

• Resistance: opposition to the flow of current

• Inductance: ability to store energy in a magnetic field

• Capacitance: ability to store energy in an electric field

• Conductance: ability to conduct electric current

• Examples: coaxial cable, waveguide, twisted pair cable

Hysteresis curve is a graphical representation of the relationship between magnetic field strength and magnetization of a material.

• It shows the lag between the magnetic field and the magnetization of a material.

• It is used to study the magnetic properties of materials.

• It is commonly used in the design of magnetic circuits and devices.

• Examples include transformer cores, magnetic storage devices, and electric motors.

• The s...read more

We use step-up transformers to reduce power loss during transmission by increasing voltage and decreasing current.

• Step-up transformers increase voltage and decrease current, which reduces power loss during transmission.

• This is because power loss is proportional to the square of the current, so reducing current reduces power loss.

• For example, power is transmitted over long distances at high voltages (e.g. 500 kV) to red...read more

Power factor is the ratio of real power to apparent power in an AC circuit.

• Power factor is a measure of how efficiently electrical power is being used.

• It ranges from 0 to 1, with 1 being the most efficient.

• A low power factor can result in higher energy costs and equipment damage.

• Capacitors can be used to improve power factor.

• Power factor is important in industries where large amounts of electrical power are used.

There are several types of dampings in case of vibration, including viscous damping, hysteretic damping, and structural damping.

• Viscous damping: It occurs when a fluid or viscous material is used to dissipate energy and reduce vibration.

• Hysteretic damping: It is caused by the internal friction within a material, which converts mechanical energy into heat.

• Structural damping: It is inherent in the structure itself and is...read more

Induction Motor equivalent circuit consists of stator and rotor circuits with mutual induction.

• The stator circuit includes three-phase winding and a power source.

• The rotor circuit includes rotor winding and a short-circuited conductor.

• The mutual induction between stator and rotor circuits causes the rotor to rotate.

• The equivalent circuit can be represented using a circuit diagram with resistances, inductances, and mutu...read more

B-H curve is a graph that shows the relationship between magnetic field strength and magnetic flux density.

• B-H curve is used to characterize the magnetic properties of a material.

• It is a plot of magnetic flux density (B) versus magnetic field strength (H).

• The slope of the curve at any point is the permeability of the material at that point.

• The curve can be used to determine the saturation point of a material.

• Examples o...read more

A multimeter is an electronic device used to measure voltage, current, and resistance in electrical circuits.

• It can measure AC and DC voltage

• It can measure AC and DC current

• It can measure resistance

• It can also measure other electrical parameters such as capacitance and frequency

• It typically has a digital display for easy reading

• Examples of multimeter brands include Fluke, Klein Tools, and Extech