30+ Online Power System Interview Questions

Power System Interview Questions

Power System Interview Questions

1. What is the Power plant or Power Station?

The age, dissemination, and transmission framework together establish a system called as Power plant. The power plant utilizes the type of vitality, for example, coal, diesel and changes over it into electrical vitality. A case of the power framework is a lattice that provisions capacity to the next framework.

2. What do you mean by the zone of protection?

The security is given in the framework to ensure every single component of the power framework. On the off chance that any blame happens in the framework, at that point the transfers related with it trip all the electrical switch so the defective component gets expelled from the power framework. This Security gave to the framework is known as the 'Zone of insurance'.
What is the difference between the Transmission line and distribution line?
The primary work of transmission line and dispersion line is to exchange control starting with one spot then onto the next however the contrast among transmission and dissemination line depends on the elements like the kind of stage, the conveyance line in light of the fact that the wire for transmission line is thick and for circulation line is slight, the transmission line requires three stage supply for conveying power and appropriation line requires single stage supply for conveying power.

3. What are the common sources of energy?

The common sources of energy are:
  • Sun.
  • Water.
  • Waterhead.
  • Fuel.
  • Nuclear Energy.

4. What is a Relay?

The Relay is an automatic device that senses the abnormal condition of the electrical circuit and closes its contact.

5. How many types of Protection relays are there based on the Characteristic?

On the basis of a characteristic, protection relays can be categorized as follows:
  • Definite time relays.
  • IDMT (Inverse time relays with definite minimum time).
  • Instantaneous relays.
  • IDMT with inst.
  • Stepped Characteristic relays.
  • Programmed Characteristic relays.
  • Voltage Restraint overcurrent relays.

6. What is meant by Reset level of the Relay?

The value of current or voltage below which the relay opens it contact is called the reset level of the relay.

7. What are the internal and external faults?

Internal faults are the faults that occur inside the zone and external faults are the faults that occur outside the zone of protection.

8. How many types of faults are there in 3 phase power system?

The faults that occur in the three-phase power system are as follows:
  • Single line to ground (LG) fault
  • Line to line (LL) fault
  • Double line to ground (LLG) fault
  • Three Phase short circuit (LLL) fault
  • Three phase to ground (LLLG) fault

9. What do you mean by reach and reach the point of the relay?

The reach point is the farthest point from the relay which is still inside the zone of protection and reach is the distance between the reach point and relay.

10. Why does the adjacent zone of protection overlap?

Adjoining zone of assurance cover provided that we don't cover then some segment of the power framework will be forgotten unprotected.

11. What is Electrical Grounding?

Electrical establishing or only establishing is a security measure used to avoid individuals inadvertently interacting with the dangerous electrical flaws.

12. What is Electrical Earthing?

Electrical earthing is a process of transferring the immediate discharge of the electrical energy directly to the earth by the help of low resistance wire.

13. How many types of electrical earthing are there?

Electrical earthing is of two types:
  • Neutral Earthing.
  • Equipment Earthing.

14. What is the difference between Electrical earthing and Electrical grounding?

The distinction between electrical earthing and electrical establishing is that in establishing the flow conveying part is associated with the ground, though in earthing the non-flow conveying part is associated with the ground. Establishing does not have zero potential but rather earthing has zero potential.

15. What is the importance of earthing?

Earthing is critical on account of the given beneath reasons: 
  • Earthing shields the individual from the short out current. 
  • Earthing gives the most effortless way of stream for short out current at the season of protection disappointment. 
  • Earthing shields the people and contraption from the high voltage floods and lightning release.

16. What is meant by Sag?

'Sag' is the difference in level between the points of support and the lowest point on the conductor.

17. What is Corona?

'Corona' is the phenomenon of violet glow, hissing noise, and production of ozone gas in an overhead transmission line.

18. How do you select the pickup value of the relay?

The pickup estimation of the transfer ought to be more than the most extreme burden and it ought to permit the ordinary burden just as the specific level of over-burden to be provided. The transfer should be sufficiently delicate to react to the littlest blame, thusly, the pickup esteem ought to be not exactly the littlest blame current.

19. What is the difference between a fuse and a breaker?

The distinction among Fuse and an electrical switch is that meld deals with the standard of the warm and electrical properties of the leading materials, while the electrical switch chips away at the rule of electromagnetism and exchanging guideline. We can utilize the wires just once however circuit breakers can be utilized a lot more occasions, and the breaking limit of the wire is low as contrasted and the electrical switch.

20. What is the difference between the relay and the circuit breaker?

The distinction between the transfer and the electrical switch is that hand-off is an exchanging gadget that gives the flag to the electrical switch in the event of blame event, while electrical switch breaks the circuit consequently when gets the flag.

21. What is the difference between resistance grounding system and resistance earthing system?

In opposition establishing, at least one obstruction is associated with the nonpartisan of the framework. Opposition winding limits the blame current and shields the framework from transient overvoltages. The arcing ground chance is diminished by the opposition establishing and allows the ground blame insurance, while obstruction earthing framework is given in electric hardware to shield the gear from the event of the blame in the framework.

22. What is Primary and Backup protection?

Essential insurance otherwise called fundamental assurance is the primary line of security which gives brisk acting and clearing of the blame inside the limit of the components it ensures. In the electrical establishment, the essential insurance is given to each area. Though the reinforcement security gives the reinforcement to the essential or fundamental assurance at whatever point it flops in task and cut out for fix. For the best possible working of the electrical framework back up insurance is basic.

23. What is meant by Bus Bar Protection?

At the point when the blame happens on the transport bar, at that point the entire of the supply gets interfered, and every one of the feeders are disengaged for this situation Busbar security is given to the framework to dispense with the event of these deficiencies. For evacuating the flaws the whole circuits associating the broken segment should be open.

24. How many types of fault occur in a 3-phase power system?

Electrical faults are the deviation of voltage and current from normal values. There are two types of faults that occur in a three-phase system.
  • Symmetrical faults.
  • Unsymmetrical faults

25. What are the effects of Electrical Faults?

The effects of electrical faults are as follows:
  • Overcurrent flow- During fault occurrence high current flows in the system and which leads to tripping of relays, damaging insulation and components of the equipment.
  • The danger to operating personnel- Fault can also affect the individual working there, and severity of the fault depends upon the voltage and current at the point of fault.
  • Loss of equipment- Heavy current due to short circuit faults result in the burning of equipment completely which leads to improper working of equipment or device.
  • Disturbed interconnected active circuits- During the occurrence of fault the active, connected components of the system also get disturbed.

26. Give some example of fault limiting devices?

Some examples of fault limiting devices are as follows:
Circuit Breaker- It is a device which works in normal condition and breaks when an abnormal condition occurs.
Fuse- A fuse is a thin wire enclosed in a casing or glass which connects two metal parts. It is used as a primary protection device.
Relay- It is a condition based operating switch which opens its contact when an abnormal condition occurs.
Lighting power protection devices- These are the devices that are used to protect the system from surge voltages or lighting like- lightning arrestors and grounding devices.

27. What is Skin Effect?

The propensity of a rotating electric flow (A.C) to get conveyed inside a transmitter to such an extent that the flow thickness winds up biggest close to the outside of the channel, and diminishes with more prominent profundity in the conduit, is called as "Skin Effect."

28. What is a Slack bus?

A slack transport otherwise called reference transport or swing transport adjusts the dynamic and receptive intensity of the framework. The slack transport fills in as rakish reference for every one of the transports in the framework.