1. O/H TRANSMISSION
1.
What is corona phenomenon? When does it occur?
Corona is a type of
electrical discharge at the surface of conductors at high voltage because of
voltage stress, it occurs at foul weather, depends on pressure, temperature,
humidity, pollution level, in air and condition of conductor surface.
2.
What are acceptable corona losses in foul
weather?
5 KW/KM.
3.
How does lightning arrestor work?
Lightning arrestors employ
some form of non linear type of resistance like thyrite or matrosil whose
resistance decreas3es rapidly with increase of applied voltage. But as soon as
energy has been dissipated resistance is restored to a high value which suppresses
the arc across the gap effectively when line voltage returns to normal.
4.
What are the points to be checked when carrying
out inspection of O/H lines?
a)
Frequency weekly/monthly depending in location
b)
Check points non growth of trees, birds’, nests,
cracks of insulators, faulty line regulation structure for mechanical
defect-corrosion.
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