Nuclear Power Corporation of India Electrical Engineer Interview Questions and Answers

A transformer is an electrical device that transfers electrical energy from one circuit to another through electromagnetic induction.

• Transformers work on the principle of electromagnetic induction

• They have two coils, primary and secondary, wound around a common magnetic core

• When an alternating current flows through the primary coil, it creates a magnetic field which induces a voltage in the secondary coil

• The voltage in...read more

VCB, SF6, CT, PT, LA are all electrical equipment used in power systems.

• VCB stands for Vacuum Circuit Breaker and is used for switching and protection of electrical power systems.

• SF6 is a gas used as an insulating medium in high voltage electrical equipment such as circuit breakers, switchgear, and transformers.

• CT stands for Current Transformer and is used to measure electrical current in power systems.

• PT stands for Po...read more

Copper and aluminum are commonly used conductors in transmission.

• Copper is an excellent conductor due to its high electrical conductivity.

• Aluminum is also widely used as it is lightweight and cost-effective.

• Other conductors like silver and gold are rarely used due to their high cost.

• Copper-clad steel conductors are used in specific applications where strength is required.

Different types of tests related to transformers include routine tests, type tests, and special tests.

• Routine tests are performed on every transformer and include measurement of winding resistance, insulation resistance, and voltage ratio.

• Type tests are performed on a sample transformer to verify its design and include temperature rise test, impulse test, and short-circuit test.

• Special tests are performed on transforme...read more

Different types of faults refer to the various abnormalities that can occur in an electrical system.

• Short circuit fault

• Open circuit fault

• Ground fault

• Overvoltage fault

• Undervoltage fault

• Overcurrent fault

• Undercurrent fault

Relays are switches that open and close circuits electromechanically or electronically. There are various types of relays.

• Electromechanical relays

• Solid-state relays

• Reed relays

• Polarized relays

• Time-delay relays

• Overload protection relays

• Mercury-wetted relays

• Latching relays

• Machine tool relays

• Thermal relays