Anyone know of good compact DC fuses?

[liveforphysics]

Anyone know of a type of good compact size DC rated fuses?

I'm looking for something rated for around 125vdc and around 200amps.

I know DC fuses are much harder to design and need extra length and sand inside etc to absorb energy and break the arc, but everything I'm finding seems to be comically huge like a hot-dog, and I've got very little room to place it.

Anyone know of anything good out there? Not needing a fuse holder would also be very nice.

[gensem]

One week looking for one, still no hope. I would settle for a 125vdc 100a in a blink, but even that is not that comum.
But I think the worst part to find is a decent compact holder.

[gensem]

best I could find so far (price/amps)

http://www.grainger.com/Grainger/FERRAZ-SHAWMUT-Fuse-4ZAC3?Pid=search

but still could not find a holder out of the shelf.


specs
http://www.ferrazshawmutsales.com/a3t_a6t_series.htm

[ZOMGVTEK]

As far as fuses go, thats a good looking fuse.

$30/ea. is a bit steep for limited protection. I suppose if you are running huge wire and have a battery system capable of thousands of amps its a good idea. I'm just going to continue with my 10 AWG fusible link. It should disappear, eventually, right? How bad can it be?

[bigmoose]

Luke when I was designing similar stuff, here are the two data sheets I saved. They are forklift fuses, each data sheet has a fuse suitable for over 100VDC.

EV pars fuse 400 Amps 100VDC for 25bucks
http://www.evparts.com/products/street-vehicle/fuses--and--circuit-breakers--dot/fuses---street-vehicle/fu9531.htm

Nice internet fuse supplier
http://www.discountfuse.com/Ferraz_Shawmut_Mersen_Fuses_s/20.htm

[gensem]

many thanks for the link bigmoose
they have a good price

[zombiess]

Little off topic, but why wouldn't you use a high amp fuse designed for car audio? They are 12V DC, but does the voltage really matter on a fuse? I thought only the current it was passing mattered much like the ampacity of a given wire gauge.

Please point me in the right direction here if you would be so kind, a link to an explanation would be fine. My brain isn't working very well right now and I can't for the life think of a good reason.

[ZOMGVTEK]

The 12V fuse will probably blow, but it would arc for a dangerously long time as the fuse eats itself.

100VDC is NOTHING like 12V. It's even harder on switches and fuses than 120VAC. Lots of 120VAC switches won't stop 100VDC. And most 12V fuses won't stop 100VDC in a reasonable period of time, or safely. Generally you would want a reasonably reliable and fast acting fuse in an application like this, and you simply would not be able to count on a 12V fuse to do the job well.

[gensem]

im sure gurus ll explain it much better.
but to put in a simple way, if you use, lets say 90vdc in a 12vdc rated fuse, the energy ll keep flowing even after the fuse was blown. Most people think energy cannot travel thru the air, but it actually can if the wire ends are not far.

[bigmoose]

Since we are all here to learn I went searching for some more information on DC fuses. The attached article is pretty good to get us started on DC fusing. It explains what type of fuses should be used for PV installations and why using car fuses is not necessarily a good choice. Choice snippet:

Are ac and DC Fuses the Same?
Direct currents are very difficult to stop or interrupt when compared to alternating currents. Alternatingcurrent sources reverse the flow of current 120 times a second (in some locations 100 times a second on 50 Hz systems). Each time the current reverses, it goes to
zero in magnitude. A zero current is very easy for a melting fuse to stop or interrupt—it is already stopped, and there is no force trying to sustain an arc across the fuse element. DC currents, as the name implies, are currents that travel in one direction only. They do not reverse. Fuses bear the entire burden (with no help from the current) of acting to stop these currents. The internal elements of a fuse must react to an overcurrent condition (usually by melting) and as they react, they must do so with enough capability to interrupt the current from flowing while extinguishing any arc that might form. DC fuses are relatively sophisticated devices that have many different internal elements that must work together. The complexity of DC fuses makes them cost more than ac fuses that may contain only a single, meltable link.

[regmeister]

These terminal marine fuses have 58V max rating, so would be ok for some applications, just not this one.

http://bluesea.com/category/81/21/produ ... erview/378

They offer a variety of fuse products, including the big class-T terminal blocks.

http://bluesea.com/category/81/21/productline/130

[peterperkins]

Luke as you know Hybrids have a selection of DC HV fuses.
One for main power ~100A and one for spur to DC-DC converter ~20-30A are they not suitable?

Ron at Hybrid-battery-repair.com sells 100A Insight fuses for around $15 they are a reasonable size.

