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Old 26th Nov 2021, 1:54 am   #21
joebog1
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I can see by Sychrodynes post we should have stuck with DC. Its great for long distance attenuators.
So even two phase was one phase further than DC, or even single phase AC. Tesla at least built Niagra and proved the system would work. I dont suppose he could just rip down to local electrical suppliers and buy up a large slab of grain oriented generator laminations.
As I read in the books about Tesla, the "laminations" were iron wire dipped in shellac for insulation. I guess a commutator wasnt exactly easy to obtain either, or even the machining required to make one. REMEMBER noboday had ever built one to this point in time, so where was the model to copy?

Westinghouse didnt treat Tesla very well as I read, nor Bell for that matter. Its very interesting that Bell invented the telephone just when Tesla worked for him. Or Westinghouse that just happened to invent the Westinghouse brake while Tesla worked there. What about the steam turbine? etc etc.
Teslas papers ? all taken by the American government as I remember reading.

Its easy to write somebody off, but I stick with my origional statement. Or I will even go further, probably the most influential inventor of modern times.

Just my take, and I do defend Tesla, his work influenced me to try and be an engineer in the first place, all taught me by my father who attended his lectures in Austria sometime in the 20,s.

With respect

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Old 26th Nov 2021, 9:00 am   #22
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

This video explains what it is 600Hz down Ethernet style cables?
https://www.youtube.com/watch?v=wlNkiQj2YQ8

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Old 26th Nov 2021, 9:22 am   #23
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I've looked at some of the marketing material and it looks like it's just switching power down a twisted-pair wire at about 700Hz, and adding some data to each "packet" of power. I haven't yet seen whether the power is DC or high-frequency AC or something more complex. As far as I can see, a "packet" is just a short period when the power is switched on. Presumably the data element allows for some negotiation of voltage/current/power between transmitter and receiver. The receiver's job is to smooth out the received power and convert it to whatever voltage and current the eventual recipient of the electricity needs.

The data transmission element also seems to allow for some error checking - if the data doesn't get through correctly, the power gets switched off.

It strikes me that, as far as the wiring is concerned, interference need not be a problem if it's twisted-pair, or if there are no high frequencies and fast edges involved. Conceptually it seems similar to the earth-free wiring systems employed in some marine applications: the power is isolated from ground, so it's safe to touch one wire, and there's earth fault monitoring so that if either leg of the wiring accidentally gets grounded, the power is shut down. In this way no single fault can lead to a dangerous situation. Ideal for hazardous situations or shonky wiring. The latter is what digital electricity seems to be promoting - no need to comply with those pesky expensive mains wiring standards any more. There are situations where that really makes sense, like powering of remote equipment where only light-gauge, single-insulated cables are available or affordable, and the cost of the additional equipment is justifiable.

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Old 26th Nov 2021, 9:27 am   #24
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I can see the cheapness in not having dedicated mains supplies, as it says it can take solar, battery a.c. Then to me it is like a slow switched power supply, everything goes to a DC level and is chopped to a lower voltage to make it safe say 50 Volts and distributed to max 24 circuits per server each with monitoring built in. That way they can use normal safe low voltage circuits to pass the supply to the receiver which I would assume reforms it to what is required either a.c. or leaves it as DC but at what ever voltage is required. It says that each server can provide 3kWatts, so I can see in a building potentially several 3kW 600Hz transmitters having long antennas made up of potentially unshielded cable which could mean several hundred meters or wire. OK it is low frequency but lots of potential for unwanted harmonics taking out the VLF spectrum so hope decent filtering is used.

Also I would wonder about efficiency low volts more amps per circuit more resistive loss?

Adrian

Many points picked up by Chris there, my slow typing again.
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Old 26th Nov 2021, 3:32 pm   #25
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

Looks to me like an updated/better Power Over Ethernet, makes sense in the long run as most devices we use now are low power needing DC. I remember some years ago having a conversation with a very experienced consultant electrical engineer who designed large scale power systems. He siad if we were to start again we should use high voltage DC not the AC of Westinghouse/Tesla as we can now control it much more easily.
So maybe this is the future of power. Nothing works until it has negotiated a safe connection, just think of all the fun troubleshooting that! Probably won't be widespread within the life time of the members of this forum though.
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Old 26th Nov 2021, 3:36 pm   #26
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

Quote:
Originally Posted by chriswood1900 View Post
Looks to me like an updated/better Power Over Ethernet, makes sense in the long run as most devices we use now are low power needing DC. I remember some years ago having a conversation with a very experienced consultant electrical engineer who designed large scale power systems. He siad if we were to start again we should use high voltage DC not the AC of Westinghouse/Tesla as we can now control it much more easily.
So maybe this is the future of power. Nothing works until it has negotiated a safe connection, just think of all the fun troubleshooting that! Probably won't be widespread within the life time of the members of this forum though.


