17. Corona is
- partial breakdown of air
- complete breakdown of air
- sparking between lines
- none of these
18. Higher the frequency, _____________.
- Lower the corona loss.
- Higher is the corona loss.
- Does not affect.
- Depends on the physical conditions.
19. Find the spacing between the conductors a 132 kV 3 phase line with 1.956 cm diameter conductors is built so that corona takes place if the line voltage exceeds 210 kV (RMS). With go = 30 kV/cm.
- 1.213 m
- 2.315 m
- 3.451 m
- 4.256 m
20. The effect of dirt on the surface of the conductor is to _______ irregularity and thereby ________ the break down voltage.
- Decreases, reduces.
- Increases, increases.
- Increases, reduces.
- Decreases, increases.
21. Why are bundled conductors employed?
- Appearance of the transmission line is improved.
- Mechanical stability of the line is improved.
- Improves current carrying capacity.
- Improves the corona performance of the line.
22. In which climate does the chances of occurrence of the corona effect is maximum?
- Dry
- Hot summer
- Winter
- Humid
23. Which harmonics are generated during the corona, which leads to an increase in corona losses?
- Third harmonics
- Fifth harmonics
- Seventh harmonics
- None of these
24. Corona loss can be reduced by using
1. Solid conductor
2. Hollow conductor
3. Bundle conductor
- 1 only
- 1 and 2 only
- 1, 2 and 3 only
- 2 and 3 only
25. A 3-phase transmission line consists of 1 cm radius conductors spaced symmetrically 4 meters apart. Dielectric strength of air is 30 kV/cm. The line voltage for commencing of the corona is
- 132 kV
- 220 kV
- 440 kV
- 200 kV
26. A 3-phase equilateral transmission line has a total corona loss of 53 kW at 106 kV and loss of 98 kW at 110.9 kV. The critical disruptive voltage between the line is
- 66.8 kV
- 22.2 kV
- 53.4 kV
- 32 kV
27. The corona loss on a particular system at 50 Hz is 0.3 kW/Km/phase. What is the corona loss at 60 Hz in kW/Km/phase?
- 0.3
- 0.34
- 0
- can’t be determine
28. Corona occurs in
