inverter fuses ?'s

System · February 2007

My new samlex 600w inverter suggests 125A fast acting fuse on the dc side. (if i understand right, any surge, load or short over 1500w will blow it, right?).

specifically they recommend
http://www.amazon.com/BUSSMANN-4164-Limiter-Fuse-Block/dp/B000LDJM2S/sr=1-1/qid=1171388790/ref=sr_1_1/102-0741528-2344934?ie=UTF8&s=hi
and
http://www.amazon.com/gp/product/B000LEX2KA/ref=olp_product_details/102-0741528-2344934?ie=UTF8&seller=

I was hoping I could dedicate one of the breakers in my dc distribution panel but each breaker says 10kA. is that really 10000 Amps?
and , these breakers are also behind a 30a fused dc disconnect to the batterys too- so i guess that won't work. however, This dc disconnect has 2 fuse slots, one is empty and the one in use is this:
http://www.hardwareworld.com/Frn-R-30-Fusetron-Ctg-Fuse-p38H2IG.aspx
(between my batts and load center)
It would be nice if they made a fast acting 125A fuse of the same size/type so i could use this unused fused holder. (and maybe save $). do they?

if i have to get the bussman one, i suppose i need to mount it in a box (more $), recommend anything cheap?

thanks for any tips!

Brock · February 2007

Re: inverter fuses ?'s

I am assuming a 12v inverter? Weird, 125 amps would get you over 1200w, I suppose on surge.

If the main on your panels is 30 amps that won't work, even at 30 amps that is only 360w so it would need to be bigger.

Not very clean but you could just buy an inline 100 amp fuse, that would probably be the cheapest way to go.

System2 · February 2007

Re: inverter fuses ?'s

oh sorry, yeah 12v
yea i suspect its 1500w as the 600w inverter does have a surge capacity (i forget, 900w or something), so thats probably why its designed to take so much.

right i figured as much on the 30a fuse.

but to put a new one in the unused fuse holder looks like it would work, IF they have 125a FAST ACTING fuses of that size to fit the holder.
i'd run 6awg from the batts directly to this fuse (book recommends 4awg but i have 6 already..).

i see xantrex has something similar
http://store.altenergystore.com/FusesBreakersEtc/Fuse-Fuseblocks/Xantrex-Trace-110A-Fuse-Holder-WSet-Screw-Lug/p2119/
but still not the right fuse shape for me to take advantage of existing fuse holder.

BB. · February 2007

Re: inverter fuses ?'s

Just remember fuses (and standard breakers) open based on current and time... A standard breaker/fuse may never open at 80% current, open in a few minutes at 100%, or in a few tenths of a second at 125%... Really depends on design, and sometimes, external temperature... Also, fuses can fail from thermal cycling. Many devices (motors, electronics, lights) have quite high surges for a few cycles... Over time, these can cause fuse (and breakers) to fail with otherwise normal currents.

Regarding the 10,000 amp rating on breakers--It is possible that this is related to the way AC breakers (and boxes) are rated for the standard home (and probably office) input/distribution systems...

Basically, the pole transformer is rated to output no more than 10,000 amps--therefore any downstream distribution breaker on that line shall be able to interrupt 10,000 amps without failing (welding shut, causing external fires)...

But, remember, the standard breaker is rated for AC current--DC current (as discussed in other threads here) is much more difficult to break without arcing.

-Bill

DLwindsun · February 2007

Re: inverter fuses ?'s

Just so you dont void your warranty if something does happen make sure that you do use a 125amp fuse or breaker that is fast acting.

Something rated for 1500 watts is a bad idea because your actual battery voltage is going to be between 11.5-15 volts not exactly 12.

Most fuses like the bussman have an insulated cover but you better double check before you order.

System2 · February 2007

Re: inverter fuses ?'s

right thanks, i said 1500w only due to 12v x 125a = 1500, i realize thats variable as you say and that i will get the fuse based on a 125a rating not on a wattage rating.

so, nobody knows if theres a fast acting 125a fuse of that size ?

guess ill get one of the 2 i listed, probably the xantrex as it has the protective cover so i wont have to buy another housing _IF i can find a 125a class T fast acting fuse, they only seem to come in 110a or 200a. otoh the manual recommends the bussman.. sigh.

