Remote energy metering/PLC 10

[Skogsgurra]

This is not about Programmable Logic Controllers - but Power Line Communication. The PLC acronym is used for both so there may be some confusion. But, as said, this is Power Line Communication.

The questions I want some views on are:

A How often are electric power meters read in your area? Other meters (gas, water, heating, cooling etc)?

B What technology is mainly used?

C Are several different technologies used to achieve 100 percent coverage? If so, do you use GSM, internet, fiber, copper, radio link, meter man, other for the "difficult" meters?

D In what stage is your organization? Fully implemented PLC? Partly implemented (how many percent?? Planning stage? Not considering PLC/remote metering at all?

E How well does your implementation work? If there are any problems, please indicate what technology causes the problems and if you think that the situation will improve or if that technology seems to be a blind alley?

F How do you handle the VFDs? What filters have proven effective?

G Any other thoughts?

I am asking this because I have been involved in countless discussions on this subject lately. The reason is that I work with EMI from VFDs and other power electronic devices and that they seem to be a problem for the PLC. (Yes, there are filters, I know. But they seem to short out the PLC carrier as well as the EMI from the VFDs).

There seems to be as many opinions regarding the future of PLC as there are individuals. Please help deblurr the picture by answering this mini-enquête. The more answers we get, the clearer the picture will be.



Gunnar Englund

http://www.gke.org

 

[dpc]

skogsgurra,

In the US, meters are typically read once a month. For residential, most are still read "manually" the old-fashioned way. Automated Meter Reading (AMR) is a hot topic in the US. Most of the systems around here use a small radio transmitter in the meter or meter base. The meter is then "read" by wireless link to a computer or hand-held device in the meter reader's truck - they just drive a route, collecting meter data as they go. This data can then be downloaded to the billing system.

Power line systems are available in the US, but not much used, at least that I am aware of. The "drive-by" radio systems seem to be much more common. I have one at my house, actually - a Turtle -

http://www.hunttechnologies.com/

For larger industrial/commercial metering installations, some local utilities actually use cell phones in the meter and dial in to read the meter.

There is a misguided effort toward "Broadband Over Power Lines" (BPL) in the US that might have similar interactions problems with VFDs, but it has a lot of its own EMC/RFI problems.

You could also check out Itron - they seem to be the major AMR player in the US.

Sorry I can't answer more of your questions.

Dave

 

[itsmoked]

skogsgurra,

I can't answer many questions on this either.

Once a month almost without exception.

Usually walk by.

Eight days ago the city (water) people came by and changed our water meter out for a radio one. (Something to do with our 14 foot high, eight foot wide, hedge that surrounds our house and the attack chickens) I interrogated the ring-leader. He said the meter could now be read by a handheld wand from several feet away or by a more powerful transmitter/receiver from farther away. He indicated the arterial a block away. He said there were two down sides. One the batteries in the water meter would only last 11 years. Eleven years for a receiver is pretty amazing to me!! I have yet to see a transistor radio work for eleven years on a battery. Or one year for that matter!

The other problem he stated was that with no one reading the meter monthly the meters(which include the emergency shut off) get lost. He stated an example where two weeks earlier it was found that six meters had been paved over by a road crew two years earlier and not detected until an emergency arose.

As for VFDs causing a problem how would they affect a large residential area? Carrier current generally has so many little problems with it that I can't imagine it being successful in a broad city application.

I worked on a carrier current data acquisition system for refrigerated containers to allow monitoring of refrigerated containers while en-stacked on ships at sea. This was a specific definable power network. We still had a ton of problems with things blocking and shunting and degrading the signals. It was very difficult! We even blew a 2,500A 480V 3ph breaker feeding 400 refrigerators with one of our interface units.. It was a very difficult project fraught with demons.

I wouldn't go that route I'd go with radio if I was trying to go no-additional-wires in a facility.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Skogsgurra]

Thanks. Very interesting answers. Exactly what I need to know. But two opinions isn't enough. Must be a lot more people with experience/knowledge out there. The more the merrier... Post on!

Gunnar Englund

http://www.gke.org

 

[itsmoked]

It is Sunday you know!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Skogsgurra]

Yes smoked!

But I guess lots of people will find this so interesting that they forget about BBQ, fishing rods, baseball and what have you. Just to write down interesting facts about PLC.



Gunnar Englund

http://www.gke.org

 

[jghrist]

The luncheon speaker at the Georgia Tech Relay Conference Thursday was with the United Power Line Council

http://www.uplc.org/

that promotes BPL. There are a large number of pilot BPL programs in the USA, but not many in full operation.

Not much was said about AMR, but it was mentioned that BPL may interfere with some AMR systems. Something to look into.

 

[tinfoil]

In Canada, it is common for power utilities to read industrial/commercial meters once a month, and to read residental meters every 60 days. Some utilities bill all monthly, and some bill residential only 6 times per year.

We have had several AMR sales guys retreat from their sales pitches once they realize that their business cases don't work if 90% of the meters are only being read 6 times per year.

In addition, that once-a-year inspection that utilities may still insist upon reduce the avoided trips from 11/year to only 5 per year!

