Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne 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



Click here to return to the Engineering Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory