RE: broad band EM noise
Here in San Diego, our HV problem is just the opposite; that is, the noise is low during the long period of dry weather, then, when we get a foggy night, the moisture collects in the dusty coating on the insulators. I believe that the overhead distribution lines in residential areas are about 12KV (not the final distribution leg, which is two wires, each 120 V above ground and 240 V line-to-line). On a quiet and foggy night, you can hear a sound like frying bacon coming from the pole tops. The local power company has a crew which cleans the insulators with a blast of distilled water from a truck-mounted nozzle. The power company is more concerned about lost power and fire hazard than RF noise, but the result is lowered RF noise. Ed :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) > -Original Message- > From: Barry Ma [SMTP:barry...@altavista.com] > Sent: Friday, March 10, 2000 3:24 PM > To: EMC-PSTC > Subject: RE: broad band EM noise > > > The broadband interference from corona and any other high-voltage related > sources indicates the problem of power transmission. Those who detected > and reported it deserve a reward from the power company for helping them > reduce the cost. > > Barry Ma > b...@anritsu.com > -- > From: , on 3/10/00 8:14 AM: > > Corona on high voltage insulators is a known source of broadband > interference. Poor connections can also be a problem. A good wash down of > the insulators may temporarily cure or reduce the corona problem. We were > able to locate bad connections near our OATS using a directional antenna > near the power lines. A persistent complaint to the power company may give > the desired results. > > Richard Woods > > > > > For the largest MP3 index on the Web, go to http://mp3.altavista.com > > > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: jim_bac...@mail.monarch.com > Michael Garretson:pstc_ad...@garretson.org > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: broad band EM noise
Rossi Your friend's problem might be similar to the one our EMC lab had in California during the dry season. We were measuring ambient radiated broadband noise in the .1-200 MHz region that had not been there earlier in the year. We checked building wiring, we replaced some fluorescent light balasts, we looked for corrosion on AC power terminals and ground lugs - no improvement. The noise on the spectrum analyzer looked like a group of lines sweeping across the screen, which would become stationary when the spectrum analyzer trigger was set to LINE. The interference made a buzzing noise on the receiver. The local power company said the noise was caused by dirty power line insulators. The dust and dirt accumulates during dry weather and makes an intermittent conductive path. The high voltage arcs over this poor path, making the characteristic spark-gap emitter noise we were seeing on the spectrum analyzer. The power company came by and washed off the insulators on the power poles, and once they were clean, we did not experience the interference. Hope this helps. BTW, they used special trucks and I believe a non-conductive liquid to do the job. Best regards Tom Cokenias T.N. Cokenias Consulting P.O. Box 1086 El Granada CA 94018 tel 650 726 1263fax 650 726 1252 Rossi Giuseppe wrote: > > Dear collegue > I've got a question to which I'm not able to responde: > A friend of mine is complaining about the EM radiated > (not conducted) noise coming from a electrical generation > power plant ( I do not know the exact translation, hope ^^^ ? > that is anyway clear) He told me that the phenomena > is particulary annoying in case of dry weather and that > there is no noise in case of rain or fog. > > Could you give me any hint or point me toward something to read ? Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: broad band EM noise
Rossi Giuseppe wrote: > > Dear collegue > I've got a question to which I'm not able to responde: > A friend of mine is complaining about the EM radiated > (not conducted) noise coming from a electrical generation > power plant ( I do not know the exact translation, hope ^^^ ? > that is anyway clear) He told me that the phenomena > is particulary annoying in case of dry weather and that > there is no noise in case of rain or fog. > > Could you give me any hint or point me toward something to read ? A power plant radiating ??? What's the nature of the problem? Is he at a place of business or in his home when he sees this problem? Regards, Doug --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: broad band EM noise
The broadband interference from corona and any other high-voltage related sources indicates the problem of power transmission. Those who detected and reported it deserve a reward from the power company for helping them reduce the cost. Barry Ma b...@anritsu.com -- From: , on 3/10/00 8:14 AM: Corona on high voltage insulators is a known source of broadband interference. Poor connections can also be a problem. A good wash down of the insulators may temporarily cure or reduce the corona problem. We were able to locate bad connections near our OATS using a directional antenna near the power lines. A persistent complaint to the power company may give the desired results. Richard Woods For the largest MP3 index on the Web, go to http://mp3.altavista.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: broad band EM noise
