House burned down

[robbob2112]

Earlier I stated there was a universal class T holder - drum roll, I was wrong - I know I know you are either thinking "WHAT!! never" or you are thinking "What, again??"

Here are both sizes of the "ignition protected version. There is indeed a pocket that is totally isolated from outside air around the fuse. The cutouts at the ends are for the lugs only, a piece of plastic goes tight up against the fuse itself to make a seal. Probably not airtight, but very close to it.

Interesting note - the only difference the base - the screws on the small one are 2mm closer together than on the large one.

 

[robbob2112]

there is always a risk use a contactor or mosfet i am using mosfet jk bms. havent read about that they fail.
the jk bms has relay contacts to drive some external load so there can be added a NO contactor this will reduce the risk if somebody want to install this.
or install a 2nd bms with a NO contactor.

you have choose the wire and fuse above the maximum load your battery/bms can handle

so in the jk case i would use a 250A fuse with a very flexible 70mm² H01N2-D welding wire, dont know the american gauge or cable type
if a 70V mega fuse is used it will blow at 200% current in 7 to 15 seconds so in this case at 500A

a german guy has tested this. watch it starts at 13min7seconds in the video (activate englisch subs)

maybe a class t is faster so it is a nice to have

he compares the victron mega fuses with the noname. and the noname fuse is better than the victron. the victron fuse does not blow fast its a very bad fuse and very expensive.


well if all fails, the fuse, the bms and the 2nd contactor then your battery build has to past a extreme test if all non flamable materials used in the build can stop the thermal runaway.

This one is a longer version and to destruction

5500amps for the source .

The take away from this is some of the fuses don't completly clear the bridge material, but almost all go off with a bang and sparks when hit with very large current. And most loose their tops in the process.

Seems to be a reason to get the ignition protected class T holder.

When he was testing the victron holder top was not installed, I wish he had done a few with that so we could see if there sparks coming through the hole on the top of cover. With the size of the sparks I would bet enough comes out to spark a gas.


Particularly intersting at this point - 58v 125amp fuse that sustains and arc without being massive current. And it softens its own case in the process.

And I am depending on youtube to translate the captions which were auto-generated so he may be talking about a recipie for strudel.


One thing he does talk about I hadn't considered - When the fuses blow they deposit metal generated soot and particles inside the casing which could easily sustain an arc.


I really need an auto transformer to test the fuses at the right voltage and higher current. I have a step down transformer from an old UPS I can use like @Hedges suggested all by itself.

 

[ksmithaz1]

come on guys, this thread is not for propane storage

We are talking about burning a house down. I would say propane storage would be relevant. Might not be a great idea to put a 200gal tank next to your solar battery bank. YMMV.

 

[Bob B]

I absolutly agree on written instructions - they should be clear and proof read AFTER translation by a native speaker of the final language.

I absolutely agree this is a key point for documentation to be effective.

Fairly early in my career, I maintained mainframe computers for a multinational company ..... One of the smaller mainframes was manufactured in Italy.
The entire manual was written by an Italian who had been taught English. Complex diagnostic procedures were almost incomprehensible.
While it's still possible there could be misunderstandings if a native English speaking person translated the Italian for the manual ... at least it would have been possible to follow the instructions. We were lucky that we had one technician who's was born in the US but who's parents were Italian ..... If there was a major issue with that system we had him first in the call sequence.

 

[_voltmeter_]

so he may be talking about a recipie for strudel.

i can understand what he says
have seen the subs, it is a "ok" translation

but yes if it is a short across 48V, the mega fuse explode and can ignite hydrogen leaked from a damaged cell.
i have ventilation with ups backup in my battery room.

 

[robbob2112]

Agreed, but a 600v fuse used on a line with 500vdc and 30amps shouldn't have a problem so long as the 30 amps is not exceeded.

But, the resistance of fuses does vary by the amp rating, which means heat output varies by amp rating.

From my testing with the class T and Chint fuses the higher the amp rating the lower the internal resistance.

From looking back earlier in this thread where I posted a picture of a bunch of fuses side by side, the larger the higher the voltage rating the larger the fuse. The Class T in the picture are rated 125vdc and 160vdc. The larger is physicaly bigger. The Chint have a way higher voltage rating and much larger. But their internal resistace is higher so more heat loss. But they sit in the holder in open air to disipate the heat.

See

House burned down

Possible solution: BACK UP. This guy is FUSED 🤣 1 on each battery, 1 300amp anl and 1 T class. 🤣 fused Probably had a fire - bad experience Link for the contactor? The MRBF is probably OK, but I get them from Mouser for eaton brand.

diysolarforum.com

Now, all that said - our friend @dianea had a fuse mounted to a DIN rail and looked like screwed to a sheetrock wall verse inside an enclosure and she was kind enough to post a picture of it as a warning - so I was asking for any details she could provide about the fuse itself. As in type/voltage/amps from which we can see why it did what it did.

I suspect from the picture there was a short somplace or more likely the fuse was being run near its amp limits and it heated up like the filament in an old light bulb. and burned the wall and melted whatever the casing it. That looks like a fuse holder that has a flip out door and you put a fuse inside it.


P.S. @dianea - if you have more pictures I would like to see one from farther way showing all the damage, looks like the wire on the right had a melted sheath.

Started a thread with information about the chint fuses with links and data sheets.

 

[DPC]

My best guess is I made this to fit under the dog house of a Kohler electric plant with more available current than I was comfortable with .
Its Phenolic so its old..

I don't think you should be using any fuses that don't look like this...

Probably a big old EL-8 controller and I wanted a local service recipritacal. ( thats poglish language training right there )
I used to do that to a lot of generating plants.
Notice the interrupt capacity..

Don't use Chinese junk.

You cant read that...
Its a common HRC fuse 15 amp.
very simple basic fast fuse with silica sand inside.
The silica fuses into glass in a bad fault prevents fire and all the bad stuff you see with those Chinese fuses in previous video.
Not as fast as a T or J fuse but its not going to cause a fire ever..

 

[_voltmeter_]

see with those Chinese fuses in previous video

there was a expensive victron fuse too, they behave the same and they protect the wiring
you need an additional bms per paralel bank with mosfets or a contactor or both to protect the battery cells from dumping current of the other working paralel banks.

a fuse filled with sand is of course better than a cheap mega fuse

btw. i use chinese junk bms and chinese junk lfp cells with victron junk made in india

 

[DPC]

Fire bad

 

[robbob2112]

My best guess is I made this to fit under the dog house of a Kohler electric plant with more available current than I was comfortable with .
Its Phenolic so its old..

I don't think you should be using any fuses that don't look like this...

Probably a big old EL-8 controller and I wanted a local service recipritacal. ( thats poglish language training right there )
I used to do that to a lot of generating plants.
Notice the interrupt capacity..

Don't use Chinese junk.

You cant read that...
Its a common HRC fuse 15 amp.
very simple basic fast fuse with silica sand inside.
The silica fuses into glass in a bad fault prevents fire and all the bad stuff you see with those Chinese fuses in previous video.
Not as fast as a T or J fuse but its not going to cause a fire ever..

That looks a lot like the vintage fuse on my 1965 drill press.

 

[DPC]

That looks a lot like the vintage fuse on my 1965 drill press.

Ya but I made that fuse holder not that long ago....
Not in the 60s maybe in the past 20 years lol.