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Lightning Resistors vs. Corona Effect
Name: Pooja
Status: student
Grade: 9-12
Location: N/A
Country: N/A
Date: 11/16/2005
Question:
What is advantage of lightning resistors over corona effect?
Replies:
I do not clearly understand the meaning of your question, Pooja.
And I am not familiar with lightning resistors.
However, I can offer this:
if one has a lightning rod with no resistor,
any corona effect (weak discharge) is likely to help start a strong
lightning discharge.
The lightning-strike's high current is conducted safely to ground,
but it is surrounding magnetically-induced voltages and currents can still
be dangerous.
If, on the other hand, there is a high-voltage resistor in series with the
rod,
this stabilizes low-current discharges like corona discharge,
and by draining local electric fields in the air
it _might_ prevent local lightning strikes instead of drawing them.
Either way the lightning rod is an advantage;
But with a resistor it might be a more refined advantage.
Are you thinking of the similar phrase "lightning arrestor"?
An electric wire leading into the house is a hazard.
Lightning may strike it outside the house, and be carried on the wire inside,
to where people and electronic property are.
A lightning arrestor is a small box along the wire which diverts this
current to an alternate path to ground.
If the small steady currents due to nearby corona discharge come down the
wire,
it works well to have a strong DC blocking capacitor in series, and a
narrow spark gap shunting to ground.
Of course this only works for radio frequencies which can go through the
small high-voltage capacitor.
So arrestors like this are used commonly on TV antenna cables.
If you do not have an arrestor, the currents from a corona discharge
might damage the input of your TV by gradually applying a high voltage to it.
An arrestor cannot work without a separate wire to ground,
which stays outside the house and is preferably shorter and/or thicker
than the indoor segment of the cable.
Jim Swenson
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Update: June 2012
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