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Old 26th Nov 2021, 5:02 pm   #27
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I still can't work out what it does...
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Old 26th Nov 2021, 5:54 pm   #28
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

As far as I can make out there's a 1.5mS cycle - voltage is applied to the line for 1.1mS, the line is released for 0.4mS during which the line is tested for fault conditions and some fairly limited control data is passed.

Because of the 'self test' shut down on fault condition it avoids the 100VA limit on Class 2 cicuits (as per POE) because NEC accepts this as a 'limited power source' circuit. Class 2 installation saves a lot of money, not only because of the reduced physical requirements as compared to Class 1, but also because it doesn't require the services of a qualified electrician. (Not to be confused with IEC Class I and Class II...)

https://www.electronicsweekly.com/ne...ables-2021-10/
Quote:
VoltServer told Electronics Weekly:

Digital Electricity has 336Vdc peak to peak, which is actually ±165V. The max current per pair out of the transmitter is 3A.
We can achieve up to 2.4kW and up to 2km. 2.4kW is limited to about 500ft [~150m] with one of our receiver models, and at 2km [6,500ft], we can achieve 400W with a different receiver model.
We use multi-conductor pair cable. Although some vendors call it ‘Digital Electricity cable’ it is simply copper [see Belden link below].

Safety is enhanced with digital over-sight, according to Vicor, which is supplying dc-dc converters for some of the receivers: “VoltServer takes electricity and breaks it into small energy packets,” said Vicor. “Each energy packet is analysed using a digital signal processing engine to determine that power is being safely distributed, and if a fault is detected the next energy packet is not sent. Each packet contains only a very small amount of energy, so individually they are not harmful to people, animals, systems, or buildings.”
https://www.belden.com/products/cabl...erOfResults=25

https://www.vicorpower.com/resource-...rver#solutions

Cheers
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Old 26th Nov 2021, 6:09 pm   #29
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I might be wrong, but I think some previous comments show you misunderstood.

The words "transmitter" and "reciever" do not mean radio, this is cable driving.
So it is just beefed up Power over Ethernet.

The problem they are trying to solve is that they want to take the already highish PoE voltages beyond what allows it to be safe, while having the system classified as a safe low voltage system thus dodging onerous wiring regulations.

So my understanding of their idea is they send the power in short high voltage bursts (hopefully well balanced) and in the gaps they use some clever patented technique to decide it they are killing anyone. If the answer is "no" then another power burst occurs, etc.

Now I am not sure that would be legal in the UK ??
To my mind this comes close to the idea that we can wire mains with tacky cables because we have an RCD that (if working) will stop us dying too badly.

So who wants to stick their fingers up its sockets to see if the clever system actually works??
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Old 26th Nov 2021, 6:49 pm   #30
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

It's no good, I can't see what this thing is meant to do or its purpose. Maybe I'm thick or cynical or just plain stubborn-of-mind, but *** is digital electricity?
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Old 26th Nov 2021, 7:03 pm   #31
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

From what I can work out, it's a pulsed system in which pulses can contain a 'preamble' of digital data that tells a device connected to the system "this pulse of power is for you". So you can send power to specified devices.

It also has the benefit that being essentially a mix of SELV and addressability, the voltages are such that the cabling/installation can be done by unskilled staff rather than qualified electricians.

Ideal for things like LED lighting, or the sort of 'check-in kiosks' you find in hotels, the "your train has been delayed by 35 minutes" annunciator panels in train/bus-stations etc.

Now, if someone can only develop Power-over-Fibre......
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Old 26th Nov 2021, 7:28 pm   #32
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

You're not alone, Andrew, it's still causing me brain fade.

