Power System1

  1. Which conductors connects the consumer’s terminals to distribution?

    There are different segments in power system transmission and distribution. After the power is transmitted from the generating station, zonal main substation distributes them into different substations through the feeder cable. There are no tapping from the feeder cable. After that the power is distributed among the service mains through the distributor cables. The tappings are taken out from the distributor cables. From the service mains, cable are locally connected with consumers terminals.

  2. An overhead line conductor has an inductance per unit length of L henry. If the entire medium around the conductor is filled with a dielectric material of permittivity ε, then the inductance will be

    Because new inductance = Inductance of conductor(L) / permittivity of the dielectric material (ε).

  3. Air blast circuit breaker is most suitably used in

    Under construction.

  4. Describe the functions of line insulators?

    Under construction.

  5. In low power factor the voltage regulation of a generator will be

    Under construction.

  6. The underground system cannot be operated above which voltage level?

    Actually underground cable system is most suitable for those areas, where the neat and clean distribution is required. Mainly this type of wiring is seen in metro cities. The spaces in between the conductors are quite lesser as compared to overhead cables. So, strong insulation is provided with each cables. And after that, different layer of insulation are provided surrounding those cables. Considering all those things, 66 KV is considered as the highest voltage level for underground cable system.

  7. Overhead lines can be designed for operation up to

    In case of overhead transmission lines, the space in between the conductors are more as compared to underground system. And additionally, air acts like the insulation medium for those cables. As those conductors are clipped at very high position, so the clearance from the ground is also OK for those cables. These all features permits together for transmission of extra high voltage through the overhead cables. So, the huge amount of 400 KV is transmitted via the overhead lines, with suitable cables and pole structures.

  8. Which of the following material is not used for transmission and distribution of electric power?

    Material with high conductivity is used in power system transmission and distribution. Most economical cables are built up with that material, which is best conductor of electricity as well as cheap too. Because the span of transmission lines is quite large, sometime overseas. So, the conductor must be cheap to ensure the economy. And for better conductivity, copper is used. Although all of those metals are used as conductor for transmission system, but aluminum is preferred because this metal have some unique features. It is quite cheap, and the conductivity is very good, and the aluminium wires are mechanically strong.

  9. The usual span with RCC poles are

    The full form of RCC pole is reinforced cement concrete. This type of poles are most suitable for low voltage transmission, like consumer areas.

  10. The corona is affected by which of the following?

    Corona is an phenomenon of transmission lines. The outer portion of transmission lines starts glowing with light violet glow, and a hissing sound is there. The air surrounding the conductors get ionized, and after that this particular phenomenon is observed. If the outer surface of the conductor is rough and irregular, then there is more chances of corona. And this phenomenon is depended upon the size, shape and surface of conductor. This is the reason for which the conductors are chosen as round shaped and smooth.

  11. High voltage transmission line use

    Pin type insulator is suitable for medium voltage range, because the insulation is so designed that it wound be able to handle the medium voltage. There are several parameters like puncture strength etc are associated with line insulators. In case of suspension type insulators, a series of insulator discs are arranged and according to the voltage level, the discs are designed. In fact, addition of discs are also possible for this type of insulators. Therefore, in high voltage transmission, suspension insulators are preferred.

  12. By which of the following system electric power can be transmitted?

    For high voltage transmission overhead system is preferred, because it is quite safer and lot of spaces are there in between two parallel conductors. Underground system is preferred for those areas, where the neat and clean transmission system is required, like different metro cities.

  13. Distribution lines in India generally use

    RCC means reinforced cement concrete. This type of poles are very cheap, and also very easy to construct. Concerete structure is very rigid and no effect of moisture. The distribution poles are provided in many street junctions, roads etc. As per the climate conditions and considering the economy, RCC poles are best suitable option for distribution poles in India.

  14. The square root of the ratio of line impedance and shunt admittance is called

    Under construction.

  15. The phenomenon of rise in voltage at the receiving end of open circuited or lightly loaded line is called

    This phenomenon is seen in long transmission lines. If a large is opened from the line, or if the line is connected with very light load, then the receiving end voltage will be greater then the sending end voltage.

  16. A booster is a

    Under construction.

  17. Transmission line insulators are generally made up of

    The transmission lines are quite long and the insulators required is very high for long transmission lines. So, the insulator must be cheap and easily available. Porcelain shows very good insulation property, even in very high voltage level. A series of porcelain discs, or sometime pin type porcelain insulator is used in transmission lines. Glass is also very good insulator, but handling and other costs are more, therefore porcelain insulators are most widely used.

  18. The distributors for residential areas are

    In domestic areas, the required voltage level is 220 Volt to 230 Volt single phase. A neutral wire also needed to complete the circuit. Line voltages are suitable for industrial applications, but in domestic areas, three phase star connection is most suitable. This connection gives three different phase cables along with a common neutral wire. Each phase carries 230 Volt each, so the phases are distributed among the service mains with the neutral wire. The neutral wire is grounded at the substation via an earthing transformer.

  19. A reactance relay is

    Under construction.

  20. The capacitor switching is easily done with

    Under construction.