"Switch Rating" of MN Breakers?

[Vic]

Searched around this Forum, and the MN Site,  but was unable to find reference to using various MN/CBI Breakers as switches.

For example,  the DIN-Rail type compact breakers-- MNEPV 150 V.  It is noted that they are Hydraulic/Magnetic style,  but they lack the "over-center" feel of the MNEDC panel mount type breakers.

My query has to do mostly with the mechanical cycle rating of the two above breakers.  Seems to me that the EPV unit simply cannot endure nearly as many mechanical cycles as the EDC -- it does not seem nearly as robust.

I looked for DATA on these on the MN site and there was almost nothing in the way of specs.  Looked at the CBI site,  and  a bit more data,  but seems without being a registered customer of CBI,  the next level of data was not avail.

Can MN provide any mechanical cycle life spec?

It is just my personal feeling that the EPV breakers should be used in Combiner Boxes,  but NOT as the OCPD at the input and output of a CC,  where the number of cycles would be much greater than for a combiner. That is,  I would only spec the MNEDC breaker for use in the power room,  vs the EPV on the roof, in a combiner.

AND,  YES,  whenever at all possible,  I dry-switch the breakers -- under no DC load conditions.

Thanks,   Vic

[boB]

Vic, we will find out this info for you.

Robin just had dinner down at SPI with the  CBI  Guy but we talk with them regularly of course.

I would think that breaking them "dry" as you say would also be a good thing, but I don't know
how much better.   Maybe their springs will sprung or something ??  Will  find out.

boB

[Vic]

boB,  THANKS  for the rapid response.  Have Fun,  Vic

[laszlo]

FYI

Per Robin's post in this forum (http://midnitesolar.com/smf_forum/index.php?topic=41.msg257#msg257) the CBI breakers are rated for 5000 cycles.

[Vic]

Hi laszlo,

Thanks for reminding about the linked reply.  That is useful info.

My question had an additional aspect,  regarding the mechanical life,  vs trip-cycle life,  or switch-cycle life,  at rated load current.

5000 cycles is quite a few.  It would be surprising to me if the MNEPV -- DIN-Rail DC breaker --  would endure that number of cycles.  This is just a personal opinion,  without pesky data getting in the way.

Anyway,  whatta I know?!  Thanks,  Vic

[laszlo]

Hey Vic,

The post from Robin also stated the 5000 cycles for the CBI breakers are under full load.

5000 is a lot, but not such a large number that it could not be verified  -- they have these machines that can toggle a breaker or light-switch switch on and off repeatedly at UL certification labs.

By he way, if you purchase a Midnite PV combiner box, included in the package is a writeup by Robin about the kind of tests they are doing for UL.  Maybe there is an online version as well, not sure.

Hi laszlo,

Thanks for reminding about the linked reply.  That is useful info.

My question had an additional aspect,  regarding the mechanical life,  vs trip-cycle life,  or switch-cycle life,  at rated load current.

5000 cycles is quite a few.  It would be surprising to me if the MNEPV -- DIN-Rail DC breaker --  would endure that number of cycles.  This is just a personal opinion,  without pesky data getting in the way.

Anyway,  whatta I know?!  Thanks,  Vic

[Vic]

Hey Vic,

The post from Robin also stated the 5000 cycles for the CBI breakers are under full load.

Hi Lasxloj,

Yea,  that was the point that I was trying to make.  As,  the way I use the Panel Mount,  and DIN-Rail breakers is to switch them WITH NO LOAD,  such that the cycle life at rated load current may well be a low number.

CBI does have a set of specs for cycle life with and without rated load (am just guessing,  but how could they not).  There is a target that they have aimed for,  and some cycle life test data that confirms the desigh.  AND,  for any large manufacturer of such items,  there should be QA tests that confirm production on an on-going basis,  using  lot-sample analysis.  Weather they choose to share this data with the likes of folks like me,  could be another thing.

This may be viewed as simply a rhetorical interest on my part,  but would like to know more about the parts that am recomending and using.

Think that this beaten horse is getting a bit tired.  Thanks again, laszlo.  Vic

[Halfcrazy]

Straight from our CBI distributor when I talked to him in Dallas at SPI. The CBI breakers are good for 10,000 or more switches under partial to no load and 5,000 or more under full load rating. We have sold millions of CBI breakers and I can count on one hand with fingers left over the failures we have had. Rony the distributor for CBI is in Pennsylvania and sells to a lot more than us and he says the same thing they just do not break.

The Over center thing you mention is just part of the spring or snap action it has to open fast to help extinguish the arc. I have a 150vdc Din rail breaker here that is on my lister and I always open it under load it runs a VOC of 195vdc and an operating voltage of 135vdc and 60 amps. I have been using this for about 6 months and have opened it a few dozen times and it works just fine.

Ryan

[Vic]

Hi HC,

Thanks a lot for the data.  5000 cycles is really enough for me.  10K is even better,  of course.

Did not mean to slight the DIN breakers.   Just that they are SOOO compact,  hard to imagine getting the function and cycle life built into that small package.  I have never had any problems with any of the MN CBI breakers,  just hate to hurt hardware.  So this info helps me feel better about using your line of "DC" breakers as switches,  too.

And on the over-center function or feel of the Panel Mount breaker,  Have always liked the feel of these,  just a preference.  But,  these PM jobs are larger,  and so seems that there is a bit more room inside to do the function well.

Thanks again Halfcrazy for the data,  Vic

[Robin]

Both the panel mount and the din rail mount breakers must pass the 5000 times under full load. They also must pass some really bizzare short circuit tests. We had to pass about 2000 amps through the little CBI breakers at 165 volts 50 times before they would give us the 150VDC rating. Make sure they aren't hooked up backwards in a case like that though. It will fail on the very first time you open up the breaker.
Both breakers are very high quality. Use whatever suits your fancy. If anything ever breaks, just give us a call for a free replacement. That just doesn't happen very often. Maybe once a year.
Robin