electrical system specialist Interview Questions and Answers

1. What is the difference between AC and DC current?

   • Answer: AC (Alternating Current) changes direction periodically, while DC (Direct Current) flows in only one direction. AC is more easily transformed to higher or lower voltages, making it suitable for long-distance transmission. DC is typically used in smaller scale applications and electronics.

2. Explain Ohm's Law.

   • Answer: Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. Mathematically, it's represented as V = IR, where V is voltage, I is current, and R is resistance.

3. What is a transformer and how does it work?

   • Answer: A transformer is a passive electrical device that transfers electrical energy from one circuit to another through electromagnetic induction. It typically consists of two coils of wire wound around a common magnetic core. A changing current in the primary coil creates a changing magnetic field, which induces a voltage in the secondary coil. The ratio of the number of turns in each coil determines the voltage transformation.

4. What are the different types of electrical motors?

   • Answer: There are many types, including DC motors (series, shunt, compound), AC motors (induction motors – squirrel cage and wound rotor; synchronous motors), and stepper motors, each with its own characteristics and applications.

5. Explain the concept of grounding.

   • Answer: Grounding provides a low-resistance path for fault currents to flow to the earth, protecting equipment and personnel from electrical shocks. It also helps stabilize voltage levels and reduce the risk of electrical hazards.

6. What is a circuit breaker and how does it work?

   • Answer: A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. It uses a mechanism to interrupt the current flow when a fault is detected.

7. What are the safety precautions when working with high voltage systems?

   • Answer: Always use appropriate personal protective equipment (PPE), including insulated gloves, safety glasses, and arc flash suits. Lockout/Tagout procedures must be followed before working on any energized equipment. Proper training and certification are essential.

8. What is the difference between a fuse and a circuit breaker?

   • Answer: Both protect circuits from overcurrent, but fuses are one-time use devices that melt and require replacement, while circuit breakers can be reset and reused.

9. Explain the concept of power factor.

   • Answer: Power factor is the ratio of real power (kW) to apparent power (kVA) in an AC circuit. It represents the efficiency of power utilization. A lower power factor indicates more reactive power, leading to higher energy costs and potential equipment issues.

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