-48Vdc power adapter

Discussion in 'General Electronics Chat' started by zainisma, Oct 23, 2013.

  1. zainisma

    Thread Starter New Member

    Oct 23, 2013
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    0
    Good day all,

    I am new here and would love to get some feedback regarding a small project that I am involved in. I would like to find out if I can get an off the shelf product/solution towards transmitting a -48Vdc down a 100meter/~330ft AWG10 or AWG22 wire cable. This line would be used to power a Wi-Fi AP mounted on a communication tower.

    Currently, (the predecessor to this project I am working on), uses a +48Vdc supplied using a PoE (Power over Etherrnet) down a 100meter cable. The decision to consider using a -48Vdc was based on some benefits identified by the project manager.

    So, any help would be appreciated.

    Thank you in advance
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    There are TONS of -48VDC power supplies.. Its the most common voltage used in the telecommunications industry.
    I'd be VERY surprised if there wasn't -48V or +24V already available at the base of the tower.

    Who owns the tower? (have you discussed your intentions/needs with them)
    Is there a hut/small building at the bottom of the tower?
    What power source do you have available there?
     
  3. zainisma

    Thread Starter New Member

    Oct 23, 2013
    3
    0
    Thank you mcgyvr for your feedback. I really appreciate it.

    Although I must first apologize for not clearly stating my problem in my initial post. Unfortunately, the location for this project's proof of concept (PoC) does not have a communications tower or a base station. Therefore, there are no available -48Vdc power source to tap from. The only power source that is available would be a 240Vac wall outlet (a shelter), which is in the middle of a piece of land meant for agricultural use.

    So, I have been trying to source through alibaba.com, element14, mouser.com, etc for an AC/DC power adapter (I am thinking along the lines of a regular power brick adapter), that would take a 240Vac (50Hz) and convert it to a -48Vdc output. But so far my search has not been very successful, which I feel is odd since you mention that -48Vdc is the most common voltage used in the telecommunications industry.

    Again, I would really appreciate any information/suggestions/recommendation that anyone in this forum would like to share.

    Thanks again.
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    They are typically referred to as "rectifiers"..

    Eltek/Eaton/GE are a few of the major suppliers...

    But any 48VDC output supply where the either the + lead is tied to chassis ground or both leads floating can be used.. Just don't get one where the - output lead is tied to chassis ground. Mouser had 500+ 48VDC output supplies..
     
  5. zainisma

    Thread Starter New Member

    Oct 23, 2013
    3
    0
    Thanks again for the feedback mcgyvr. So, you're saying that I do not have to look for a power brick AC-DC adapter/converter that pushes out a -48Vdc; and I can purchase any off the shelf 48Vdc out AC-DC adapter. Right?

    I just have to make sure that the Voutput does not have its negative pole connected to its own chassis (the power adapter chassis) or earth. Right?

    So with this 48Vdc (across its '+' pole and '-' pole), I just need to connect the '+' pole/lead to the ground of my Wi-Fi AP chassis/PCB-ground-plane (PCB), and the '-' pole/lead to the power line (a PCB trace). By doing that, I should get -48Vdc as my input into the Wi-Fi circuit board. Is this correct, or am I waaaaay off?

    Many thanks.
     
    Last edited: Oct 25, 2013
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