Littelfuse who make the OEM Honda Hybrid fuses can sometimes be prepared to sample fuses I've had a couple of 200A ones off them for projects.

[jdb]

Cooper/Bussman and Ferraz-Shawmut have supplied us with UPS fuses for years. They make DC-rated fuses that will fit your req's, but they are spendy. Maybe not too spendy for racing. Each of these are semiconductor fuses, very fast acting. Each of them have proper mounting bolt blades for attaching to bussbar, thick cables, etc.

The Grainger catalog has quite a variety to choose from. These are a few that jumped out at me in the 200A fast-acting category:

FWA-200A 200VDC, 200A, Retail $53/ea 2.5" long http://www.grainger.com/Grainger/COOPER ... Fuse-4XC82
Ferraz-Shamut A30QS 200A, 300VDC 3.125" long, Retail $42/ea http://www.grainger.com/Grainger/FERRAZ ... Fuse-6UVF3
Ferraz-Shamut A15QS 200A, 150V, 2.75" long, Retail $30/ea http://www.grainger.com/Grainger/FERRAZ ... Fuse-6UVE0

[bobc]

If it's for temporary & stationary use (e.g. to protect a prototype in the lab) try making a water fuse. I may be some way off here as I haven't done this for 30 years but here goes - use ordinary prototyping stripboard, the stuff with holes every 0.1". About 1.5" length and 6 or 7 strips wide will do what you want but you have to immerse it in water. This fuse blows very fast when enough amps cause a steam jacket to form. The length and holes break up the arc to stop the DC. Corrodes after a couple of weeks & ovbviously can't be used on anything mobile ;^)
edit - you want 200A - make it twice as wide..... soz

[gensem]

Luke,

Were you able to find smaller fuses, or maybe fuses that dont need holders?

Thoses Ferraz-Shamut are nice but the holders are 5"-6" hella big and heavy...


Anyone else has a source for 125vdc 200a tinny fuses?

[NeilP]

No idea..but i can show you my first blown fuse in over 2700 miles

viewtopic.php?f=7&t=33321

[zombiess]

No idea..but i can show you my first blown fuse in over 2700 miles

viewtopic.php?f=7&t=33321

When I ran those style holders they always got hot and melty too. I switched to some cheap car audio 60A fuses. Only rated for something like 20V, but I figure if my 100+V pack shorts the fuse should vaporize pretty well and stop the flow. Sounds like I should do some destructive testing to see how they react

[NeilP]

I know these fuses are designed to run at their rating, but I have been consistently running at 20% or more above that, and it has handled it for a long period, so yes, some destructive tests to see when your fuse does actually blow sounds like a good move

[ryan]

Any one have a better answer for this? I just got a comically huge Maxi 80A fuse and inline holder. I don't have enough room for this monster and am hoping someone else has figured out a smaller alternative.

[liveforphysics]

Any one have a better answer for this? I just got a comically huge Maxi 80A fuse and inline holder. I don't have enough room for this monster and am hoping someone else has figured out a smaller alternative.

This was the best type I've seen. Class-T fuses.

http://bluesea.com/category/81/22/produ ... erview/136

[ryan]

Wow! $40/ea! That's more than I paid for Method's HVC board! And I'd have to buy two to make sure I have a spare. I may just solder up my Maxi fuse with some heat shrink in the meantime. At least I have a half dozen of those.

[ryan]

Well soldering up my Maxi fuse is a bust...

And my inline holder is larger than a Battery Medic. I just may have to bite the bullet on some of Luke's fuses. Thankfully McMaster has them for $20ea. But still ... $20 for a fuse!

[acuteaero]

Did you consider the ANN/ANL/CNN/CNL fuse? It's not rated high enough voltage wise for the application Luke was discussing, but some versions are high enough for most ebikes (80v). They are a lower profile and lighter weight than the class T. Often used in forklifts, golf cars and other battery powered things. Search eBay for ANN fuse. There is a seller with many values of fuse for pretty reasonable cost.

As well, the smaller <70a class t fuses are cylindrical without lugs and require blocks.

I have used these maxi blade fuse holders in the past, look a bit more compact than the one you pictured. http://www.powerwerx.com/fuses-circuit-protection/maxi-inline-fuse-holder-8-gauge-translucent-red.html

-Henry

[salty9]

I was searching the web for arc quenching and found this: http://www.springerlink.com/content/g8j06g60228w7u8h/. PETN is hard to come by but I was wondering as a thought experiment what black powder could do. It made me think of Luke for some reason.

[shock]

What about a circuit breaker?

Seems like it would be better since it could be reset without tools or much fuss.

http://www.atensolar.com/m5/705-016--ou ... c-pnl.html