Ethernet over Power (480V)

motion guru · Dec 17, 2020

Is anyone aware of an Ethernet over Power solution for 480V circuits? We have found units that can do 120V and 240V, but would like to find a unit that can do 480V so that we can connect to devices that are on a crane busway without having to go wireless or add an Ethernet cable to a festoon.

trochoidalpath · Dec 18, 2020

There's a bunch of stuff to communicate over high voltage power circuits (10-400 kV) so the technology does exist. I never worked with it directly but I remember it being not very fast and I am not sure it would be even remotely cost-effective. I have never seen an industrial environment where they didn't just run STP or fiber alongside the power path.

Milland · Dec 18, 2020

Dumb question - small 480-240 transformer? It's not like you need a lot of capacity...

Ziggy2 · Dec 18, 2020

Most power transformers act as chokes at the frequencies/speeds needed for Ethernet communications.

Milland · Dec 18, 2020

Ziggy2 said:
Most power transformers act as chokes at the frequencies/speeds needed for Ethernet communications.

Thanks for that.

Figured it was a dumb Q, just didn't know why... :confused:

EmanuelGoldstein · Dec 18, 2020

Milland said:
Dumb question - small 480-240 transformer? It's not like you need a lot of capacity...

I believe he's talking about the ethernet on the power lines like they did through house wiring a while back. It never worked very well ... I reluctantly did a wireless network in a pretty big shop, was surprised how well that turned out. Bought a hotsy-totsy antenna for the access point and never had any troubles with fubar transmissions or dropped bits or anything. Had to use d-link wireless bridges for a few controls that had ethernet i/o built in, was surprised how well that worked, too.

The alternative was running fiber, which would have been a bit of a pain but all the stuff is available and not that expensive. Not sure how big motion's shop is but even cat 6 is not that great over long distances. I'd be skeptical of the eth-over-powerlines systems if the distance were very long and/or the lines ran parallel in any conduit ...

drcoelho · Dec 18, 2020

You'll want to look for products used by the public utilities. Utilities use coupling capacitors to link radio transmitters to power lines, these products can be placed on one, two or three conductors depending on the product. Not at all clear that the utilities are using ethernet protocols, more likely industry specialized protocols.

That being said, I think you are going down the wrong path. I would recommend you set up a simple in building wifi network, very easy and inexpensive and much more reliable solution.

motion guru · Dec 18, 2020

Not for our shop, rather for customer projects.

We are presently doing this over two phases of 230VAC 3-phase and it works well. Many of our customers forbid a wireless connection and finding a 480VAC solution would solve a number of problems with several applications we are working on.

drcoelho · Dec 18, 2020

Funny thing is, ethernet over power lines is probably LESS secure than WiFi as it is pretty easy to pickup E&M signals off the wires and I suspect that the ethernet is not encrypted.

You might checkout the various vendors in the HD-PLC Alliance, they are all doing Broadband over Power Lines: Members - HD-PLC Alliance which is the technology that will do what you need.

Mark Rand · Dec 18, 2020

I've done an hour or so looking for specific products over the last day. There are plenty of links to the ICs which do the logic (FSK etc), some links to development boards for same, many links which go back to power line communication enabled electrical metering or invertors, but I haven't yet found any specific links to an off the shelf 480V power line communication/module/modem/ethernet product.

There must be something out there, but it's going to be a small market.

The only major difference between a 110V/240V/480V module is going to be the matching transformer and possibly, the line driver circuit.

All of our manned cranes at work from 30T to 120T were converted to dedicated radio control with the riggers doing the job that the drivers used to do.

DDoug · Dec 18, 2020

Leads to credibility to Glen Campbell...."...I hear you singing in the wires...."..

motion guru · Dec 18, 2020

drcoelho said:
Funny thing is, ethernet over power lines is probably LESS secure than WiFi as it is pretty easy to pickup E&M signals off the wires and I suspect that the ethernet is not encrypted.

You might checkout the various vendors in the HD-PLC Alliance, they are all doing Broadband over Power Lines: Members - HD-PLC Alliance which is the technology that will do what you need.

