Author Topic: At What Points Do Breakers Trip?  (Read 114 times)

finalman

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At What Points Do Breakers Trip?
« on: October 12, 2017, 05:57:26 PM »
Just wondering at what point the Midnite breakers and I guess all breakers in general trip?

I ask this as i'm getting MNEPV30's breakers to use with my KID's. Now the KID's max output is 30 amp and the breakers are 30 amps. So if the KID's are maxing out and outputting 30 amps will the breakers trip?

Vic

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Re: At What Points Do Breakers Trip?
« Reply #1 on: October 12, 2017, 06:56:56 PM »
Regarding Trip current verses Handle Rating,  not all breakers are the same.

All MidNite DC breakers are designed to run continuously at the handle rating (the current value marked on the front of the breaker).

The MNEPV breakers that I've seen also have a Trip current value on the sticker on the side of the breaker.   Of course,  there are various curves that show the time for the trip,  verses time.

30 amp MNEPV breakers should be fine on a KID CC,   as long as the cable Ampacity meets or exceeds a 30 amp rating at 70 degrees C (or less  --  this is easy to do).

FWIW,    Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

ClassicCrazy

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Re: At What Points Do Breakers Trip?
« Reply #2 on: October 12, 2017, 07:16:40 PM »
I have had some Midnite breaker trip before it's  rating - the 60 amp mneac  when it was getting close to 60 amps . I needed a larger breaker for that so replaced it with 100 amp MNEDC and not problems . First one mentioned is panel mount and maybe had something to do with wires in screw clamp on there - though they were tight as I could make them. The MNEDC has 1/4 inch studs so better connection for sure.

But I have a MNEAC 20 amp breaker in and limited the current above 20 amps - I think like 23 or 24 and it holds okay - of course PV was making fluctuation in current too so not steady .

Guess you will find out - if you have problem you can always current limit to a point just below where ever it trips but you will probably be okay .

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

finalman

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Re: At What Points Do Breakers Trip?
« Reply #3 on: October 12, 2017, 08:29:35 PM »
I plan on using them for the battery connection so lets assume that the breaker does trip and the KID looses battery power but the solar is still connected and live. Will the power coming in from the panels damage the KID? and is this the same for the Classic's?

CDN-VT

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Re: At What Points Do Breakers Trip?
« Reply #4 on: October 12, 2017, 10:49:32 PM »
I plan on using them for the battery connection so lets assume that the breaker does trip and the KID looses battery power but the solar is still connected and live. Will the power coming in from the panels damage the KID? and is this the same for the Classic's?
I would say yes in that scenario. So the KID has it's own internal fuses & I would breaker the battery output  @ the battery side for the rated Wire you use . So the lenght is 25-30 feet & for no wire loss (Voltage drop ) it calls for 8 gauge AWG , your breaker  is for wire size & the kids fuse is for the kids protection . Same as if your feeding solar panels  into a combiner , you fuse or circuit breaker the limit for the wire  size  & let the kid 30 amp fuse look after the solar . If you use clipper function , than the fuse sizing will change in the KID to protect the internals .

It's NOT good to loose the battery to the KID  and have panels go full VOC !!

VT
« Last Edit: November 01, 2017, 11:40:43 PM by CDN-VT »
Canadian Solar 350W 37.6 VOC  30.6 VMP 8.22 ISC 7.87 IMP ,-15 c +30c max  4 strings in 2 in Series for 24v Classic 150 -1020 Ah  Freezers & fridges ~~~ Second Array same panels of 3sx3 parallel for 24 V Classic 150 -440 Ah Outback Barns & out blds.
48Vdc almost done.

ClassicCrazy

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Re: At What Points Do Breakers Trip?
« Reply #5 on: October 12, 2017, 10:53:52 PM »
Shouldn't hurt anything - if the battery connection opens up the the controller will shut down. The PV if sized correctly for voltage so open circuit voltage should not hurt anything in the controller .  I would think if it did there would be lots of comments in the forums here about blown controllers - I am guessing I have probably shut off Battery before  PV in the past even though I usually try to shut off PV first and then Battery when working on something.
Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

CDN-VT

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  • Thats a C/V-107 pulling a barge on candled ice. ^
Re: At What Points Do Breakers Trip?
« Reply #6 on: October 14, 2017, 12:14:10 AM »
Shouldn't hurt anything - if the battery connection opens up the the controller will shut down. The PV if sized correctly for voltage so open circuit voltage should not hurt anything in the controller .  I would think if it did there would be lots of comments in the forums here about blown controllers - I am guessing I have probably shut off Battery before  PV in the past even though I usually try to shut off PV first and then Battery when working on something.
Larry
I was told from the Gent who repaired my KID from a leaking cap , I was asked if I had shut off the battery breaker before the PV breaker /fuse . Thats when I was told that this could of smoked the cap ??

Just stuff I heard from the repair tech @ Midnight ,Mr S .

VT
« Last Edit: November 01, 2017, 11:41:38 PM by CDN-VT »
Canadian Solar 350W 37.6 VOC  30.6 VMP 8.22 ISC 7.87 IMP ,-15 c +30c max  4 strings in 2 in Series for 24v Classic 150 -1020 Ah  Freezers & fridges ~~~ Second Array same panels of 3sx3 parallel for 24 V Classic 150 -440 Ah Outback Barns & out blds.
48Vdc almost done.

ClassicCrazy

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Re: At What Points Do Breakers Trip?
« Reply #7 on: October 14, 2017, 10:38:40 AM »
Well I would take the advice of the tech guys who have the experience.
Although you would think if it blew caps from shutting off battery before PV  these things would be blowing all the time and would get the fix to stop that from happening at some point in revisions.

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Robin

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Re: At What Points Do Breakers Trip?
« Reply #8 on: November 01, 2017, 02:29:43 PM »
There is no required sequence in turning off breakers to the Kid or Classic. The charge controller may continue to operate for some time if you shout off the battery breaker since it is already powered up from the PV. This doesn't hurt anything. Going above the VOC rating can do damage though.
Robin Gudgel