Transmission Line Radio Interference (70 MHz to 250 MHz)

[NAZ55]

Looking for some suggestions on possible causes of radio interference on a 230kV line, which would be in the frequency range of 70 to 250 MHz.

 

[dpc]

Loose connections at insulators and corona discharge can be healthy sources of RFI but generally not at frequencies this high. These sources are generally localized and can often be found using a hand-held receiver such as a portable AM radio or VHF hand-held. Better equipment can narrow it down to particular insulators or components. Such as:

http://radareng.azurewebsites.net/

Power-line carrier systems used for meter reading/communications might be another source.

 

[cuky2000]

Beware that most States do not have a requirement for interference at 230 kV and below. Also check if there is any requirement from the Federal Communication Commission, commercial airport or military base in the vecinity of the T. Line.

A good engineering practice suggests typical radio signal to noise ratios above 20 db, and TV signal to noise ratios above 40 db at the edge of the right-of-way in fair weather conditions.

Weather and time of the day impact the noise and interference issues. Limits of 55dbA during the daylight hours and 50 dbA at night are commonly used.

Proper conductor size and corona rings could be used to mitigate any communication interference

 

[HamburgerHelper]

Any interference I have heard of has come from parallel lines using power line carrier. Power line carrier sends a very strong signal that more often than not passes through the faulted section. The power line frequencies I have seen used are designated navel frequencies by the FCC. To avoid interference from one plc system to another through coupling a frequency offset of 1kHz is sometimes use to avoid standing waves.

------------------------------------------------------------------------------------------
If you can't explain it to a six year old, you don't understand it yourself.

 

[HamburgerHelper]

Any interference I have heard of has come from parallel lines using power line carrier. Power line carrier sends a very strong signal that more often than not passes through the faulted section. The power line frequencies I have seen used are designated navel frequencies by the FCC. To avoid interference from one plc system to another through coupling a frequency offset of 1kHz is sometimes use to avoid standing waves. If you talk with a plc vendor, I suspect he will tell you that the pickup is or can be set high enough to avoid outside noise at the used frequencies.

------------------------------------------------------------------------------------------
If you can't explain it to a six year old, you don't understand it yourself.

------------------------------------------------------------------------------------------
If you can't explain it to a six year old, you don't understand it yourself.

 

[dpc]

RFI from power systems existed long before power line carrier systems. Any corona discharge or loose connections can be rich sources. If you've ever listened to AM radio while driving in the country, you'll experience it first hand.

 

[NAZ55]

Thank you for all the responses so far. Very helpful.

Do you all know which standards apply here?

IEEE, ICES, CSA, ANSI, IEC.

Sincerely,
Zeeshan

 

[dpc]

In the US, the FCC is responsible for the radio frequency spectrum but don't expect much. If you are experiencing RFI that you think is caused by a utility, first step would be to talk the utility. You could contact arrl.org. This is the amateur radio organization in the US. They have some help available. If you are a utility trying to track down a source, just hire Radar Engineers or ask for a recommendation. They do this for a living.