I have an Outback e-panel and am using MNEDC-100 breakers on the input and output connected to a Classic 150. Input voltage is around 40-55 volts and output is at 12v nominal. Normal input amps runs around 20 or so, and output up to 85. Since commissioning the system a year ago, the output breaker has run hot - hot enough to burn skin if the terminal is touched for anymore than a brief moment. (The input breaker has always run at room temps, but that is expected because it rarely handles more than 20 amps.)
I assumed it was because I was using slightly undersized wire, 6AWG on both sides of the breaker. Recently I replaced the wire with 2awg between the input bus of the epanel to the breaker and 4awg from the breaker to the Classic. No improvement.
I then thought that perhaps the high heat had damaged the breaker over time, so I swapped breakers with the input breaker, again with no result.
Assuming the heat doesn't damage the breaker assembly at some point, there is also a .3v drop across the breaker when it is hot which means the Classic never 'sees' the correct voltage of the battery - unless the breaker is cooled down. I could adjust the Classic to compensate, but the voltage loss in the breaker is obviously amperage dependent, so a fixed adjustment on the Classic isn't optimal at lower amperages.
I'm out of ideas. Any thoughts from all the wise ones on this forum? Shouldn't a 100A breaker be able to handle close to 100A without significant heat issues?
Thanks in advance!
Mike
You might have a faulty breaker.
You might have a loose wire connection to the breaker.
I would torque down the terminal(s) on the breaker. It is a normal post install recommendation that you re-torque all wire connections to compensate for cold flow in copper wire.
If you can borrow an IR non contact thermometer you can easily see if it is internal heat or terminal heat.
Just a couple thoughts on tracking down the cause.
Tom
Thanks Tom. I could imagine one faulty breaker, but it would be a stretch to think that I got TWO bad ones, though I suppose not impossible. That's what I was thinking when I swapped it with the input breaker, but it didn't seem to make much difference. I've torqued and re-torqued them as well - they're on nice and tight. These breakers take lugs (which are soldered onto the wire), so there isn't much copper flow to happen there.
The sequence on the breaker post, from breaker outwards is nut, washer, lug, washer, nut. I couldn't find any other instructions online as how to connect the lugs to the post, so this was my best guess for greatest surface area from lug to post. Do I perhaps have them mounted incorrectly?
Unfortunately, I don't have access to an IR thermometer.
Mike
What metal are the washers and nuts? Stainless steel has higher resistance; maybe that is part of the problem? Just guessing.
Good thought. Unfortunately, they're whatever came with the breaker, so I would assume that it's suited for this purpose.
Mike
I use the exact same breaker. Will check the temp today. Not something ever looked at it.
Quote from: mofawayesu on December 02, 2014, 09:21:57 AM
The sequence on the breaker post, from breaker outwards is nut, washer, lug, washer, nut. I couldn't find any other instructions online as how to connect the lugs to the post, so this was my best guess for greatest surface area from lug to post. Do I perhaps have them mounted
Should that not be breaker post, lug, washer, lock washer then nut ?
Why is there an extra nut and washer between post and lug?
Dgd
If the input breaker is also running hot, with "around 20 amps or so" then there is something terribly wrong ...
What is the wire gauge on the input and output of each of these breakers?
Generally, in my opinion, soldering lugs is a bad idea. IMO, lugs should really be crimped only, with a good crimper. Some people crimp and solder, but, if a crimp is good, no solder should be needed.
Use MNEDC breakers with currents in the 70 - 80 amp range, and there is very little heat on the breaker studs, lugs or wires.
My opinions, FWIW, Vic
did you use the lug type shown on the right side of this page?
https://www.google.ca/search?q=copper+lug&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb&gfe_rd=cr&ei=7yJ-VJarFcyV8Qe3lYHIDg
Following up on Vics' question, did you solder them without crimping?
dgd, that's what I wondered too. The breaker comes with no lockwasher, which I would have expected - it's just two standard washers and two standard nuts. I thought about trying the order of what you suggested, but the amount of metal surface at the base of the post itself is quite small - maybe less than half that of the included washer, so it looked unlikely to me that that was what was intended - especially if it was to carry 100A. I assumed then that one nut was supposed to be locked tight to the post providing the base for the lug above it, but I couldn't find any documentation to say one way or another.
Vic, the input breaker runs cold, no problems there. Input breaker: 6awg both in and out. Output breaker: 2awg out (from breaker to epanel), 4awg in (from Classic to breaker).
Good to hear that yours run 'cold'! Good thought on crimping them - it's because I don't have access to a crimper (I'm in west Africa and good tools are hard to come by!) that I'm soldering them, but maybe I should reconsider and go looking for one. Fwiw, the original cables I had on the output breaker were crimped-lug 6awg that I had been given as salvage. These also had a heat problem. I presumed at the time that the problem was wire gauge, but the temp was definitely hottest at the breaker stud and was not evenly distributed along the length of cable, so I'm suspecting that the wire wasn't really the culprit.
