Can data be reliable transfer over high power DC line ? - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: May 14, 2018, 08:05:52 am
content: Hi folksI have a questionI have a DC power line 160V nominal (200V peak) and power goes to ones of kW drawn by multiple SMPS so it will be noisy environmentCan I transfer data/control signals over this line reliably or will I have to use separate cable for data ?Transfer range should be about 50 meters

author: rs20
author_rank: Super Contributor
timestamp: May 14, 2018, 08:21:28 am
content: At least naively, you should be able to put an LC filter (or LCLCLC filter) on the supply cable at the SMPS end. If the maths works out right, the inductor(s) would keep the SMPS noise and signal carriers separate, so you could tap off your signalling before the inductor.Main killer for this idea would be that the capacitors and inductors might need to be huge, depending on the amplitude of the noise. You can always just drive a stronger signal too, of course.

author: David Hess
author_rank: Super Contributor
timestamp: May 14, 2018, 01:39:51 pm
content: It can be done even in a noisy environment. Modulate the data onto a carrier, inject it, and then demodulate it at the receiver.There are various power line communication ASICs made by ST, TI, Maxim, and others which could be used.

author: paulca
author_rank: Super Contributor
timestamp: May 14, 2018, 03:08:58 pm
content: Isn't this how 100V line speakers work at outdoor events?

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 14, 2018, 03:54:03 pm
content: Quote from: paulca on May 14, 2018, 03:08:58 pmNo. "Constant-voltage" speaker systems sent just raw AC audio signal at "high" voltage to minimize cable losses. And also to allow the designer to tap off however much power is allocated for each speaker. There are several popular voltages like 25V, 70V and 100V. The 70V variety is the most prevalent IME.Ref:https://en.wikipedia.org/wiki/Constant-voltage_speaker_system

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 15, 2018, 03:12:27 am
content: How much bandwidth? It's pretty easy to send HDTV over the mains nowadays. And it's surprisingly robust. DC should only make things easier.If there's also a ground in addition to "hot" and "neutral" (whatever the DC equivalents are), you can try putting the signal between ground and neutral, although then you'll need to use Y rated coupling capacitors when X rated would have been fine between hot and neutral.

author: ogden
author_rank: Super Contributor
timestamp: May 15, 2018, 05:59:53 am
content: Quote from: Miyuki on May 14, 2018, 08:05:52 amIndeed you can transfer data reliably. There are many Power Line Communication (PLC) chips/solutions around which are designed for application like yours - noisy power lines. Electricity meter reading PLC's have much harder work to do than your 50m of power line.Kind of basic/easy PLC modem that comes into mind isTDA5051a. Reference designas well.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 15, 2018, 07:17:31 am
content: Apart from the Homeplug AV (what I used in my example) that's commonly sold for LAN purposes, there's also Homeplug Green PHY intended for much lower bandwidth applications, although that doesn't seem to be very popular yet.

author: Miyuki
author_rank: Frequent Contributor
timestamp: May 18, 2018, 07:53:29 am
content: Some of these chips are nice, but price is terribleRF 433/868MHz transceiver cost fraction of their price

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2018, 08:43:48 am
content: Quote from: Miyuki on May 18, 2018, 07:53:29 amWell.. You can't have it allSub-GHz transceivers are many orders of magnitude more popular that powerline communication IC. As we all know, sales volume usually defines price.Chip itself is only half of your problem. Hi-power coupling LC network (at both ends of power line) can cost more than IC. So PLC communications shall be use only when there's no other options (to use RF).