System2 · February 2007

Re: inverter fuses ?'s

One thing I saw inside a 12 volt inverter you might be interested in. It had an internal 100 amp fuse, made up of FIVE, 20 amp automotive fuses, all plugged into sockets that were soldered into the board and wired in parallel.
Hey, why not?
Wayne

System2 · February 2007

Re: inverter fuses ?'s

no kidding, im not going to try it but just curious: are those auto fuses fast acting? the samlex manual alludes to it having internal fuses as well,though i suppose i dont want to open it up, nice to know that when i finally get this thing in place it'll be double insured so to speak.

System2 · February 2007

Re: inverter fuses ?'s

They were standard automotive, plug in "ATC" type fuses, definitely NOT slow-blow, but I'm not sure if they would be considered "fast acting". Compared to Slow-Blow, they would be.
Wayne

niel · February 2007

Re: inverter fuses ?'s

the parallel arrangement will work, but if one fuse weakens and blows then all of them can pop with current matching or exceeding the remaining fuses. in other words at 80% load the fuses will pop because of the one fuse being no good. this is cheap to do, but it won't hurt the inverter unless they are made to pop slower.
i have issue with them putting the fuses internally like they do. many do not know that they are even in there and they aren't always made to be easilly replaced by joe blow customer as i've even seen some soldered in place. i like the old inch and a quarter glass automotive fuses, but to put up to 5 fuse mounts on the exterior of the inverter doesn't look good if they even have enough room to mount them and it shows how cheap they're being. actually the inch and 1/4 fuse mounts are more expensive mounts, but are still cheaper than the large single fuse and holder you'd need otherwise. those blade auto fuses should have a small indented, but externally accessible compartment that just has a cover on it to protect the fuses.

System2 · February 2007

Re: inverter fuses ?'s

thanks once again folks, i just ordered the bussman 125a fuse and holder from amazon . i found that lots of people including naw&s sell th class t fuses for inverters: fast acting and with the casing, but they only have 110 and i figured for a few extra dollars its nice to have te headroom of the full capacity of the inverter. im hoping ill NEVER need to replace it, but , maybe i should get a spare at some point. do these have any shelf life (ie: do they go bad after awhile? it'd probably not make sense to buy a spare now if so...

oh, and more important: this will be mounted close to batts of course, is ok to mount in a plastic box i pickup at hardware store, or should it be metal?
thanks!

crewzer · February 2007

Re: inverter fuses ?'s

I was hoping I could dedicate one of the breakers in my dc distribution panel but each breaker says 10kA. is that really 10000 Amps?

The "10 kA" value is the A.I.R spec, or "Amps Interrupt Rating", and not the service rating. The is typically the maximum current the breaker can interrupt and remain operable. And, as we've discussed before, do not mix a breaker's AC specs and DC specs.

HTH,
Jim / crewzer

mike95490 · February 2007

Re: inverter fuses ?'s

mattl wrote:

My new samlex 600w inverter suggests 125A fast acting fuse on the dc side. (if i understand right, any surge, load or short over 1500w will blow it, right?).

NO

Fuses have no idea about voltage, they are operate on AMPS. The only carry a voltage rating to prevent arc-over when they fuse (melt the element) What melts the element is IR losses, caused by AMPS. They are not rated in watts. Fuses come in different speed ratings, Fast, slow-blow, delayed..... The amount of overload, actually controls the speed of the blow, it may take 2 hours at 101% overload, but only 2 uS at 2000% overload

System2 · February 2007

Re: inverter fuses ?'s

The shelf life will be longer than all of us will live if kept away from water, corrosion, and the cat playing hockey with it.

Skip

System2 · February 2007

Re: inverter fuses ?'s

cool, thanks!

System2 · February 2007

Re: inverter fuses ?'s

hey guys, got my fuse and stuff in a few days ago, made up the cable ends in my spare time and today mounted the inverter and plugged it all it, works great!! did a test with my wifes electric mixer , works great.

anyhow since i plan to switch the long DC run to my office to be a leg of AC with this, Ill probably get myself a nice efficient, lead free ac power supply for my office pc that some of you know about. it runs fine but switching the dc plugs is a pain (walwart dc from the house on cloudy days, straight solar dc on sunny days)

Ill have the solar AC and the grid AC plugs next to each other and can switch plugs there there instead of the back of the PC directly, it will be easier..

