This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Medium Transmission Line – 1”.
1. Which of the following transmission line can be considered as medium transmission line?
a) Transmission line of length upto 600 Km
b) Transmission line of length upto 500 Km
c) Transmission line of length upto 200 Km
d) Transmission line of length upto 80 Km
Explanation: The transmission lines having length more than 80 Km and less than 200 Km are considered as medium transmission lines.Their operating voltage is more than short transmission lines but less than long transmission lines.
2. 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.
3. What is the value of the charging current flowing to earth in medium transmission line.
a) Very high
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.
4. 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.
5. 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.
6. What is the value of shunt capacitance of medium transmission line?
a) Very high
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.
7. In medium transmission line the reciving end voltage may be greater than sending end voltage due to Ferranti effect.
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.
8. Series inductance and series resistance of medium transmission lines are taken as:
a) Distributed and Lumped
b) Lumped and Distributed
Explanation: The series inductance and resistance of medium transmission lines are taken as lumped. This makes the performance analysis easier.
9. 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.
10. In medium transmission lines shunt capacitances are considered as lumped.
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.
Sanfoundry Global Education & Learning Series – Power Systems.
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