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Trouble finding 120V DC - 10A breaker.. alternatives..

Discussion in 'General Electronics Discussion' started by alesserfate, May 14, 2017.

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  1. alesserfate

    alesserfate

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    Dec 5, 2014
    Hello All..

    I currently have a 80DC 10A carling / bluesea breaker that I use to engage / protect / disengage the PV side of my solar array.

    I am looking to add 3 more panels so my PV DC voltage would rise to at least 112.5V DC (each module is 22.5V and with my controller they run in series). Therefore I need to find an ~120V DC, 10A breaker that I can use in a similar configuration. Open to other solutions as well but keep in mind: 1. Wiring in parallel is NOT an option in my application; 2. I want to avoid using a switch and a fuse.

    This is my current form factor and the less modification required, the better. Although I'm more than willing to buy a different PVC box for it and modify it to fit as needed.

    Thanks in advance.

    [​IMG]
     
  2. Bluejets

    Bluejets

    3,684
    758
    Oct 5, 2014
    Moeller Schneider make a range of circuit breakers to suit solar installs.
    Most we have anything to do with are higher voltage and 6Ka rated but that would make no difference to your application.
    Most authorities require use of double pole breakers for the incoming dc off the panel.
     
    alesserfate likes this.
  3. alesserfate

    alesserfate

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    3
    Dec 5, 2014
    Thanks for your input. Pardon my inexperience, what's the reason they want double pole breakers for PV DC isolation ? Would you recommend it in a small application such as mine ? I have 500W Solar and an MPPT controller.
     
  4. Bluejets

    Bluejets

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    Oct 5, 2014
    Safety.
     
  5. alesserfate

    alesserfate

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    Dec 5, 2014
    Still looking for a breaker if anyone knows, didn't find anything suitable for 120VDC, 10-15A on the Schneider site.
     
  6. Tha fios agaibh

    Tha fios agaibh

    2,078
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    Aug 11, 2014
    It doesn't need to be rated exactly120vdc.
    There's nothing wrong with going to a higher voltage rating such as 250vdc or even 600vdc. The current is the important thing.

    Selecting the correct current rating is not as simple as just limiting it to the pv arrays maximum rating.
    I recommend you take a close look at the Cec and the Nec to make this code compliant and safe. Specifically art 690.

    Normally the fuse or circuit breaker protection is located after the inverter not before it.
    I realize it's only 500w, but it's still enough to be dangerous so following electrical codes is wise.
    For instance do you have a safety disconnect that's clearly labeled and readily accessible if someone unfamiliar needs to shut it off?
     
  7. Bluejets

    Bluejets

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    Oct 5, 2014
    Both are used, input and output DC and AC.
    DC isolators adjacent to the panels are also a requirement in many instances, depending on your location.
     
  8. alesserfate

    alesserfate

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    3
    Dec 5, 2014
    Thanks guys. I agree with the current rating - that's what's important as that's the throughput that the system can handle and needs to be protected with.

    To make it completely clear, this is how this solar system is currently set up and is in a boat, and is how the instruction manual and code requires it to be set up in its current application.

    [67.5V Solar array in series] -> [circuit breaker (the one you see highlighted red in the picture)] -> [MPPT charge controller capable of outputting up to 40A 12VDC to battery bank] -> [40a circuit breaker (seen in the picture on the left)] -> [400Ah battery bank] -> [200A breaker] -> [2000W Inverter] -> [AC Main]

    So to answer your question, yes I do have disconnects to disconnect the system entirely, and they are the two toggle breakers you see in the original picture I posted. As far as the labels.. I'm getting there! :)

    The manual didn't call for double pole breakers on the PV to MPPT controller link, but only on the positive). However there is a double pole 30A breaker on the AC main after the inverter.

    I will keep looking to find a 120VDC+ breaker thats in the 10-15A range as thats what the manual calls for, there are lots of VAC rated breakers in that range but not VDC. Thanks again for your input.
     
  9. Tha fios agaibh

    Tha fios agaibh

    2,078
    687
    Aug 11, 2014
    Personally I'd prefer to use a fuse.
    I don't know if they have 10-15 adjustable, but here's a 10a DC breaker.
     

    Attached Files:

  10. alesserfate

    alesserfate

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    Dec 5, 2014
    Thanks for finding that! I couldn't find it, it actually resembles my form factor which is good. By 10-15A I meant that the manual calls for a breaker in that range of amperage, doesn't have to be adjustable. I appreciate it.
     
  11. Tha fios agaibh

    Tha fios agaibh

    2,078
    687
    Aug 11, 2014
    I realize your codes are different, but make note of the fact that pv arrays can output more than their ratings so fusing and wiring are required to be sized 125% of array.
    That is, if this was under Cec or Nec code.
     
    Last edited: May 19, 2017
  12. alesserfate

    alesserfate

    29
    3
    Dec 5, 2014
    Thank you I am aware, the manual calls for a slightly larger safety factor to be used for that exact reason. The only thing I would do better than this specific breaker is to find an 'outdoor panel' rated one where all the components are tin plated and has a ring terminal post rather than a 'wire insert port', since the marine environment, even inside the vessel tends to destroy everything that's not stainless or tin plated very quickly and with a ring terminal post I can use a tin plated lug end and heatshrink any exposed copper away from the moisture. I am already using CSA TEW 105C tin-plated copper 'boat cable' rated but still extra protection is always good since when you cut the ends the copper gets exposed at the cross section.
     
  13. Tha fios agaibh

    Tha fios agaibh

    2,078
    687
    Aug 11, 2014
    You could mount it to a piece of din rail inside a weather proof box with cordgrip fittings (strain relief) enclosing each conductor.

    Look up Nema enclosure ratings.
     
    alesserfate likes this.
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