it appears that the inverter uses about 20w when on w/no load, and it LOOKS like it uses a few watts even when switched off.
So I want to switch it. is one of those heayy duty click switches sufficient do you think ? Note that i will not be flipping the switch with loads on so it will only be a few amps. the issue im wondering about is when the connection is closed are those safe to have 120-125amps going through?
Maybe i wont have to bother but it so low light in the winter i really need to ensure every watt goes top the webserver

System2 · February 2007

Re: inverter fuses ?'s

hmm. bummer the dc rated click switch i was just looking at said 6a max so i must presume based on the size of connections that that must also mean how much can go through it.

has anybody bothered to put in a heavy duty switch for saving a few watts like this, or should i not even bother?

niel · February 2007

Re: inverter fuses ?'s

ever heard of a knife switch? yes, you have seen them on shows with mad scientists or when they go to execute a prisoner on death row. radio shack probably won't carry such a thing that i can remember. most aren't rated 125amps, but i think you'll be fine with one as i use one for a disconnect. try it and see how it works. if it gets hot then look for something like a blue seas battery switch.

System2 · February 2007

Re: inverter fuses ?'s

oh yea, in the frankenstein section

well, its weird my batts have been getting charged fairly regularly which is very different from the last 2 years this time of year. i will watch it nd see what we get. i know my batts are not 100% optimal from the initial abuse i put them through but they seem to do ok when i eq them a bunch in spring as i,ve been doing as i have the sun.

thanks!

crewzer · February 2007

Re: inverter fuses ?'s

bummer the dc rated click switch i was just looking at said 6a max so i must presume based on the size of connections that that must also mean how much can go through it.

Matt,

You may recall the fun li'l discussion we had here re AC Amps vs. DC Amps in switches (can't seem to find that discussion...). Contacts in switches and breaker tend to arc when a connection is made or broken. In AC applications, the arc tends to "self-extinguish" due to the change if direction of the current flow. Accordingly, the voltage and/current ratings for DC applications tend to be lower than those for AC applications.

Automotive and marine applications are often required to handle large amounts of DC current. In addition to the usual battery switches, Blue Sea makes a wide variety of low voltage / high current products. See: http://www.bluesea.com

HTH,
Jim / crewzer

System2 · February 2007

Re: inverter fuses ?'s

Thanks so much, that looks to be the ticket. i will see how it goes just shutting the inverter switch off, maybe the system can handle it. actually im sure it an handle a few more watts summers but by next winter ill look closely.

i just had to come back and report to everybody that im running the pellet stove on my solar!!!! WHOOOOO HOOOO
My batteries definitely wont be able to run this into the evening but its nice to be able to switch it on sunny days like today, and every little bit lowers my house usage. I'm thrilled

switching to ac sure does simplify wiring doesnt it>!? but i still so much is use the straight 12v for so its nice to have it without need for converters.

next on my list is going to be AC switching. as i described ill frequently be unplugging things (computer/stove) from solar AC to grid AC. is there any affordable way to do this so that the device doesnt have to get shutoff? It occurred to me while i was writing this that I could use my UPS. I have a couple of them around the house but I thought they used modsine wave? I recall one of the people here talking about old higher end UPS's that do output pure sine wave but I dont think mine do. the ups would be ideal as it would run the load briefly while i switch plugs.

anyhow, is there an affordable way to do this? if not switching plugs is still an improvement from having to crawl under the desk to pull out the little 12v power supply.

System2 · February 2007

Re: inverter fuses ?'s

crewzer wrote:

Automotive and marine applications are often required to handle large amounts of DC current. In addition to the usual battery switches, Blue Sea makes a wide variety of low voltage / high current products. See: http://www.bluesea.com

HTH,
Jim / crewzer

Jim, given my inverter will be using a MAX of 125A @12vdc this should definitely be ok right?
http://bluesea.com/category/4/14/products/6005

if so that's great as they are very reasonably priced around $20. i was expecting some huge expense. Im still surprised how much the dang fuse was.

crewzer · February 2007

Re: inverter fuses ?'s

Matt,

The UL-listed battery switches are great, and one will work fine with your inverter. I used a 9001E with my 600 W Exeltech for a couple of years with zero problems. See: http://store.solar-electric.com/basw1300amp.html

Have fun!
Jim / crewzer

Brock · February 2007

Re: inverter fuses ?'s

I have about half my loads going through my inverters. The neat thing about the larger inverters is you just pull their plug and they keep right on going. Very much like a huge UPS. I typically leave the inverters in “flt” or float mode so they just add what ever solar is extra to my loads on the inverters. Although with a stand alone inverter that won't work.

