Power line communication PLC - power meter reading waveforms ?

[Externet]

Hi
How does the PLC data superimposed to the sinusoidal 60Hz waveform looks like on an oscilloscope ?
Are widely used common-mode choke filters also meant to block the data from entering sensitive equipment power supplies ?
Does the data passes trough the power meter or is it blocked from appearing inside a dwelling outlets ?
Is it a single-suscriber-at-a-time 'polling' the days power metering are read ?

Is there other data on the power lines not related to meter reading, monitoring power consumption/factor... like time of the day? Remember years ago marketed clocks that did set themselves after re-plugged in. Was/is the time read from the mains ?

Could a fire alarm in a dwelling be sent to the power company and then relayed to firefighters central office ? Or a critical/important traffic light failure transmit its distress signal and relayed to a corresponding repair entity ?
Is communication via power lines a monopoly of the owners of the transmission lines or is it open to public use ?

 

[ronsimpson]

It is hard to see small RF signals on 110/220V 60hz power line. The signal might be 1V or 1mV and on top of 110V it is hard to find. Also the RF is not synchronized with the 60hz so the scope will not lock on it.

I made a scope probe that isolates from the power line and hills the 50/60hz power. It is built to pass 100khz to 10mhz. Because only high frequencies pass to the scope it is possible to lock the scope to the RF.

Common mode chokes are made to block noise your equipment makes. It was not made to block data. The data is not common mode it is diff mode.

The data is not blocked by the power meter but is is blocked by the transformer on the power pole.

Power line talking for in home use probably transmits 100mW. I have seen 100 to 500 watt transmitted on long power lines. I think you can't afford a transmitter capable of transmitting to a fire station.

Yes it is close to a monopoly.

What other data: Years ago I lived 3 miles off a major power line. I was using my "power line scope probe" to trouble shoot X-10 communication i my house. I found many channels of data at 1 thought 10mhz. There were mostly concentrated at 1 through 5mhz. Using a RF filter I amplified each, one at at time. I call a friend that works for the power company. (engineer) and told him what I found. He said there is not RF on the power line. I told him what frequencies I found and then he said those should not make it though the transformer. Then he went back to there is no RF on the power line. I have him the ASCII data I found. It is mostly numbers. I think they are sending voltages for three phases and currents. There is some data that I can't understand but it is also mostly numbers. Then he told me they send and receive voltage/current/phase data from station to station. They can switch some stations by remote control. Then he added he thought the oil field was sending flow information on the power line but he had nothing to do with that and he really did not know who else was sending data but he could see some of it. Then he went back to "there is no RF or data on the power line".

 

[Externet]

Thanks a lot for sharing your knowledge.
About

...The data is not blocked by the power meter but is is blocked by the transformer on the power pole...

The data related to read the power meter is bidirectionally not blocked at the transformer, right ?

 

[ronsimpson]

I don,t know about where you are. My meters in Colorado use IR (infer red light) to talk to the meter man. He needs to stand in front of the meter with in 15 feet. The meter I have in Nebraska uses RF. The reader person drives down the street with a antenna out the window.

I don't know how to send RF down the power line through the transformer. And not enough power to make it to the power company.

 

[Externet]

Am at zip code 40322; very rural national forest. A clerk from the power company told me they do it remotely from the main office ¿? - The water meter reading yes, done by 1 guy driving by monthly.

 

[4pyros]

They use bypass caps on the transformers to get the signal around them.
You can look at some of the X10 stuff for an idea.

 

[KeepItSimpleStupid]

Smart meters are probably ZigBee based. There is some wireless data on the meter like MAC type addresses. What I've been told is that somewhere they may use a cellular modem to relay the two-way data.

The water meter, I believe, has to be read by passing nearby. It is battery powered.

The Gas meter uses the ZigBee network and now so does the peak shedding systems. Turn off AC unit.