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Schneider breakers curve type

Discussion in 'Technical Discussion' started by Pascal, Jul 23, 2021.

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  1. Pascal

    Pascal Senior Member

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    I may need to replace one of the chiller breakers on the Lazzara. One of them occasionally trips but resets right away. I wonder if the breaker is not getting weak.

    it’s a Schneider multi9 C60SP D63A which I suspect has been replaced at some point. The other chiller breaker which appears original is a Merlin Gerin multi9 C60N 63A type D

    I wonder what is the difference, if any, between C60SP and C60N. I ve been searching thru Schneider data sheets and can’t find the answer

    my second question is about the curve type. Both are type D which is for motors. Problem is that I can’t find one. Wards Electrics has type C in their catalog but not type D. Grainger has the type C available but type D is back ordered till end of august. Now, since the compressor start up gradually with frequency drives, would that not allow the use of type C breaker?

    Any electrical engineer familiar with these type of breakers? Any source besides Wards or Grainger?

    They re not cheap../ $166 at grainger.
  2. rtrafford

    rtrafford Senior Member

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    You want to go with the SP. Supplementary Protector, designed to provide additional circuitry protection for sensitive electronic systems, like chillers.
  3. rtrafford

    rtrafford Senior Member

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  4. mapism

    mapism Senior Member

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    I can't help you with US sources or anything else US-specific, but you are not comparing the same codes there.

    As a premise, bear in mind that Merlin Gerin was taken over by Schneider years ago, and while they kept the Multi9 name and the C60 designation for one of their product lines, they are now using a different coding for the other letters.
    The "N" in your old C60N M-G component referred to the kAIC (kA Interrupting Capacity).
    M-G used C60A for the 4.5 kAIC breakers, C60N for 6 kAIC, and C60H for 10 kAIC.
    Not that my memory stretches that far, mind, but I happen to have an old M-G catalogue in my files.
    If you're interested in it, just PM me your email and I can send it to you.
    BTW, the C60N was only available in C curve version. Are you sure that the original breaker was a D curve C60N?
    According to the catalogue, it could have been either a C curve C60N or a D curve C60H.

    Incidentally, these breakers are exactly what I have also on my boat - all of them C60N C curve, chillers included, and all original (17 years old) and still working just fine, fingers crossed.
    In fact, coming to think of it, I don't see any reason for D curve, also for chillers.
    I mean, C curve components must withstand a momentary peak of 5 times the nominal current capacity (i.e., in your case, 63A x 5=315A), as opposed to 10 times of the D curve.
    Now, if the spike absorption of your chiller stretches further than 315A and needs a breaker that can take 630A (WTF?!?), there's something wrong with the chiller itself, methink.

    Back to Schneider breakers, the SP designation in C60SP has nothing to see with kAIC, but it means that the breakers are UL1077 compliant (as opposed to the C60BP, that are UL489 compliant).
    Among many other webpages, this one explains the differences a bit more in detail:
    https://www.c3controls.com/white-paper/ul-489-vs-ul-1077/

    Bottom line, imho the Schneider C60SP 63A breaker should be fine, also the C curve version.
    Which would be in fact a like for like replacement of the original M-G breaker.
    If you fit a new one and it still trips, I'd rather be worried about the chiller rather than the breaker.
  5. Pascal

    Pascal Senior Member

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    0BFCFA9A-068C-41C6-82D3-88C944AF3180.jpeg BAE9401B-710B-4AD0-AFDB-2197C992D2A1.jpeg Thank you so much for this detailed post, it is very useful and informative. Years ago, back in the 80s on st barths, I used a lot of MG breakers and panels when I built my house... I had not dealt with these breakers until I found them on the lazzara 84 five years ago and now on the 116

    the three chillers use frequency drives so there is no amp spike when they start as they ramp up gradually

    The boat was built 16 years ago and a number of breakers have been replaced on the main AC panel in the ER.

    interestingly, the breakers for the ER blowers also using freq drives are type C along some large motors like the fire pump and emergency bilge pump. I am going to try a replacement type C

    the cruisair chiller system is a bit sloppy in my opinion as the control box is setup to be fed by two breakers. One 63amp breaker powers two chillers and the other powers the third chiller and the pumps. There are individual breakers for each chiller and pump inside the cruisair box but I wish the system was powered by 4 separate breaker.

    The main panel breaker that occasionally trips is the one powering two of the three chillers making it difficult to troubleshoot. For most of the day, I ve been disabling chiller nr 2 running only nr 1 on that suspect breaker. So far it has not tripped. In a few days I ll start running nr 2 only and see what happens. If the breaker trips it will definitely point to a problem on nr 2

    I ll PM you my email. Thanks again
  6. mapism

    mapism Senior Member

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    Just for reference, no frequency drives in my chillers, whose breaker as I said is a C curve M-G Multi9 C60N, still working fine after 17 years.

    No idea of why someone fitted that D curve Schneider breaker on A/C #1 line.
    Maybe an attempt to fix the random tripping, which possibly was already there in the past?
    Regardless, I certainly see no logical reason for a D breaker on gradually starting motors like yours, considering that C curve ones are fine on mine, whose exact spike absorption I never bothered checking, but certainly there must be some.

    I just sent you the catalogue, maybe check your spam folder if you shouldn't get my email.
    Last edited: Jul 24, 2021
  7. Pascal

    Pascal Senior Member

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    Got it. Thanks!!
  8. Pascal

    Pascal Senior Member

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    I ordered the C curve from Grainger (a big industrial supplier here in the US). Not cheap at $176 but it was in stock.

    turns out that Dayton “makes” these breakers for much cheaper. “On clearance” at $16. Thankfully Grainger list the country of origins on their website: yep, made in china.

    even on my on boat, paying the bill I would not risk it.

    https://www.grainger.com/product/DAYTON-IEC-Supplementary-Protector-5ZVC1
    TahoeJohn and T.T. like this.
  9. MBevins

    MBevins Senior Member

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    Mexico seems to be the "cheaper" build source for this kind of thing.
    I'd have no issues buying Mexico. China for this application, not so much.