Alternative to class-T fuses?

Somewhere in the EU, I'm looking at class-T fuses and they are all >100$. Even at 60 it would be a tough sell for me.
I need to add a short-circuit protection to my 6kWh / 16S (58V) LFP bank, a maximum draw of 125A. Considering the use of a down-rated gG fuse since I rarely run my system at 100%. For example, from the Schrack catalogue, a 22x58 63A cylindrical fuse will trip after 1000s at 100A, which is not something that is likely to happen.

You are looking for the NH series fuses - they are square blade fuses made in the same general way that the class T is. Mersen makes a bunch of them as well as Eaton. Lucky you they are pretty inexpensive, unlucky you they require more space to mount them in. Siemens also makes them



the BS88 series is also a good choice.

brainwashed said:

I'm looking at class-T fuses and they are all >100$.

Click to expand...

BS 88 HRC fuses are equivalent in withstand rating and readily available. Example,
Farnell have outlets in most European countries.

Thanks for the suggestions. But are there any hidden downsides to downsizing the fuse? I'm expecting a faster trip at overcurrent situations and perhaps similar or lower power consumption.

the downside is you will get random trips from surges in current.

Best is to get a fuse sized to your expected use - i.,e. an expected 100amp current, 125amp sized wire, 150amp fuse - the fuse is only to protect the wire from shorts.

If you size things right nothing ever blows unless there is a short.

I mentioned in another post that there was a generic 32V/125A fuse installed in the inverter by the manufacturer. This blew, but it failed to protect the BMS. I'd rather have a fuse that can trip sooner and a few spares.

I bought Bussman T-class fusses from China for ~$40

I've seen a thread here where someone was linking to the same fuses on amazon for 10$ a piece. That's highly suspect since all the reputable sellers (mouser, farnell) charge a lot more.

If you are blowing fuses in the inverter you have another issue you need to solve.

Actual quality class T fuses are a bit spendy - a $10 would be very suspect and I would both cut one open to see if they left out the sand mixture and testing one or two at rated limits before I trusted them much... well, I wouldn't have bought that in the first place.

$35 is about the cheapest I have seen for a class T, and that was new/old stock in a holder from a defunct installer.

In Europe I would be going with NH series fuses by Mersen - I was actually looking if I could get some of that style here, but they are spendy. I got some Chints fuses of the same size certified by the German equivalent to the UL labs to test and see how well they are made.

The NH come in 4 sizes - NH00 NH01 NH02 NH03 ... sometimes the 0 in the middle is left off. They take a blade style fuse block and a handle to remove them from the holders, they are all but impossible to remove by hand safely.

brainwashed said:

hidden downsides to downsizing the fuse?

Click to expand...

That was an example , not the fuse you need . Consult the Farnel website. Example 125 amp fuse,

The best is the t-fuses of high amps and volt systeem.

Kelly Yan currently sells Bussmann and Littlefuse T-class fuses.

WhatsApp: 86-013510760041