I like the idea of plugging all you computer stuff in to a UPS, then you could just move the UPS from grid to solar and nothing should happen. Any other switch on the 120vac side will likely mess up during the switch. I used to have a box with 2 Edison plugs on it and a DPDT (center off) switch and then a single Edison female plug. I could switch between two different sources, but of course I had to shut off the loads, if they mattered, things like lights were fine. But if you did this in front of the UPS it should be fine.

System2 · February 2007

Re: inverter fuses ?'s

yea the ups should work just great for the computer, i just had to replace one of em and got a slightly bigger one which will turn out to helpful. cool thanks! I guess switching the plugs isnt so bad. thanks!

System2 · February 2007

Re: inverter fuses ?'s

this gets better and better! i finished switching my wiring over from dc to ac for the home office: no problem at all running everything in my office through the ups, and switching plugs from solar to grid . my pc, cordless phone, speakers and monitor (as well as the ups itself) all switchable w/no power loss using the ups. the ups is a 800w model so i wont have to worry about bottleneck there. i dont have a battery meter anymore but i noticed the mx60 said floating at about 40w (also running the website, sometimes it can float as low as 25w running the website). anyhow, after turning everything on , it was at about 200w while booting up, and then settled at about 135w: so just under 100w running everything , also with the pc playing some mp3's. very cool, the whole office running under 100w

I should additionally run the stove w/no issue too

Gonna have to look for a small (<600w) AC for the summer.

i wonder if the pellet stove will run on a ups? since there's motors in in i hesitate to try. i rememeber trying my washing machine on the mod sine wave inverter and just plugging it in gave a horrible buzzing noise.. i yanked the plug quick and its been fine. is it safe to try it real quick on the pellet stove, or could it damage anything?

System2 · February 2007

Re: inverter fuses ?'s

Re pallet stove on MSW inverter, if there are electronics running off a transformerless low voltage supply, (that is a capacitor type power supply) the electronics could be cooked in perhaps less than a minute. The motor however, takes a while to heat up, so that's OK for a test. I don't like running "capacitor RUN" motors for very long on MSW though, because whither it hurts in the short time or not, there's a lot of nasty sounding buzzing, I'm always expecting the cap to overheat and blow it's guts all over the place, long before the motor gets hot. Otherwise, the only problems would be long term, that is the motor over heating if run for long periods of time.
Wayne

System2 · February 2007

Re: inverter fuses ?'s

thanks, yes, there are some electronics in it of course.. i will checkout my meter's manual to see if i can figure out how to determine if the UPS output is modified sine wave or not (uh.. i assume i can do that somehow). i am looking to get a better quality pellet stove next year finances allowing, and will look into some of the dc models. just fyi i found that one dealer says the "baby countryside" models are having alot of breakdowns, though the full, bigger countryside model has a good rep). some of the high end (or rather, aesthetic and expensive) ones like thelin even come with ups backup as an option.. hmm. sorry for this "every electrical question i ever had in one thread)" :-o

System2 · February 2007

Re: inverter fuses ?'s

mattl wrote:

sorry for this "every electrical question i ever had in one thread)" :-o

Well now, your questions and those of many others are the reason many of us check on the latest postings here. Sometimes we can help out, while at other times, we too wonder about the same questions.
And, thanks for your latest info on those stoves.
Cheers
Wayne

SolarJohn · February 2007

Re: inverter fuses ?'s

ever heard of a knife switch? yes, you have seen them on shows with mad scientists or when they go to execute a prisoner on death row. radio shack probably won't carry such a thing that i can remember.

I think Radio Shack stopped selling electronic parts, but I saw some at Lowe's, in the hardware department. They're in the drawers with specialty hardware items. They look like they're designed for science fair projects, not heavy-duty power systems. I would opt for a marine battery select switch instead.

John http://solarjohn.blogspot.com

System2 · February 2007

Re: inverter fuses ?'s

i am actually picking up one of those battery switches at a local place, not the bluesea but a very similar item from sunwize: 12/24vbattery switch for up to 350amps i think it was. has terminal poles like the bluesea which is good as I have a couple spare 2guage cables already with the ring connectors. thanks!

inverter fuses ?'s

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