 

[Skogsgurra]

That is a new point of view. We still have utilities that read once a year. Not much need for anything but a human being there.

Legislation is going to once a month, so something has to be changed, though.

Do you have a feeling that the existing AMR installations using BPL are reliable and succesful? Or are they plagued by EMI from drives and other interference?

Gunnar Englund

http://www.gke.org

 

[stevenal]

We are presently using the Turtle system in a primarily residential area. The only problems I'm aware of are in the optical interface that reads disk revolutions. We've had better luck with fully electronic meters. The low frequency signal is unlikely to be affected by VFDs. Customers as well as utilities are required to meet IEEE 519 requirements, so most new VFDs should be well filtered. The three players I know of in AMR that use PLC are Turtle (Hunt), TWACS (DCSI) and Centron. The signals they use are proprietary and have little relation to the BPL internet signals that are being hotly debated.
Manual reads and Turtle reads are monthly. Most utilities with the higher speed PLC based AMRs read more frequently so that any problems can be detected before month's end.

 

[stevenal]

Sorry. Centron is a meter. The last PLC based AMR player I meant to include above is Cannon.

 

[nayden]

skogsgurra,

In Bulgaria the energy meters are read every month. The whole procedure tooks about 3 days mostly, however, instead of every efford, the data is biased by subjective errors.
The reliability of wireless measuring solutions is not proven yet because of the higher price. Implementation of new digital meters with common data transfer protocol is now available.

 

[ScottyUK]

itsmoked,

Is it possible your water meter is a turbine meter which uses the turbine as both the flow transducer and as a source of electrical energy?


----------------------------------

I don't suffer from insanity. I enjoy it...

 

[itsmoked]

Hi Scotty.
I would use that technique like mad if I designed it. I failed to ask and would imagine no stated battery life if they did. (SuperCaps)

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Skogsgurra]

Good idea for those who wants to get the last penny out of everything: Let the tap water run a little hydroelectric generator and utilise the otherwise lost pressure difference between system and kitchen sink.

Waddayathink? Much better than that exercise cycle idea that has been floating around for some time? ;-)

Sorry - didn't mean to steer this highly serious (yes, I mean it) thread off topic.

What about BPL, PLC and other ways of meter reading? Come on.

Gunnar Englund

http://www.gke.org

 

[dpc]

There is a lot of (negative) information on BPL at

http://www.arrl.org/tis/info/HTML/plc/.

They have done some testing around the few systems that are actually installed in the US. And there is this link to an overview of PLC/BPL:

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

My understanding is that BPL has been banned in Japan due to RFI problems/concerns.

None of this directly answers your questions, but might be of interest as background info.

 

[tommom]

Consider contacting the American Public Works Association. I just went to a presentation they gave on this very topic.

 

[waross]

Hello everyone.
This question has generated a lot of interesting and new information for a lot of us. I think skogsgurra deserves a star for an excellent question.
Respectfully

 

[RalphChristie]

Gunnar:

A. In South Africa, most places I am aware of, read it once a month. In the mine where I am working we use it mainly for electricity, fuel (diesel and petrol) and water.

B. Still a lot of old disc type meters, but electronic meters are winning field.

C. Meterman, Fibers and Radio-link. Internet access in the pipeline.

D. Electricity
66kV from utility: 100%
66kV internally: 80%
11kV internally: 70%
400V internally: 40%
Fuel
100%
Water
10%

E. I would say good. In places like with the fuel system it is excellent, due to the fact that fuel is much more expensive than water or electricity, almost forcing them to monitor it very closely. For the electricity there are a lot of things in place, but it is very poorly utilized, meterman is still used with everything in place. (also on the electronic meters) Maybe not seeing it as that important due to the fact that electricity is fairly cheap or maybe people still used to the old practices?
Can't say we experience really problems with any method, small problems encountered sometimes on all of them, but not something to complain about.

F. -

G. -

Regard

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[wfowfo]

We have two AMR systems, the Hunt Technologies T1 system and the CTI (Cannon Technologies) system. Hunt also makes a newer version (the T2) but I'm not that familiar with it.

The Hunt T1 system is an ultra-low frequency (5 to 9 hz) PLC that can take anywhere from 12 to 27 hours to transmit a reading (depending on how much info you are trying to get). Very dependable, very little signal attenuation, extremely cheap and easy to install. The meter device pulses a capacitor that puts a signal on the sine wave that a CT picks up in the Substation. One way communication. You must take certain precautions if you tend to switch loads back and forth between substations.

Our Cannon Sytem uses a 12.5 Khz signal that is injected via a coupling capacitor at the substation. Information is real time . Communications work both directions so it can be used for readings, disconnects, controls, etc. Requires blocking devices on capacitor banks to prevent bleeding the signal to ground. Has excellent support. Initial installation is much more expensive than Hunt T1, but has much greater versatility.

TWACs is similar to Cannon, but uses a special transformer to inject the signal. Don't know a whole lot about it, but Pedernales Electric Coop in Johnson city, Texas uses them extensively and can probably give you some good info.