Power Systems Questions and Answers - Skin Effect and Proximity Effect Part-2

1. The overvoltage that occur mainly under converter stations are due to _________
(i) Lightening and switching overvoltage
(ii) Transients produced in conductors
(iii) Overvoltage due to fault clearing
Choose the correct option.
a) (i), (ii), (iii)
b) (ii), (iii)
c) (iii)
d) (i), (ii)

Answer: a
Explanation: All the statements are correct.

2. Insulator capacitance is does not play significant role in HVDC lines
a) True
b) False

Answer: a
Explanation: There is no capacitive current which flows in HVDC link.

3. Which of below factor(s) contribute to the more receptibility to pollution of insulators?
a) Ionic current
b) Uniform voltage
c) Electrostatic voltage
d) Ionic current and Electrostatic voltage

Answer: a
Explanation: The ionic current and the electrostatic voltage that develops contributes towards the receptibility of pollution in insulators

4. More number of insulators are needed in AC line as compared to DC line
a) True
b) False

Answer: b
Explanation: No, DC line need more because of thermal runaway, high unit flashover and contamination.

5. he factors which contribute more to the addition of insulator in HDVC line are ____________
a) high unit flashover
b) contamination
c) thermal runaway
d) high unit flashover, contamination and thermal runaway

Answer: d
Explanation: All the factors add to the insulator addition.

6. What makes porcelein type insulator to be off market?
a) Weight
b) Greater failure rate
c) Self clearing
d) Weight and greater failure rate

Answer: d
Explanation: They have higher probability of fault occurrence and possess larger weight.

7.Most industrially accepted insulators used in HVDC is/are ___________
a) high resistance toughened glass type
b) porcelein type
c) silicon rubber composite type
d) all of the mentioned

Answer: a
Explanation: HRTG is mostly accepted.

8. What is the major problem in current interruption in DC circuit?
a) No natural zero current
b) Extra energy stored in circuit
c) High flashover
d) All of the mentioned

Answer: a
Explanation: There is no natural zero current in DC circuit which poses problem.

9. A two conductor DC line is more reliable than a three conductor AC line.
a) True
b) False

Answer: a
Explanation: A two conductor DC can always find path through earth or sea than AC system.

10. Stunt capacitors are installed on ____ and smoothing reactor is installed in ____ in TL.
a) AC side, DC side
b) DC side, DC side
c) AC side, AC side
d) DC side, AC side

Answer: a
Explanation: Shunt capacitors are connected at dc side while inductor at ac.