Btw, what order do attach your lugs, nuts, washers?
Westbranch,
Yes, I'm using copper lugs as shown. The ones I have access to are oversized for these lugs (3/8" rather than 1/4), but they're washered down so there's lots of surface area to make the connection. All connections on the output breaker are soldered at this point because I don't have access to a crimper. However, the former 6awg cables that used to be on this breaker DID have crimped 1/4" lugs on them, but it was with these cables that I first found the breaker running so hot.
I'm in west Africa and good tools are hard to come by!
Do you have a good battery service depot/retailer reasonably close?
They should have good crimper if they make up battery cables and such. How reliable is the mail/parcel delivery? A lot of us over here get our specialty tool delivered that way as we are more remote than some think... even Ebay....
Thanks, mofawayesu for the added info.
We all cam emphasize with you being (perhaps) in a remote area Continents away from North America where many of these items are made.
For these higher current levels, run a physically larger breaker, usually. This E-Frame breaker is sometimes used on e-Panels, but usually as a 125 A battery breaker. They have 3/8" studs, and accommodate large cables, well.
Your output cable sizes seem quite adequate to me, for copper conductors. But, to nit-pick a bit, a 100 Amp breaker is a bit too large for #6 AWG, even if the wiring is in "free air". If these cables are inside the e-Panel ONLY, then it is probably OK, and might even have been provided by MidNite. If these input cables are in conduit, then #6 is a bit too small -- actually, the breaker is a bit too large for that cable. Breakers (and fuses) are to protect cables and wiring from risk of fire. Breakers are handy switching devices, as well. Nit-pick over ...
I have run the MNEDC 80, and 100 A breakers on occasion, and do not recall any over heating. But, your ambient temperatures may well be higher that those usually seen here, and normal breaker heating, and heating normally seen from the breaker itself and from the small voltage drop at the lug is a temperature rise, above ambient temperature. Still, approaching burning the skin temps really seem excessive to me.
The nut/washer sequence should be the same as supplied on the breaker -- nut on the bottom, one washer, lug, washer and the nut on top. Believe that this is as you described. This spec sheet shows the stud with nuts and washers:
http://www.midnitesolar.com/pdfs/CA1-X0-17-767-321-L.pdf
Believe that the MNEDC breakers have been changed a bit from the following drawing (now recall that they have a formed metal "platform" for the stud mounts. This design (if recollection is correct for the EDC) should allow more torque to be applied to the nuts, without the concern of over-torqueing the nuts and perhaps cracking the plastic breaker case ... just guessing.
The MidNite breakers are really top-notch, are well rated for our uses, and are very inexpensive, and quite compact.
All just my opinions. Good Luck, Vic
That first nut to go on is to hold the stud to the breaker. If it is not holding that snug I think it will get hot as it is not a good connection. They can break, too so it cannot hold it properly.
Just thoughts from experience
Tom
Well, i can somewhat confirm the heat issue. I turned off our array until noon, and its just now run at 60A for about 30min. The classic panel mount breaker before i started was at 20C ambient. It now reads 45C in the top corner nearest the post, and 30C in the other three corners. The top post is around 40C, so it appears that the breaker is generating heat in that top outer corner. I can fully believe that running this at 80A would get quite hot.
None of the other breakers are more than tepid, and they are all carrying amps at the moment.
I also have the nut, washer, lug, washer, nut config, but based on the IR readings fairly sure that the heat is internal.
Mofawayesu,
It appears you have the breaker wired correctly and as VIC detailed.
I took a pic of my MNDC box with 100A, 80A and 60A breakers and indeed the 100A type at the front has two nuts and washers. Note the 80 A behind it has a different stud mounting.
The cables to the breakers are multi-finestrand #4 and the lugs are deeply crimped on the cable.
I know you have probably checked this but you say yours are soldered but you are very sure its a good solder joint? I agree with VIC and would recommend you also deep crimp the lugs.
ZB,
I was surprised after your heating confirmation so I went to check my breakers. The 100A one was outputting 74A to the battery and the 80A breaker had 34A output.
I felt both and they were at ambient temperature which is about 18degC.
Then I realized they were all Outback breakers as supplied by Able Solar. I thought these were identical to the MN breakers but maybe not.
dgd
dgd,
Thanks for the clear photo. The second and third breakers are the style that has the formed metal "platform" thing that I was trying to describe before. Am certain that those are the Carlingswitch breakers that MidNite sells as the MNEDCs. That is either a newer design, or perhaps just used on MNEDC breakers with the high current ratings. This style may dissipate heat better, and would allow one to torque the nuts tighter (IMO).
