Important Questions of Performance of Transmission Lines :

1. What is the purpose of an overhead transmission line ? How are these lines classified ?

2. Discuss the terms voltage regulation and transmission efficiency as applied to transmission line.

3. Deduce an expression for voltage regulation of a short transmission line, giving the vector diagram.

4. What is the effect of load power factor on regulation and efficiency of a transmission line ?

5. What do you understand by medium transmission lines ? How capacitance effects are taken into account

in such lines ?

6. Show how regulation and transmission efficiency are determined for medium lines using

(i) end condensor method

(ii) nominal T method

(iii) nominal π method

Illustrate your answer with suitable vector diagrams.

7. What do you understand by long transmission lines ? How capacitance effects are taken into account in such lines?

8. Using rigorous method, derive expressions for sending end voltage and current for a long transmission line.

9. What do you understand by generalized circuit constants of a transmission line? What is their importance?

10. Evaluate the generalized circuit constants for

(i) short transmission line

(ii) medium line — nominal T method

(iii) medium line — nominal π method

11. What is the justification in neglecting line capacitance in short transmission lines ?

12. What are the drawbacks of localized capacitance methods ?

13. A long transmission line is open circuited at the receiving end. Will there be any current in the line at the sending end ? Explain your answer.

14. Why is leakage conductance negligible in overhead lines ? What about underground system ?

15. Why do we analyze a 3-phase transmission line on single phase basis ?