Safety sells, to be sure, but over-complication breeds problems that (i could argue) didn't need solving in the first place. Another issue: when it goes wrong no-one but the originator and his elves are going to be able to fix it...and how does the consumer truly know whether it has been fixed?
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Old 26th Nov 2021, 8:37 pm   #33
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

A lot of good info here-some I can even [sort of] grasp. I've never understood much about 2 Phase Synchrodyne and I suspect the Horizon Documentary was probably wrong about that but they were concentrating on sources of inspiration as much as anything else! There's been quite a few hints over recent years [on here and elsewhere] re new industrial techniques using DC voltage "chopped" in some way. Does it apply to off shore Wind Farms and power cables across the channel. Wasn't there supposed to be one carrying Geo-thermal electricity from Iceland.

Of course all this has the benefit of a much later technology than was available at the turn of the century. Edison's plan to have a DC generating stations, every four blocks or so in New York, sounds like a nightmare on every level, coal powered, cables as thick as your arm etc

What caught my eye at first with this Internet Power proposal was the reference to "packets". I recall these [using information] were quite an interest within the Amateur Radio computer community at one time. Perhaps this proposed power distribution system has similarities as information [now more expensive than oil in some estimations] is at the basis of both systems? The power transmission seems to boil down as "more for less" by achieving regulatory compliance a different way.

I hope that's in no way comparable to tweaking diesel engines to meet the grade though.

Dave W

I'm intrigued that your father actually saw Tesla giving a lecture Joe [post 21]. Did your dad ever write anything about that experience or describe what he was like?

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Old 26th Nov 2021, 8:57 pm   #34
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

Dave, Dad never really talked too much about that time. He did explain who Tesla was, and what he had invented. Dad passed over 30 years ago, and my memories of a kid have faded too.
I do remember him having a good laugh at the DC followers though.


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Old 27th Nov 2021, 1:47 am   #35
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I have seen one or two lithium battery chargers that send power to the battery for a short time and then stop and measure the terminal voltage.
It stops charging when the off charge voltage test reveals the maximum full charge value for the specified battery has been reached.
I found this out when building my own charger with discrete LEDs in place of a single dual LED.
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Old 27th Nov 2021, 10:10 am   #36
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I think the point of the "packets" is just a way to achieve the safety aspect. Since it is putting out significant power then I am guessing that the receiver end sends digital data back after every power period to say exactly what power it received, so the transmitter end can check if that is right. If not it will shut down. If it didn’t check then a fault could set fire to something.

The shortness of the power bursts is also to limit the damage to anyone touching the wires. If it can precisely tell that all the power it transmits was definitely received OK then it isn't going anywhere else - so must be safe.

So a very complicated way to achieve safety for an otherwise dangerous system.

Slightly off topic: if this kind of system was used for the third rail supply for trains then we would not need those hideously ugly overhead lines.
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Old 27th Nov 2021, 12:16 pm   #37
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

Next thing you know, your electricity is encrypted by either a commercial or political entity or by some random ransomware... I'm not sure we need this.
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Old 27th Nov 2021, 12:39 pm   #38
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

That grow light system may well be monitored from the sending end with the figures from the data sheets supplied by the LED manufacturer loaded into the sender.
Like with the lithium battery in post#35 the controller can check the spec of the load as often as it is programmed to do.
I would be more interested if it could work with a complex load such as a washing machine where it would be monitoring all the loads it sees during a wash cycle.
It would then have a link with the programmer at the load end to get the info about the expected load.
If a component drifted out of spec the controller would see something other than the load as per the spec sheet. The unit should report the component that should have been properly connected at the time and shut down. The only advantage I see is that you can order a spare part before you visit the load item to fix the fault.
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Old 27th Nov 2021, 8:56 pm   #39
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

More interesting views! How does that avoidance of an overhead gantry work GMB [post 348].
I'm looking at using the self contained new battery or hydrogen units that have now been developed. Is that a "Third option". Running trams [without an expensive overhead wire or tunnel space] would mean that extending the route from Bury [along the ELR could become viable]. I'm only interested in the connection with power distribution folks not an OT railway discussion.

Thanks for the response Joe, post 34*. Your Dad sounds very interesting!

Dave W
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Old 1st Dec 2021, 8:09 pm   #40
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Default Re: Just when you thought Networking-over-Mains was bad for RFI

I think these are the relevant patents:

https://patents.justia.com/patent/20160134331

and this set from the company mentioned...

https://patents.justia.com/assignee/voltserver-inc

The idea seems to be just to interrupt the supply in a pattern and measure behaviour of the channels(s) when you do so.
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