Broad band over powerline

[wfowfo]

The Texas Public Utility Commision has recently approved a Smart Metering initiative that least two companies are trying to accommodate via BPL.
My knowledge of the technology is limited, but I understand it involves a significant number of coupling capacitors to get the high frequency signal across inductive devices like transformers.
If this is correct, has anyone seen any safety issues doing this (i.e., coupling primary to secondary voltage)?
If my grasp of the technology is in error, feel free to enlighten me.

 

[Skogsgurra]

Hello,

I have done quite a lot of testing and faultfinding on AMR (Automatic Meter Reading) equipment using PLC (Power Line Communication). The frequency range used is between 9 and 150 kHz - most signals are in the 50 - 90 kH range. The systems that I have seen do not transmit across transformers. Instead, there are data collectors taking data from each meter and transmitting data to concentrators that usually (always) are situated where the transformer is. Data are then transmitted from the concentrator via phone/ADSL, fibre or radio to the central computer at the utility.

I would also be concerned about safety there. Especially considering what lightning does to capacitors.

The Turtle system (very narrow-band, I think something like .5 mHz at frequencies between 90 and 110 Hz), is able to transmit across transformers. But Turtle is very low frequency and does not rely on capacitors for transmission - only for modulation. And that is always done on the low voltage side.

Turtle is considered very reliable, but I have had cases where old frequency inverters have washed out the signals. I have recommended that those old inverters be replaced by new ones. Modern inverters do not (to my knowledge) disturb Turtle.

What systems are they contemplating?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[wfowfo]

They are talking full blown internet. The metering part is to encompass 15 minute interval data and real time pricing.

 

[Skogsgurra]

But not internet on MV lines?

Do they, really?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[dpc]

Unfortunately, it is over the MV lines:

http://glasnost.itcarlow.ie/~net4/kirwans/bband.html

I'm hoping it dies a quick painless death....

 

[Skogsgurra]

There is not much said about MV communication there, only that future systems will use inductive coupling to MV. MV is mentioned in one picture - but it doesn't seem very convincing.

Tone signalling over 220 - 400 kV lines has been in use for ages. But that is not BPL.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jghrist]

This was a hot topic in the municipal market a couple years ago, but I haven't heard much lately. Try

http://www.bpltoday.com/iqpc.html

for more information. Ham radio operators tend to object because the MV lines become very large antennas and the frequencies are in the unlicensed spectrum.

 

[06Hardrocker]

Not too long back the Cooperative Research Network (CRN) released a report on BPL technology. They tested two different companies products. Personally I believe the results were lackluster.

NRECA members already have access to this report (CRN project 04-13 "Broadband over Power Lines"). I do not know the cost of this report for everyone else, but you maybe able to fins something on their site:

http://www.crn.cooperative.com

Cheers, Kit

 

[06Hardrocker]

I am sorry. That post should read "NRECA members MAY already have access" as not all NRECA members are part of CRN.

I apologize for the typo.