Method I used to identify culprit poles was to drive a car along the street with AM radio on, tuned at frequency without a signal. Noise from the radio was much louder near culprit poles. A phone call to the power company with a list of culprit pole numbers led up to the solution. Mirko --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: broad band EM noise
Giuseppe, First, a question. What ill effects (to him or to household appliances) are being caused by this EM noise? Scott Lacey -Original Message- From: Rossi Giuseppe [SMTP:g.ro...@crf.it] Sent: Friday, March 10, 2000 10:19 AM To: 'emc-pstc' Subject:broad band EM noise Dear collegue I've got a question to which I'm not able to responde: A friend of mine is complaining about the EM radiated (not conducted) noise coming from a electrical generation power plant ( I do not know the exact translation , hope that is anyway clear) He told me that the phenomena is particulary annoying in case of dry weather and that there is no noise in case of rain or fog. Could you give me any hint or point me toward something to read ? Thank you Giuseppe Rossi --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: broad band EM noise
Giuseppe, Is it the plant or the distribution cables? Our open area test site was rendered unusable by a dirty insulator on a nearby high voltage power pole. Whenever the weather was dry and windy we had broadband noise from 30 MHz to beyond 400 MHz. We found the culprit pole with a spectrum analyzer, log periodic antenna and a "baseball bat"( actually it was a length of 2x4 lumber used like a bat). When we wacked the culprit pole with the "bat", the noise pattern changed momentarily. There was enough vibration from the wack even though the power pole was concrete and of a substantial thickness to produce the change in pattern. (The power company told us that they preferred that we didn't wack their poles. On the other hand, it got their attention and action.) The power company came out and unwound the high voltage cable and rewound it on the insulators and the noise disappeared. We have not had a problem for a couple of years now. Considering the broadband noise was 20 dB above FCC limits, I am sure this would have interfered with TV and Radio signals in the area. As this was primarily a commercial area, we may have been the only ones bothered by it. This may not be your friend's problem, but I could not help but notice the similarity in the humid conditions compared to the dry conditions. Your friend should try contacting the utility company. They do come out and check things out eventually, at least in Florida they do. Good luck, Don Umbdenstock Sensormatic > -- > From: Rossi Giuseppe[SMTP:g.ro...@crf.it] > Reply To: Rossi Giuseppe > Sent: Friday, March 10, 2000 10:19 AM > To: 'emc-pstc' > Subject: broad band EM noise > > > Dear collegue > I've got a question to which I'm not able to responde: > A friend of mine is complaining about the EM radiated (not conducted) > noise > coming from > a electrical generation power plant ( I do not know the exact translation > , > hope that is anyway clear) > He told me that the phenomena is particulary annoying in case of dry > weather > and that there is no noise > in case of rain or fog. > > Could you give me any hint or point me toward something to read ? > > > Thank you > > Giuseppe Rossi > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: jim_bac...@mail.monarch.com > Michael Garretson:pstc_ad...@garretson.org > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: broad band EM noise
Corona on high voltage insulators is a known source of broadband interference. Poor connections can also be a problem. A good wash down of the insulators may temporarily cure or reduce the corona problem. We were able to locate bad connections near our OATS using a directional antenna near the power lines. A persistent complaint to the power company may give the desired results. Richard Woods -- From: Rossi Giuseppe [SMTP:g.ro...@crf.it] Sent: Friday, March 10, 2000 10:19 AM To: 'emc-pstc' Subject: broad band EM noise Dear collegue I've got a question to which I'm not able to responde: A friend of mine is complaining about the EM radiated (not conducted) noise coming from a electrical generation power plant ( I do not know the exact translation , hope that is anyway clear) He told me that the phenomena is particulary annoying in case of dry weather and that there is no noise in case of rain or fog. Could you give me any hint or point me toward something to read ? Thank you Giuseppe Rossi --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