Have used the MNEDC 80. or 100 A breakers on a Load Bank, and sure do not recall significant heating of the breakers or the terminal studs. Am in town now, so cannot confirm the design of those EDCs or the heating.
zonblue, thanks for running tests. IR Thermometers sure do come in handy in many applications. Vic
Mine is 100A, without the plates, from naws last year. I cant see the sticker side, but i have 80A one just like it which is labelled,
CA1-X0-17-775-321-L
AMP 80
MAX Volts 150 120
hertz dc 50/60
delay 36
trip amps 108
circuit 80
mexico 1239R
The hot spot is near the LINE terminal, with the battery on the LINE side.
Zoneblue, I'm glad then I'm not the only one! My breaker is definitely more hot on the line (battery) side than the other - like yours. I'm curious if you're also seeing .3-.4 vdc voltage drop across the breaker when it's hot as well.
Vic/dgd, Yes, mine are the 'older' style without the platform. They were purchased in Canada 18 months ago.
On the two breakers I have, not all the posts were snugged up tight with the first nut, but that was one of the first things I noticed when I started to try to fix this, so they are now. It looks like the new style only comes with one nut, so this shouldn't be a problem I'd hope.
By 'deep-crimp', are you suggesting one of those hammer/vise type crimpers? Those are small enough I could get someone to bring one over on a plane someday. Unfortunately, battery shops that would have the right tools here are several hours drive away.
Vic, you're right about the breaker/wire size mismatch. My intention was to eventually replace those #6 input cables with #4 to match the breaker, but at the time of wiring the epanel, I didn't have any more #4 cable, so used the #6. Thanks for the reminder!
Westbranch, it would be nice if parcel/mail were reliable here! Hardly anyone uses the postal service here for anything but paper mail because anything of value is so consistently stolen.
We have enough contacts with people coming this direction that we can usually get something handcarried here on a plane in a matter of 2-3 months or so - you learn to plan waaaay ahead!
This is a small (half briefcase size) hydraulic crimper. Ebay, Ships from Canada
Hydraulic-Crimping-Tool-Kit-8-Ton-Electric-Wire-Crimper US $70.00
http://www.ebay.com/itm/230847642864?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649
seller SAROHS http://www.ebay.com/usr/sarohs?_trksid=p2047675.l2559
Hexagonal die sizes (mm2) â€" 4,6,8,10,16,25,35,50,70
Hexagonal die sizes (converted to AWG) â€" Ranges from 12 to 2/0
It has worked well for me, on a 48V system which has lower currents than 24v systems (1/O wire)
here is another link at ~ $35
http://www.ebay.com/itm/10-Ton-Hydraulic-Wire-Battery-Cable-Lug-Terminal-Crimper-Crimping-Tool-9-Dies-/380780092529
I also got the one Mike listed, and it works fine, just use the smaller of the dies when you do the size conversion. Some 'straddle' the AWG conversion number and the larger one will not crimp tight enough.
I will check the voltage drop next sunny day. I wonder if rewiring in the reverse direction will make any difference? They are supposed to be unpolarised, but hey, it is in backwards afterall. If its anything like tenths of volt, thats just ridiculous.
Mofawayesu,
I don't think there should be any heat associated with the breakers. Just that small voltage drop of .3 to .4 volt at 40 amps would mean 10 watts of power being dissipated
This would lead to a real hot breaker in very little time and definitely poses a fire risk.
If its the breaker making the heat then its faulty, likely burned up switch contacts making a resistance to current flow. The only solution is to replace the breaker.
If the cable is hot then it could be a loose connection, anything from the lug not being tightly bolted down to a badly contacting cable inside the copper lug.
I would recommend changing the cable with one that has the copper lugs crimped.
If you do not have a crimping tool then use a flat faced metal punch (about 1/4 inch or 6mm face) and use a use a sledge hammer to drive it into the back of the lug to create a deep deformation of the copper lug into the cable.
Do not solder or heat the lug/wire.
If after trying the new cable, making sure it is real tightly connected to the breaker, there is still heat coming from the breaker then the breaker needs replacing. Until you get a replacement just forget about the breaker (its useless anyway) and wire the circuit without it. If you have a fuze available (T class type 100 to 200 amps) then put this in circuit for safety.
dgd
Thats not the conclsuion i get to dgd. My breaker was criimped correectly from the word go, and has had a very gentle life. It being the silly season, i dont know when i get to it, but will definately check the other unused breaker at some point, and also a polarity swap.
When you felt the temp on yours, did you check the area near the line terminal? And was the one carrying 70 amps the one with the plate or the one with out?
I seem to recall a thread previously about these breakers, but cant find it...
ZB,
After reading your earlier posting about breaker heating I have almost continually monitored my breakers in MNDC.
