Connect with us

Grounding a power supply

Discussion in 'Power Electronics' started by norranesnah, Jul 4, 2013.

  1. norranesnah

    norranesnah

    3
    0
    Jul 4, 2013
    I have a power supply for a pool cleaning robot that had a faulty timer. It is a really simple power supply that uses 120v A.C. input and uses a transformer to step it down to 30v A.C. Anyway, I needed to bypass the timer to get it working, however, I am not yet sure it is safe to use. Originally there were three wires that went from the timer circuit to the female plug that the robot plugs into: black, white and green; presumably hot, neutral and ground. The green is spliced with the white wire at the plug, but is currently not connected at the other end now that the timer is gone. I am worried about electrocution, especially since the power supply is to be used next to a pool. Where should I connect this ground wire?

    Hopefully I explained it clearly. I will take a picture of the wiring tomorrow when my camera battery has finished charging. Another thing that confused me was that the output plug has a ground terminal that is unused, and the case itself is already grounded to the main ground wire at the input.
     
  2. davenn

    davenn Moderator

    13,246
    1,745
    Sep 5, 2009
    hi there
    apologies for the late welcome

    please show us some sharp and well lit pics of the existing system
    if there's a PCB involved show both sides :)

    Dave
     
  3. norranesnah

    norranesnah

    3
    0
    Jul 4, 2013
    Thanks Dave. I got around to taking pictures later than I expected, but here it is. I also made a schematic since it might not be very easy to see what is going on with the wiring.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Jul 5, 2013
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    The most likely answer is "to the metal case".

    Be sure to use an earthed outlet.
     
  5. norranesnah

    norranesnah

    3
    0
    Jul 4, 2013
    Oh okay. That's what I thought at first. I have been trying to understand grounding better, and I just didn't want to do anything without understanding exactly why. I was under the impression that ground and neutral were supposed to be kept separate for safety reasons, so why are they spliced together? Another thing I don't understand is why there is three prong plug at the output where the ground pin isn't being used. If anyone could shed some light on these things for me I would really appreciate it.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    30VAC is relatively low voltage. One side of it is earthed so that it can't float up to a higher voltage, especially if a fault develops in the transformer or any attached equipment.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-