Power Over Ethernet Interference - Page 1
Forum section: electronics / projects

author: PixieDust
author_rank: Frequent Contributor
timestamp: February 08, 2018, 08:19:23 am
content: Hi,I'm trying to figure out whether Power Over Ethernet is going to suit my needs.The most extreme scenario that I can think of with POE would be sending a large file via ethernet i.e. you've got a long data stream over 2 pairs and then I'm randomly switching the full 25.5W load on and off over the other 2 pair while the file is being sent.Question is, am I going to get data corruption from emi?

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 08, 2018, 08:32:42 am
content: 1) Why would you be randomly switching a 25.5W load on and off? That isn't typical POE use.2) TCP/IP has many layers of data checking, error detection, and error recovery. Unless you are doing something really goofy, it seems rather unlikely.

author: dmills
author_rank: Super Contributor
timestamp: February 08, 2018, 09:22:06 am
content: Yup if you follow the specs correctly it will work just fine (even over a 1Gb/s link using all 4 pairs for both data and power).Regards, Dan.

author: woody
author_rank: Frequent Contributor
timestamp: February 08, 2018, 10:55:12 am
content: Well, when you switch the load off the datastream is going nowhere, is it? So emi seems the least of your worries.

author: PixieDust
author_rank: Frequent Contributor
timestamp: February 08, 2018, 11:23:09 am
content: I'm just providing a worse case scenario, there's going to be a minimal load to power the device, but there's going to additional power required at random points in time.Quote from: Richard Crowley on February 08, 2018, 08:32:42 amInteresting point.Quote from: dmills on February 08, 2018, 09:22:06 amWhere can I get the specs for it? I'm only finding random power points and other info about it, nothing official.

author: xani
author_rank: Frequent Contributor
timestamp: February 08, 2018, 11:59:12 am
content: Quote from: Richard Crowley on February 08, 2018, 08:32:42 amMaybe he wants to power house lights with poe. Think about it, IoT lighting perfect use for PoE, no pesky WiFi to get hacked and 25W is plenty for LED lights

author: woody
author_rank: Frequent Contributor
timestamp: February 08, 2018, 12:46:49 pm
content: Quote from: xaniThat has been done:https://www.networkworld.com/article/3034861/cisco-subnet/cisco-announces-new-digital-ceiling-iot-solution.html

author: Monkeh
author_rank: Super Contributor
timestamp: February 08, 2018, 12:56:49 pm
content: Quote from: PixieDust on February 08, 2018, 11:23:09 amhttps://standards.ieee.org/findstds/standard/802.3af-2003.htmlhttps://standards.ieee.org/findstds/standard/802.3at-2009.htmlYou may want to consider the superseding standards - namely 802.3-2015, I believe.

author: djococaud
author_rank: Regular Contributor
timestamp: February 08, 2018, 01:14:40 pm
content: Switching a big load after receiving large file, is it for Li-Fi ?I think it would work, but I would still add a beefy cap on the receiver in order to reduce EMI on the Ethernet cable...(and lower the stress on the power supply)

author: PixieDust
author_rank: Frequent Contributor
timestamp: February 09, 2018, 02:23:25 am
content: No Li-Fi, just need to vary the power consumption of the device.Thanks for the links.