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Electric Company Using Power Lines for Data
Snags writes: "The local electric company PPL Utilities is testing a system to send electricity usage readings back to the company over its own power lines. According to a local newspaper article, they are using the TWACS system made by DSCI. I'm just hoping this doesn't interfere with other ideas for sending data over power lines."
I seem to remember that power companies were doing this way back in 1998... Am I wrong? or do I just need to put down the pipe?
A proposal to use power lines in the UK for data transmission was dropped because of a number of difficulties, most notably the fact that HF radio (about 2MHz to 30MHz) would have been rendered unusable in urban areas. Street lamps made great quarter-wave antennas.
Many power companies have fiber up on the high voltage towers - which generally terminate in metro areas and rural areas at power stations - they use it now mostly for substation monitoring and internal networking. However, given the bandwidth potential of this fiber - they've got the ultimate backbone available. They just need to get that last mile figured out - no easy task!
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HydroQuebec, in the provinde of Quebec (duh!) tried this a few years ago (circa '97).
At the time, there were a number of obstacles that made this technology unworkable. If I remember correctly it had something to do with electromagnetic field sensitivity. The earth's EM and solar flares made the whole system too error prone, at the time.
This brings up another memory. A company, 10 years ago, had a cheap office wiring system that used the ground outlet as a network transport. With their adapter, any machine plugged (quite literally) was on the same network.
What made that idea (and company, I think) fold was the lack of security. Anyone could connect to your house's power outlet and get connected. Furthermore, there were no filtering devices that served as "firewall" between your house and the external power grid.
TWACS currently reads at 300bps. There's technology out there that will up that, but it isn't going to get anywhere near what's needed for a decent Internet connection anytime soon.
My husband has been working with DCSI for about 2 years on the system in NE WI and there have been a few issues with interference, but not with homes and shit. The pulses aren't strong enough to interfere with normal shit, though there was one incident of a substation - which sends time synch pulses out to individual meters - setting off the railroad crossing alarms every 15 minutes.
It's a better solution than using RF to transmit the readings back to the sub - most of those are using 900MHz to transmi and you can imagine what kind of problems THAT causes.
I don't have a solution, but I certainly admire the problem.
Our competitor got their hands slapped pretty bad by the public utility commission for that one and had to eat the entire investment. There was just no justification for such fancy toys to handle such a low-tech task.
sPh
IIRC from my tour of a substation years ago, electricity suppliers use power line carriers (PLC) to communicate between substations to relay switching information. If you happend to be driving by a substation, look for these large cylinders called wave or line traps, that are used to "capture" the RF signals...Cool stuff especially since they are operating on something like a 500kV line. Probably a much simpler modulation scheme though.
"Karma can only be portioned out by the cosmos." -Homer Simpson
We canned the idea for Internet, but this application sounds ideal; low bandwidth, low contention (presumably), and if it goes wrong, you can always send the legacy meter readers around in a van... Or you could upgrade all your kit, I wonder which one they'll opt for...
UNIX? They're not even circumcised! Savages!
There's very little in common. TWACS works by doing phase-shift modulation on the 60Hz carrier; this is a wonderfully robust method when implemented correctly, but at best you get a bandwidth of a few tens of bits per second. This is great for reading power meters (where a few bits per hour is plenty of bandwidth) but it has nothing to do with high-speed internet connections.
I was outside the house the other day and noticed that my electric coop had installed a new meter. Upon closer inspection I noticed a little red light on the meter. Curiousity was peaked so I called up a friend of my that works for the coop and he went into a long explaination about these new meters they are rolling out. He called them Turtle meters and a quick net search turned up http://www.turtletech.com/Products-Sales/standardt urtle.htm
To quote their website
It monitors kilowatt-hours and records peak and minimum demand. The data is time-stamped and is continuously transmitted across the utility's own power lines. As long as the meter has power, the Turtle transmitter can provide a count of short outages (blinks) and establish whether the transmitter is in power fail.
The Standard Turtle transmitter can be programmed to return one of eight different data transmission options. The time needed to transmit a complete packet varies from 13.9 to 27.2 hours depending on the amount of data being transmitted.
Which falls in line with my friend telling me that it can take a day to get a reading because they are using a super low frequency. So yeah, they can remotely read meters. But they have definite problems with lightning. My friend spends a lot of his time in the summer replacing the Turtle units in the meters because they fry very easily he says. But they are cheap enough that it is still cheaper than sending a meter reader to all the houses.
Hunt says they've been doing this since 1995, so its not new, but few people have seen it because it has taken a while to get them out.
I think my local power company (FPL) is using a two way version of this for their ON CALL system. This lets them brown out selected appliances in your house (such as your water heater or Air Conditioner) for brief periods during high power demand. You tell them which appliances you will let them control and they install a special box between them and the power line. They only brown 'em out for brief periods (I forget what the max power cycling periods are). For this you get a lower rate on your power bill. Makes sense for some people.
I live in Reykjavík Iceland, and the power company here has already implemented internet over powerlines, although only a few people are using it now it seems to work just fine.
I guess we can use this technology because the entire population is about 280.000 people (and about 260.000 of them use the internet) check out Fjöltengi even though most of you wont understand a word of that page, you can check out the pic of a chick using the magical-gadget on the main page.
Hitler's in the fridge.
Shutting down services on your panel selectivly MY ASS.
Its not that bad, really - Xcel Energy in Minnesota has a summertime power saver option which is basically a box that attaches to your central AC compressor power tap and control line. It listens for a "shut off" signal from the power company and cuts the control line which actually switches the compressor.
The advantage is they promise a minimum amount of downtime (like 15-20 minutes per) and only during peak energy hours (8-5 or something). I've been home when they've done this and unless its the hottest day of the year (high humidity, lots of sun) you don't even notice -- the blower on your AC keeps running inside air past the condensor coil, so it feels "on" even though its not. I've heard some people say that notice a slight uptick in internal temperature, but I haven't.
The major bonus is a 15% discount on ALL electrical power for the summer months. That's like getting free AC as infrequently as I use it, or an excuse to run it twice as often for the same money.
It'd suck to have your dryer or something else shut down at random, but AC during the day is not a big deal, trust me.