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WET54G and Power over Ethernet

Discussion in 'Other Linksys Equipment' started by ncollingridge, Feb 21, 2005.

  1. ncollingridge

    ncollingridge Network Guru Member

    I must admit to being VERY confused by the situation wrt Linksys support for PoE. This is not helped by the fact that I can't find any specs for this feature anywhere.

    My situation is that I have three WET54Gs that I would like to supply by PoE. I have obtained some 802.3af PoE injectors which are totally standard - they inject 48v DC onto the appropriate pins. When I try and use the WET54Gs with these injectors, however, they seem to work fine APART from the fact that there is a hissing noise coming from the units which isn't there when using the 5v DC adapter supplied with the units.

    This sounds very much to me like the voltage regulators are being over-stressed by being fed a higher voltage than they are designed to cope with, but I have been assured by Linksys support (they didn't sound that confident about it though) that the WET54G is designed to work with standard 802.3af PoE injectors.

    If I could actually see some clear spec that says all is OK with this I might be happier, but as things stand I am not enthusiastic about installing these devices in case they just go pop in a very short time and I am called out to replace them at great inconvenience (they will be mounted in weathertight enclosures on three high chimneystacks).

    I would be grateful if someone could let me know what the exact situation is here. Seeing a release like the one above doesn't help that much, as Linksys here are clearly describing a version of PoE that doesn't conform to the 802.3af standard. It may be power supplied by the ethernet cable, but I think it is rather misleading to use the terminology Power over Ethernet, or PoE, when there is a standard for this which is at a different voltage than this Linksys kit.
     
  2. linksysonline

    linksysonline Network Guru Member

  3. ncollingridge

    ncollingridge Network Guru Member

    That's quite helpful, assuming that the WET54G is compatible with the WAPPOE (nothing I've seen makes this clear, or what PoE voltage the WET54G can accept). What it doesn't explain, though, is the hissing noise I get when I connect a similar PoE injector to the WET54G. Maybe that's the question I should be asking - is a loud hissing noise normal when the WET54G is being supplied at 48v via PoE?
     
  4. ecullen

    ecullen Network Guru Member

    I wish to use poe on the WET54G and would also like to know what voltage can safely be applied via the POE.

    Does anyone know the power consuption ? The PSU is rated at 2A so its something less than this. Anybody know ?

    Eric
     
  5. simax

    simax Network Guru Member

    I always thought that the injected voltage would be 12v DC.

    That's how I have it on other APs/bridges.

    Obviously, though, the higher the voltage is on the injection point the farther it gets (longer cable distances). As long as the receiving unit has voltage regulators...

    Most Linksys equipment is 12v DC, isn't it?
     
  6. RonWessels

    RonWessels Network Guru Member

    Check out this document to get a pretty good description of how Power over Ethernet works.
     

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