Get premium membership and access questions with answers, video lessons as well as revision papers.
We know that the power W =VI , so for the same power if voltage is increased then
current will decrease. If suppose power required is 500 W and voltage is 250 V then
current I will be equal to 500/250 =2A.
Now if voltage is increased from 250V to 500V and the power required is same then
I = 500/500 =1 A
Now, if the voltage is still increased to say 1000V for the same power then
I = 500/1000 =0.5 A
From the above examples, we see that if the voltage is doubled, the current will be
halved and when it is quadrupled then current is reduced to 1/4th of its initial value.
Thus we conclude that if voltage is increased to n times then the current will be
reduced to 1/nth times for the same power.With the reduction of the current to 1/nth
times, the conductor area will also be reduced to 1/nth times of its original area for
the same current density, Hence less material is required when the voltage is increased
We also know that when the current passes through any conductor, there is loss of
power in that particular conductor according to the relation, I2
R. As the loss is
proportional to the square of the current. So if the current is reduced to ½ value , then
the loss will be reduced to 1/4th its original value. Hence the efficiency of the
transmission line and all others equipments associated with the line will increase and
more power will be available for use.
When current is passing through a conductor there will be a voltage drop according to
the relation V=IR. So, when the current is reduced the drop of the voltage is less in
the line, of course with the same cross sectional area of the conductor.
With the reduction of cross sectional area, considered the main advantage of
transmitting electrical energy at very high voltage viz 132kV , 220kV or even 400kV.
But in case of distribution system such high voltage is dangerous, so distribution
voltage is generally 400/230V.
gregorymasila answered the question on February 20, 2018 at 16:15
- Write short notes on Induction heating:(Solved)
Write short notes on Induction heating:
Date posted: February 20, 2018. Answers (1)
- Discuss methods of laying underground cables.(Solved)
Discuss methods of laying underground cables.
Date posted: February 20, 2018. Answers (1)
- Explain the working of nickel cadmium cells with its merits and demerits over lead acid cell(Solved)
Explain the working of nickel cadmium cells with its merits and demerits over lead acid cell
Date posted: February 20, 2018. Answers (1)
- What are the advantages of high voltage transmission? Give its limitations also.(Solved)
What are the advantages of high voltage transmission? Give its limitations also.
Date posted: February 20, 2018. Answers (1)
- List the advantages of nuclear power plants over conventional thermal power plants.(Solved)
List the advantages of nuclear power plants over conventional thermal power plants.
Date posted: February 20, 2018. Answers (1)
- What is the fundamental difference between thermal and nuclear power plants?(Solved)
What is the fundamental difference between thermal and nuclear power plants?
Date posted: February 20, 2018. Answers (1)
- What are different welding controls used in resistance welding?(Solved)
What are different welding controls used in resistance welding?
Date posted: February 20, 2018. Answers (1)
- With the aid of sketches explain the operation of a four stroke engine(Solved)
With the aid of sketches explain the operation of a four stroke engine.
Date posted: February 16, 2018. Answers (1)
- Name 3 drawing instruments commonly used in technical drawing and define the use of each tool(Solved)
Name 3 drawing instruments commonly used in technical drawing and define the use of each tool
Date posted: January 26, 2018. Answers (1)
- Highlight different methods of water treatment.(Solved)
Highlight different methods of water treatment.
Date posted: January 15, 2018. Answers (1)
- Name any five factors which determine choice of roof structure(Solved)
Name any five factors which determine choice of roof structure.
Date posted: January 1, 2018. Answers (1)
- Give five functional requirements of foundations(Solved)
Give five functional requirements of foundations.
Date posted: January 1, 2018. Answers (1)
- Explain how to test for silt content in sand.(Solved)
Explain how to test for silt content in sand.
Date posted: January 1, 2018. Answers (1)
- List five causes of unsealing of traps(Solved)
List five causes of unsealing of traps.
Date posted: January 1, 2018. Answers (1)
- State 5 principles of a good drainage system.(Solved)
State 5 principles of a good drainage system.
Date posted: January 1, 2018. Answers (1)
- What is critical Mach number in high speed flight?(Solved)
What is critical Mach number in high speed flight?
Date posted: December 29, 2017. Answers (1)
- Give reasons as to why a star delta starter is preferred with induction motor(Solved)
Give reasons as to why a star delta starter is preferred with induction motor
Date posted: November 6, 2017. Answers (1)
- State four advantages of using aluminum tubes over steel when making scaffolds.(Solved)
State four advantages of using aluminum tubes over steel when making scaffolds.
Date posted: October 11, 2017. Answers (1)
- Explain briefly two reasons why blinding is necessary.(Solved)
Explain briefly two reasons why blinding is necessary.
Date posted: October 11, 2017. Answers (1)
- Give four methods of transporting wet concrete to the required position.(Solved)
Give four methods of transporting wet concrete to the required position.
Date posted: October 11, 2017. Answers (1)