Power Systems Subcategories

Telecommunication Network Management Tmn

Medium Transmission Line

Which of the following is correct operating voltage range for medium transmission lines.

A. More than 765 kv
B. More than 400 kv
C. More than 20 kv
D. More than 132 kv

Explanation: Transmission lines having length more than 80 Km and less than 200 Km, operating voltage between 20 KV and 100 KV fall in the category of medium transmission lines.

What is the value of the charging current flowing to earth in medium transmission line.

A. Very high
B. Medium
C. Negligible
D. No capacitance

Explanation: Owing to appreciable length and voltage of the line the charging current is appreciable in medium transmission lines. Also the capacitance effect cannot be ignored in medium transmission lines.

Performance of short transmission lines depends on which of the following?

A. Resistance and capacitance
B. Resistance and inductance
C. Inductance and capacitance
D. Resistance, inductance and capacitance

Explanation: Medium transmission lines have enough value of resistance and inductance. Length and operating voltage of the medium transmission lines are sufficiently large to cause unavoidable charging current and therefore capacitance effect can not be ignored. Hence, performance of Medium transmission lines depends on R, L and C.

Performance analysis of medium transmission line is done ________

A. By reactance diagram
B. By symmetrical component analysis method
C. By neglecting line inductance
D. On per phase basis

Explanation: Performance analysis of balance transmission line is done only. And is done on per phase basis. No symmetrical component method or reactance diagram method is required for performance analysis.

What is the value of shunt capacitance of medium transmission line?

A. Very high
B. Medium
C. Zero
D. Negligable

Explanation: Length and operating voltage of the medium transmission lines are sufficiently large to cause unavoidable charging current and therefore capacitance effect can not be ignored. Capacitance effect in medium transmission line is less than that in long transmission line.

In medium transmission line the reciving end voltage may be greater than sending end voltage due to Ferranti effect.

A. True
B. False
C.
D.

Explanation: Ferranti effect happens when capacitance effect in medium or long transmission lines becomes greater than inductance effect. This happens during low or no load period.

Series inductance and series resistance of medium transmission lines are taken as:

A. Distributed and lumped
B. Lumped and distributed
C. Distributed
D. Lumped

Explanation: The series inductance and resistance of medium transmission lines are taken as lumped. This makes the performance analysis easier.

Which of the following is like equivalent circuit of medium transmission line?

A. Series rlc circuit
B. Rlc circuit in pie form
C. Series rl circuit
D. Parallel rl circuit

Explanation: Medium transmission lines have considerable amount of inductance, resistance and shunt capacitance. Medium transmission lines are represented as either pie form or as T form.

In medium transmission lines shunt capacitances are considered as lumped.

A. True
B. False
C.
D.

Explanation: In case of medium transmission lines the charging current is unavoidable but less than that in long transmission lines. So it does not cause much error in calculations if shunt capacitances are taken as lumped.