Has nothing to do with security. These applications are in mixed business / industrial network areas all pumping data around in vast quantities. The customers simply don’t want us adding to the crowded WiFi traffic. The crane apps are auto positioning with targets transmitted to the cranes over Ethernet/IP . . . they additionally have a standard wireless pendant, but it is rarely used.

The riggers in this case cant be trusted to not damage the expensive payloads so cranes are guided by laser trackers, with target updates coming in to control sway, compensate for payload sag, etc.

Mark, I have found similar results as you. Looks like a product opportunity.

gustafson · Dec 18, 2020

Kinda surprised there aren't euro 400v units. Not 480 but at least you could contact the manufacturer and see if it would work at 480

pb1 · Dec 18, 2020

Assuming it is a 3phase 480v system check out what this company did: https://www.egauge.net/docs/277v-hpt-manual.pdf

The important part is the lower half of page 5. It looks like you can use a *small* stepdown transformer (small so that it doesn't act as a filter) on both ends to plug in a 120v powerline ethernet adapter on both ends. The transformer they list in their kit (TR50VA008) seems readily available. It will only use one phase and neutral (277vac) and step it down to 120vac that can be used with a 120v outlet.

motion guru · Dec 18, 2020

pb1 said:
Assuming it is a 3phase 480v system check out what this company did: https://www.egauge.net/docs/277v-hpt-manual.pdf

The important part is the lower half of page 5. It looks like you can use a *small* stepdown transformer (small so that it doesn't act as a filter) on both ends to plug in a 120v powerline ethernet adapter on both ends. The transformer they list in their kit (TR50VA008) seems readily available. It will only use one phase and neutral (277vac) and step it down to 120vac that can be used with a 120v outlet.

I noted that same article . . . which I think proves the point that there is very little on the web about doing this. We have a couple of 120-240 VAC units that we will try this with. That specific transformer can be connected to 480V phase to phase and output 120V which would work fine with the EOP units we are using now.

drcoelho · Dec 18, 2020

I would think you could use an autotransformer that keeps the signals intact, might at least be worth an experiment.

pb1 · Dec 18, 2020

motion guru said:
I noted that same article . . . which I think proves the point that there is very little on the web about doing this. We have a couple of 120-240 VAC units that we will try this with. That specific transformer can be connected to 480V phase to phase and output 120V which would work fine with the EOP units we are using now.

I think that most any machine you run 480V to you can just run an ethernet cable to or fiber to, so no one really does it. I can get behind not wanting to pull another cable in an already installed machine though. Ethernet Over Powerline is usually there for people who don't want to open up their walls (i.e. renters). It looks like the latest version seems to be "HomePlug AV2" with support for gigabit speeds. I'd love to know how well it works, although I seriously doubt I'll ever have a need for it.

motion guru · Dec 18, 2020

We started down this path when we embedded 3 motion control enabled servo drives inside a 15 foot long 16 inch diameter spinning tube that was fed via a slip ring. The drives were mounted to a carriage that travels inside the tube from one end to the other. Having communications go through a single flex rated power cable inside the tube and a slip ring to go from stationary tethered point outside the tube dramatically saved cost and complexity. This worked well @ 230VAC using a pair of consumer grade units from NetGear.

Now we are looking to solve this problem with auto positioning cranes where adding flex rated Ethernet over 175 feet of bridge travel is more complex and more expensive than if we can get this system to work @ 480V.

drcoelho · Dec 18, 2020

My suggestion stands, try using 480V to/from 230V autotransformers, these transformers have common connections to the primary circuit and thus theoretically can transmit the communcations signals. These can be very small transformers since you are moving almost no current.

DDoug · Dec 18, 2020

175' might not be festooning, rather it might be bus bars.

Can you run an IR link ? Put stationary unit at one end of rail, shooting along the rail.
pickup on bridge.

Do you need to just get to bridge, or all the way to the trolley ?

Might be a simple mirror on the bridge to turn the IR 90 degrees.

Ethernet over Power (480V)

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