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Eath leagage trips

Discussion in 'Power Supplies' started by keithsw1111, Dec 4, 2015.

  1. keithsw1111

    keithsw1111 Full Time Elf

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    I have been struggling the last couple of days with irregular earth leakage trips which shut down my show (and th bosses TV).


    I have been desperately trying to isolate the problem and while I have some theories nothing is crystalising as a single it must be that cause.


    I have periods when my show runs for an hour or more without problems looping through my entire schedule several times then shuts down pretty much randomly and typically does so again several times as I attempt to reset the earth leakage breaker. It then will run for another 30 mins or more no problems.


    I am suspecting it is one or maybe several of my power supplies over heating (it does seem to get worse towards the end of the night). To address this i have applied some dimming factors to some display elements to try to lower the draw and slow down the over heating. When I touch the power supplies there are a couple that are warm but none are really hot.


    Would really appreciate some troubleshooting suggestions.


    Some details ... the supplies are the typical ray-wu ones in a mix of 5, 12 and 24V. Each have a large clear exhaust port over the fan and are all located well out of the weather. There are varying numbers of lights attached to each.


    I was using some of the 24V to switch high current relays. I figured this might be a problem as I did not put a resistor in series with the coil to limit the current but removing these from the show does not seem to have stopped the problem.


    Apart from the power supplies I have disconnected all my 240V elements so there is not likely a fault in any of them causing the problem.
     
  2. David_AVD

    David_AVD Bite my shiny metal ass!

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    Each power supply may be leaking just a little current. It sound like your house has a single RCD and this means that the total leakage for all circuits may be bordering on the 30mA limit.

    Ideally you should run your show from a separate circuit with its own RCD. At my house, every circuit has it's own RCD/MCB combo.
     
  3. lithgowlights

    lithgowlights Senior Elf

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    Like David, my house has individual RCD's on each circuit and I am yet to have one trip. I think David might be on to something with the cumulative leakage as I know one box here wont work on my 10mA plug in ELCB setup used in some hospitals (Don't ask - it was thrown out when we did an upgrade so I grabbed it for testing). That box has 4 PSU's and trips the 10mA in just a few minutes, but that and about 10 other PSU's all run ok on a single 30mA 20A circuit...
     
  4. Greg.Ca

    Greg.Ca Apprentice Elf

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    In America we have what is known as GFI or GFCI circuits which by electrical building code is required in all rooms of the house that have water. (kitchens and bathrooms and ALL outdoor circuits). These GFI breakers monitor leakage from hot to ground.

    If some circuit return flows from hot to ground instead of hot to neutral, then in milliseconds the hot is 'opened' thus potentially preventing an electrocution. In theory, this seems great but in reality if using multiple power supplies on the same circuit this 'leakage current' adds up and seems to trip the GFI breaker thus causing your display to go dead. It's a real nuisance.

    I use separate data and power boxes for my pixels and my power boxes seemed to trip my GFI circuits after 5 Meanwell SE-350-5's were put on the same 120VAC circuit. My solution was two fold.

    I use two separate 'legs' of 120VAC power to supply my power supply boxes. Not just two different feeds. Two different 'legs'. This has an additional benefit of balancing current consumption as electrical current is split between the two 'legs'.

    All my Meanwell SE350-5's power supplies run from 120VAC. However I put half of them on one 'leg' and the other half of them on the other 'leg'. The voltage BETWEEN the 'legs' is 240VAC but none of the power supplies are run from 240VAC. This reduces the power supplies/circuit and cuts my leakage current in half. See the attached photo.
    In the photo you can see the two separate electrical feeds on the left and right sides of the photo.

    The other solution was to run the Meanwells on NON GFI circuits. Not recommended. This is ok if using indoors. GFI circuits are not used in indoor residential or commercial non 'water area' rooms.

    Meanwell makes low leakage medical grade power supplies that spec leakage current in the micro amp range. Not milliamp range. In my opinion this is the way to go and the safest. All my commercial and outdoor residential designs use this power supply.

    These medical grade power supplies cost double what regular Meanwells cost and these cost double of what cheap Chinese knock-offs cost but they TOTALLY resolve my issues and allow me to use GFI circuits thus keeping me in compliance with mandatory electrical safety requirements. We certainly don't want to electrocute anybody.

    Remember what my kids father always says: "Long after you pay for quality, you forget the price."

    https://www.trcelectronics.com/ecomm/pdf/msp450.pdf

    Buying cheap Chinese counterfeit power supplies saves you no money in the long run and actually cost you plenty.
     

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  5. logandc99

    logandc99 Dedicated Elf

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    I recently had a problem with the RCD (same as a GFCI) tripping randomly. Sometimes I could get all power point on and the show would run ok, sometimes couldn't run it on at all. And it wasn't just one powerpoint, it was quite random.
    So I contacted the electrician and suggested we had a faulty RCD. He came out, checked everything and came to the conclusion that it must be the RCD and so he replaced it. Since then, all is working fine ( I also asked him to put the outdoor power points on their own RCD so the rest of the house wouldn't go dark every time the outdoor tripped the RCD).
    So, maybe worth making sure your GCFI isn't faulty before tearing your hair out trying to figure out which of your power supplies is misbehaving. Just something to consider.
     
  6. Beacy

    Beacy It's so much better on the dark side

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    I had huge grief with this last year and had 2 new outlets put in this year for lights and it's own RCD and no problem this year apparently new requirements is max of 3 outlets per RCD
     
  7. multicast

    multicast Senior Elf Generous Elf

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    Just for clarity, the terms RCD and GFCI are the same thing, just our US friends had to call it the something different.


