jpexg@mit-hermes.ai.mit.edu.AI.MIT.EDU (John Purbrick) (06/24/88)
I was out in the country a few days ago and passed under some high-tension wires. The power lines were emitting a sort of hissing, crackling sound, with no detectable 60Hz component that I could hear. What causes this effect? If it makes a difference, the weather that day was very hot and fairly humid.
todd@uop.edu (Dr. Nethack is back) (06/25/88)
In article <3025@mit-hermes.ai.mit.edu.AI.MIT.EDU>, jpexg@mit-hermes.ai.mit.edu.AI.MIT.EDU (John Purbrick) writes: > I was out in the country a few days ago and passed under some high-tension > wires. The power lines were emitting a sort of hissing, crackling sound, > with no detectable 60Hz component that I could hear. What causes this effect? > If it makes a difference, the weather that day was very hot and fairly humid. I live in the country, and there are some pretty beefy lines nearby.. they make all kinds of noise not relevant to 60Hz. The interesting thing is, it is periodic in nature, and has components that insects can hear before I can. (I.e. the crickets will stop chirping just prior to the noises that I hear...by say 1.5-2.5 seconds) I always wondered about long runs of wire and longwave radio waves, and the earth's electromagnetic fields. --- ARPA cogent!uop!todd@lll-winken.arpa BITNET ucdavis!uop!todd@ucbvax.BITNET Or something like that UUCP ucbvax!ucdavis!uop!todd anyway... UUNET uop!todd@uunet.uu.net
proctor@ingr.UUCP (John Proctor) (06/27/88)
In article <3025@mit-hermes.ai.mit.edu.AI.MIT.EDU>, jpexg@mit-hermes.ai.mit.edu.AI.MIT.EDU (John Purbrick) writes: > I was out in the country a few days ago and passed under some high-tension > wires. The power lines were emitting a sort of hissing, crackling sound, > with no detectable 60Hz component that I could hear. What causes this effect? > If it makes a difference, the weather that day was very hot and fairly humid. What you heard is corona discharge. The same principle applies to electrostatic discharge from any conductor. Dirt, temperature, humidity all come into play in determining how severe the problem is. It will generate broad spectrum RF noise from the am band up beyond 30 MHz. If it was severe let the power company know they might be interested, but not usually. John D. Proctor | Usenet: {ihnp4,uunet}!ingr!jdp!proctor Intergraph Corp. | ARPAnet: uu.net.uunet@ingr!jdp!proctor | US Post: 1 Madison Industrial Park Usual Disclaimers Apply | Huntsville, AL 35807-4201 A foolish consistency is the hobgoblin of little minds, adored by little statesmen and philosophers and divines. "Self Reliance" by Ralph Waldo Emerson
rzh@lll-lcc.aRpA (Roger Hanscom) (06/29/88)
>In article <3025@mit-hermes.ai.mit.edu.AI.MIT.EDU>, jpexg@mit-hermes.ai.mit.edu.AI.MIT.EDU (John Purbrick) writes: >> I was out in the country a few days ago and passed under some high-tension >> wires. The power lines were emitting a sort of hissing, crackling sound, >> with no detectable 60Hz component that I could hear. What causes this effect? >> If it makes a difference, the weather that day was very hot and fairly humid. > >What you heard is corona discharge. The same principle applies to >electrostatic discharge from any conductor. Dirt, temperature, humidity ^^^^^^^^ >all come into play in determining how severe the problem is. It will I work near a **VERY** large DC power supply. The climate here is quite dry, and the power company's overhead lines coming into it crackle and buzz even on the hottest (and driest) of days. But when the humidity goes up (like one of those foggy, winter days), the thing goes wild!! It appears that humidity causes the bulk of the phenomenon. .......................................... ARPA: rzh%freedom.llnl.gov@lll-lcc.llnl.gov