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Need help with GFI tripping problem

Discussion in 'Power Supplies' started by Greg.Ca, Oct 19, 2013.

  1. Greg.Ca

    Greg.Ca Apprentice Elf

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    I built a power supply box with 6 Meanwell 5-350's for powering my 36 5VDC WS2811-WS2812B strips. Each strip is actually a 'half strip' being 2.5 meters long and only 75 pixels.

    Everything is actually working fine however lately I have been having a problem powering up the power supply box without tripping out the GFI circuit breaker. Power from this is from my garage and all outdoor outlets in America by code have to have one of these GFI outlets to safeguard against electrical current going to ground. We have had this safety standard in America for as far as I can remember. Decades.

    These six meanwell power supplies each have their individual 'hot' shutoffs as well as a master shutoff for removing the 'hot' for ALL power going to these six meanwells. I have tried individually to isolate as to which meanwell might be tripping the GFI. But it appears to be random and 'additive'. No individual power supply seems to be the culprit. I usually can get 5 of them power up but when I energize the 6th one it blows the GFI circuit every time. I need reliability.

    These power supplies are wired up very simple. A hot(switchable and fuseable), a commen neutral to ALL of them, and the green ground is wired to the steel frame of my enclosure.

    This problem is a MAJOR show stopper. If power drops out from this outlet. I lose ALL of my RGB project as well as anything else plugged into that outlet. I also have my D/A converter, my transmitter and several LOR controllers plugged into that outlet. Right now ONLY my RGB power box is plugged into that outlet and it is tripping the GFI fairly consistently. Seems to happen more in the morning. All of my 36 light strips are in the garage in a dry environment for testing and for deployment for Halloween. We live in as very dry climate so moisture is not the problem. I'm at my wits end trying to figure out why this design is tripping the GFI. BIG NUISIANCE!!

    Also, each power supply has a fine tune adjustment for voltage output. I believe that the voltage out is set fairly exact at 5.00 however I want to turn it up 100mv to 5.1 so the strips get at least 5.0 when energized. Thoughts??

    Any ideas what to do?? --Greg in Denver Colorado
     
  2. David_AVD

    David_AVD Bite my shiny metal ass!

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    I think Andrew Frazer posted about a similar situation some time ago. Maybe search through his posts or PM him to see what the solution was.
     
  3. penguineer

    penguineer Full Time Elf

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    You're not drawing too much current(amps) on one power circuit are you?

    What else is on the same circuit as the power outlet you are using?

    How long of a delay are you leaving between starting up each of the individual power supplies?

    As each unit starts up it may have what they call "inrush current" which will be pretty near max draw for that unit - have you tried starting each PSU at at tme and letting it settle for about a minute(to drop to normal draw) before turning on the next PSU?

    This sounds very similar to various power issues I've had to deal with/avoid with computer systems over the years......

    If you're having this issue with load before blinky-flashy starts you may have to move some of the PSUs to a different circuit.......

    Cheers!
     
  4. Adam007

    Adam007 Adam007

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    This is what immediately came to my mind. I don't know about in the US, but here in Australia each circut is only good for 10 amps.
     
  5. OP
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    Greg.Ca

    Greg.Ca Apprentice Elf

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    To give further information, No, it's not an excessive current problem. When this GFI tripping is happening, there are NO pixels illuminated at this point. There are also no other AC loads on this circuit. In America because our voltage is only 110-1120VAC at each outlet, our usual maximum current is 15 amps. Sometimes 20 amps. In this case, it is 15 amps but when the GFI trips, the AC current is LESS than 1 amp as there is very little load on the AC supply. Remember, no pixels are illuminated yet at this point.

    The GFI is not tripping because of over current. The GFI is tripping because of microamps or milliamps of 'leakage' current to ground FROM the hot is being detected by the GFI circuit. There is a difference or 'imbalance' of current flowing on the hot as there is on the neutral. Normally for every electron that flows on the hot, there should also be an EXACT amount of current flowing 'returning' on the neutral. This 'imbalance' of current between the hot and the neutral is what trips any GFI circuit.

    I have tried to 'start' up each power supply one at a time and it does no good. By the time I get to the last power supply, the GFI trips. HELP!!!
     
  6. David_AVD

    David_AVD Bite my shiny metal ass!

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    I assume your "GFI breakers" have separate indicator tabs that show whether the trip was due to current or imbalance?

    The issue is likely to be the leakage current caused but the EMI filter components in the power supplies.
     
  7. AAH

    AAH I love blinky lights :) Community Project Designer

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    I recall that Meanwell supplies have the V- connected to earth as a safety feature. I am also reasonably certain most other brands are the same. I can't recall if they are directly connected to earth or just via a low ohm resistor. What might be occurring is the inrush current as the 5 supplies all power up at the same time causing a momentary blip with the GFI. It is entirely possibly that you have no fault at all but it is just an interaction between the supplies and the GFI. Your only option may be to stagger start them. 1s between startups is probably all that you need as the inrush is typically over within a few cycles of the 50Hz or 60Hz mains.
     
  8. David_AVD

    David_AVD Bite my shiny metal ass!

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    I took it to mean that when he powers them up in sequence (one at a time, but leaving the previous ones on) the breaker trips as the 6th one is switched on.

    If so, it's likely to be that the accumulative leakage is just over the GFI threshold with all 6 powered up. The simple solution is to split the load over two power circuits with their own GFI.

    At home and work, I have separate RCD/MCB on every power circuit. This minimises accumulative leakage issues and limits power outages to just the affected circuit. Also makes fining finding the offending item a lot easier.
     
  9. David_AVD

    David_AVD Bite my shiny metal ass!

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    I've not seen a switchmode supply that connects DC- to frame/ground myself. Here's a block diagram of the SP-350 that shows the EMI capacitor going to ground as well as one from DC- to ground.
     
  10. AAH

    AAH I love blinky lights :) Community Project Designer

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    lol at the typo David. After finding them the offender gets fined :)

     
  11. OP
    OP
    Greg.Ca

    Greg.Ca Apprentice Elf

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    What is RCD/MCB ? --Greg--
     
  12. ԆцряєсϮ

    ԆцряєсϮ Senior Elf

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    RCD. - residual current device
    MCB. - Miniature circuit breaker

    AFAIK. :)
     
  13. Charl Marais

    Charl Marais For my twins was the excuse I started with.

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  14. OP
    OP
    Greg.Ca

    Greg.Ca Apprentice Elf

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    And why would you be rolling on the floor laughing?
     
  15. Charl Marais

    Charl Marais For my twins was the excuse I started with.

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    It took me like 1/2 a afternoon to look up all the acronyms myself and as soon as I log onto the forum again they are all explained. If I had stayed on a bit longer I would have saved myself a lot of sifting through similar looking/sounding acronyms trying to puzzle out if they are the correct ones :)
     

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