    (1) Your RCD may or may not be faulty.. Its well worth testing them, to see. A low cost RCD checking device is avaialble at Jaycar.. It works by deliberately putting a load between Phase and Ground at varying currents. If the RCD pops you know you it works.. Better testing is avaiable on many PAT ( portable Appliance Testing ) devices, which will also meaure the time it takes to trip the RCD. That is important. You dont' want it taking seconds to trip. ( that can happen )..

    (2) Switch Mode Power supplies inherranty are electrically noisy things, and one of the things they do to stop "noise" getting back onto the AC power supply is put Filtering caps between Phase and Earth, and Neutral and Earth. ( Its sometimes called a Y filter ). Its an effective way of stopping the buzz. However, that buzz is real energy ( all be it not a lot ), and it is being dropped into the Earth. The RCD works by detecting an imbalance between the currents flowing in the Phase and the Neutral. If some of the energy that came in on the Phase, leaves via the Earth, by implication the current in the Phase and Neutral will not be the same. And bang, off goes the RCD. The amount of energy lost in the filter will be mostly proportional to the load on the PSU.. It sometimes is also noisy on turn on.

    (3) Fixes for this;

    - Use low leakage PSU's. expensive and only really avaialble in low power ratings.
    - Reduce the number of SMPS's on a single RCD circuit untill its under the threshold.
    - Ideally, run multiple RCD's on multiple circuits.
     
  8. David_AVD

    David_AVD Bite my shiny metal ass!

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    The 8 Mean Well power supplies that I use for my display are all on one circuit with it's own RCD. They are a mix of SP-320 and SP-240 models.

    Upgrading to an RCD/MCB combo per circuit is not all that expensive. I think I paid about $30 each for the "single pole size" units and maybe $200 for the electrician to do the work.

    I think it was well worth the money, even from the non-Christmas point of view. If something trips an RCD, the search for the offending device is narrowed down straight away. It also means that critical circuits (fridge / freezer) won't lose power due to a fault on another circuit.
     
  9. scamper

    scamper Senior Elf

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    There is one other possibility that no one has brought up yet, and I am only theorising, not knowing how your house is wired.
    New circuit breakers now days are also rcd's (eliminates another switch in your box)
    If this is what is tripping, then it could also be that you are drawing too much current through the one breaker and not be an earth leakage at all.
    You say it is random and the wife's TV stops also, but what else is she running inside?

    If this is the case, I suggest moving some of your load to a different circuit to alleviate the problem, which is the same solution as everyone else before me came up with anyway. :)
     
  10. multicast

    multicast Senior Elf Generous Elf

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    The new RCBO's are really handy when you go to install them, someone thought about how they were going to be installed pretty well!


    https://www.clipsal.com/Trade/Products/Switchboards-Circuit-Protection/Residential/Combination-MCB-RCD#.VmIiquOGRBc
     
  11. Greg.Ca

    Greg.Ca Apprentice Elf

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    To my Australian friends, In America we have GFI's..... "Ground Fault Interrupters". What does RCD stand for ??Residential circuit ???? Not a clue. --Greg--
     
  12. AAH

    AAH I love blinky lights :) Community Project Designer

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    Google knows all. It's "Residual current device" and it's the same thing as GFCI.
    https://en.wikipedia.org/wiki/Residual-current_device
     
  13. David_AVD

    David_AVD Bite my shiny metal ass!

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    This is the type I was talking about. Sometimes called RCD/MCB or RCBO (I think). They are a combined device.

    They have a little window with a flag that displays a different colour on over-current or leakage trips. Really handy for seeing what type of event it was.
     
  14. Ɠαяєтн

    Ɠαяєтн Mae gen i C.L.A.P ei heintus iawn

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    It sounds like you may have a couple of different scenarios going on here. Not knowing how your switchboard is configured, but usually in Australia they have an RCD (Safety Switch) feeding perhaps 2 or 3 MCB (Circuit Breakers), typically lighting and power (sockets). The purpose of the circuit breaker is to protect the cable, lighting is 10A and sockets 16A, as per AS/ANZ 3000:2007. So this means that if your load (power supplies and tv + other) goes over the 16A MCB it will turn of the power to this circuit protecting the cables from overheating.


    However what sounds like is happening is your RCD is tripping. This device has 2 components, 1 is the load current rating typically these are 40A in domestic switchboards in Australia and 2. the safety components , this is a sensing coil and trips if there is an imbalance in Live Neutral of more than 30mA typically (tripping current) e.g. an earth fault. This would be shown on the front of your RCD by the words "40A 30mA".


    The load current rating of an RCD works the same as a circuit breaker so effectively it is like an RCBO like David described. This load current breaking has 2 characteristics as shown in the attached drawing. 1 is thermal which operates over minutes and the second is fault which operates in seconds. What sounds like is happening is that the total current for all of your MCB circuits that are being feed from the RCD are overloading the load current rating and tripping it thermally, this would explain why with the TV on and anything else, e.g. kettle during the Ad breaks what is tripping the RCD.


    As others have stated the second option is that the tripping current on all circuits is greater than the 30mA, but I would suspect that this would happen more consistently and you would now the device e.g. water down the back of the kettle plug was causing the problem.


    To fix the problem is the same as others have suggested, replace your RCD and MCB with RCBO or combo units. It would also suggest that when employing a licenced electrician do do this you add a couple of adding circuits for the Christmas Lights.


    Don't forget to ask for the safety certificate when the job is completed this way you'll know the job is done correctly and have the test data.


    To simply check an RCD or RCBO for the tripping current, press the test switch on the front of them. Manufacturers recommend that this is done on a monthly basis and perhaps good to remember at the beginning of the show period.
     

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  15. multicast

    multicast Senior Elf Generous Elf

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    In our workshop, RCD checks are done weekly. Its only our lives at stake. Given that we often have live exposed work on our bench.
     

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