I have felt all the cables and connections and absolutely no excess heat.
The three Carling type surface mount breakers are also just at ambient on both terminals and the back and body sides are cool.
The closest one in my pic is 100A and uses the two nuts on each post. Today at 1pm there was 62A at 28.7v through it and I could not detect even the slightest heat and no voltage drop over the breaker terminal posts. Cable is #4 to Classic 150.
The middle one is 80A and is the flat plate type post with one nut/lockwasher. It was at 29A at 1pm, 28.7v and again no voltage drop. Terminals and cables were cool at ambient.
Cable is #4 to Classic 250.
These 3 breakers as mounted in the MNDC are not tight together, there is a small air gap between each..
All 3 have commoned together outputs using a solid copper bar with the output cable on the 100a breaker using a short length of #2 with connects to +ve input on 250A breaker post that connects to bank via 1 metre of #0/2
All of these cables and connectors run cool at ambient. I cannot detect excess heating anywhere in this connection chain of cables.
But all of this is just as I expect it to be.
These breakers are not AFAIK thermal types.
I just can't understand how a breaker should heat up as that means resistance which nobody wants between Classic output and battery bank.
dgd
Well all i can say is what i measured. It also makes no sense to me, because these breakers are a magnetic hydraulic design. If and when we get to the bottom of this perhaps ill sacrifice one to a biopsy.
Do you have yours LINE to battery, or LINE to classic?
Yes, these PM MNEDC breakers are Magnetic-Hydraulic types.
There is a solenoid winding for the magnetic function of the breaker, this, the contacts, and all of the interconnections DO have some resistance. But agree with dgd, that a number of watts dissipated in the breaker should not be required, and would result in quite a lot of heat to dissipate ...
Begin to wonder if these breakers are real MN -- Carling units ...
FWIW, Vic
Quote from: zoneblue on December 04, 2014, 01:31:15 PM
Do you have yours LINE to battery, or LINE to classic?
9:34m and 47.5A through 100A breaker and I cannot detect any warming. Maybe I need to get an IR thermometer to be 100% sure but the finger feel test shows nothing.
I didn't think polarity line vs load mattered with these but in my setup the LINE is to battery and LOAD to the Classic.
dgd
QuoteMaybe I need to get an IR thermometer to be 100% sure but the finger feel test shows nothing.
If the pad of your finger can't feel it, the back, near your nail, is very good for checking small thermal differences. BUT check with the front of the finger first, 'cause you can really burn the back side very easily.
Well, regardless of the final autopsy, it looks like I should get another breaker! I have a connection from N.America coming in January sometime who could bring what I need. It sounds like the 'new-style' ones would be the better bet, seeing as both of my 'old-style' ones have the same problem. Suggestions as to where to get them to ensure getting the new style?
Re crimpers - thanks for all the link suggestions. By the lack of comments on the idea of getting the hammer type of crimper, I'm assuming you all don't think much of them.
These guys have good prices and reputation.
Northern Arizona Wind and Sun,
http://www.solar-electric.com/
Quote from: mofawayesu on December 07, 2014, 09:13:13 AM
Well, ... It sounds like the 'new-style' ones would be the better bet, seeing as both of my 'old-style' ones have the same problem. Suggestions as to where to get them to ensure getting the new style? ...
Hi mofawayesu,
Many distributors and dealers do not rotate their stock. Have checked the inventory of the MNEDC breakers stocked here, and there does not seem to be a high degree of correlation between the new style with the "platform" and a single nut, and the current rating of the Carling breakers, or for my guess of what is the Date Code on the breaker's sticker.
It IS quite possible that the newer, high current-rated breakers will generally have the platform, but the stock from an order from early this year, there is a mix of styles for a given amp-rating.
Generally, have had good service from Wind-Sun:
http://www.solar-electric.com/installation-parts-and-equipment/midnite/cipr1/stfubr1/pamodccibr.html
So HOPE that you will be able to find what you are looking for.
Can you please confirm that the hot breakers are Carling brand? Good Luck, Vic
Mike,
PM me your address and I will send you a few 90a 80vdc breakers if you want to try one on the output. I ended up with a few hundred of them, I have never had a problem with them heating up.
Fwiw, I installed new breakers, bumped up the size of the cables to to #4 and still have the same problem with heat/voltage drop. There's GOT to be a bad connection somewhere but I can't track it down for the life of me. Sigh.
Maybe invest in an IR thermometer or thermal imager? Scan the likely points/connections.
Ralph
I confess i forgot about this thread, and have had the disco apart since your OP, so could have studied this more closely. My feeling at the time is that there is a real issue with some batchs of these breakers. And im wondering whether polarity is a factor or not. In my next NAWS order ill get a spare, and compare them. Its summer here now so easy to check 60A through them. Will keep an eye.