Power Line Carrier Technology

The key difference between FreeState’s AMI system and other systems used by many electric utilities is that FreeState’s system uses Power Line Carrier (PLC) technology to transmit meter reading data.  This means the system uses the utility’s power lines to transmit the meter reading data. FreeState’s meter data is not transmitted via radio frequency waves in the air. 

Below is some information that that was prepared by the manufacturer of FreeState’s advanced metering infrastructure (AMI) or “smart meter” system.  This information presents information regarding the electromagnetic field (EMF) level emitted by the metering equipment.  

All electrical devices create some level of EMF.  This is due to the fact that for any electrical device to operate, it requires the presence of an electric field and a magnetic field. Electric fields are created by voltage.  Magnetic fields are created by electrical current flow.  Electric fields are typically measured in volts per meters (V/m).  Magnetic fields are typically measured in units of Amperes per meter, gauss (G), or Teslas (T). Physics dictates that these fields be present for any electrical device (digital or analog) to produce work.

FreeState’s new AMI system does produce low-frequency EMF similar to any household electric device.  The communication signals produced by the AMI system are in relatively narrow frequency bands between 3 Hz to 3000 Hz and are transmitted via the utility power lines.  All electric utilities in North America generate electricity at a frequency of 60 Hz.  These frequencies fall into the Extremely Low Frequency (ELF) portion of the total frequency spectrum.  The EMF produced from Extremely Low Frequencies is considered non-ionizing.  The transponder which modulates the signal onto the powerline typically generates about 0.3 milligauss or 0.03 microTesla of EMF.  Also, non-ionizing EMF strength decreases quickly as the distance from the source increases.  Therefore, the level that could be measured inside the home will be less than this and can be considered negligible at a one-foot distance.  For comparison, in 1992, the Swedish Confederation of Professional Employees established a standard which recommends limits on the EMF emission of computer monitors.  This standard required that they should produce no more than 2.0 milligauss at a distance of 30 cm (about 12 inches) from the front surface of the monitor and 50 cm (about 20 inches) from the sides and back of the monitor.  Included is a chart of EMF readings from common appliances at a distance of one foot.  Also, the transponder is typically on four times per day, and for less than eight seconds per transmission.  As a result, the AMI system transmission schedule results in less than 32 seconds of total transmission time, per day.

 

 

Other articles that may provide useful information are:

More information:

  • This article provides a good description of the different types of AMI communication technologies that exist and their history.  It also describes the difference between an AMI system and an AMR system. The systems which require a vehicle to drive-by and “pick up the signal” would be described as an AMR system. FreeState’s new system would be described as a PLC AMI Network (scroll about halfway down the page).  http://www.elp.com/articles/powergrid_international/print/volume-14/issue-8/features/ami-communications-technology.html
  • This article provides additional information about the different types of EMFs.  This article does include a chart discussing EMF levels near power transmission lines, with a voltage of 115 kilovolts and above.  Please know that the lines that FreeState owns and operates near your home are not considered transmission lines because they utilize a much lower voltage. The transformer that feeds your home is energized at a primary voltage that is typical for this region, 7.2 kilovolts. https://www.niehs.nih.gov/health/topics/agents/emf/index.cfm
  • This is an article available from the American Cancer Society regarding “Smart Meters”.  This article seems to focus on radiofrequency (RF) waves.  Again, please keep in mind that FreeState’s system is not RF based. https://www.cancer.org/cancer/cancer-causes/radiation-exposure/smart-meters.html