In alt.home.repair, on Sun, 09 May 2021 10:52:09 -0400,
wrote:

On Sat, 08 May 2021 22:27:10 -0400, micky
wrote:



Douglas · May 17, 2018 says:
According to Littlefuse, the inventor of the ATO fuse, the idea that ATO
means OPEN and ATC means CLOSED is a myth. When Littlefuse applied for
patent rights for the fuse name, they could not patent AUTO, which they
wanted to do since the fuse is intended for vehicle use. So they
patented the name ATO for Auto.

Littlefuse's competitors obviously could not use the ATO name, so they
came up with ATC. Whether the myth of ATO=open and ATC=closed came from
those competitors is not clear. However, you will find that ATO is still
a trademark for Littlefuse, and ATC uses can be found with both closed
and open bottoms - which pretty much debunks the myth.


So what is an APR fuse?

https://www.optifuse.com/fuses-auto-blade-reg-apr.php but it doesn't
say! Not even it its glossary or selection guide.

https://media.digikey.com/pdf/Data%2...DFs/APR-UL.pdf
It seems to have something to do with how fast the fuse blows, but the
first link describes the whole category as Fast Acting/Blade Mounting.

I think the graph is bragging that they do blow quickly, not saying that
they are in any way slo-blo.

Or maybe they are saying they blow within a range of time, but then how
is that different from ATC or ATO?

ATC and ATO are just made by different manufacturers but follow the
same standards.

Yes, ATO was trademarked by Littelfuse, although now Littelfuse might be
moving to ATOF (tin plated) and ATO Ag (silver plated).

https://m.littelfuse.com/~/media/aut..._datasheet.pdf

Fuses are generally designated by a 3 character type. This is just the
tip of the iceberg but it will get you started.

WADR, I was already started. I asked what an APR fuse was.

There are dozens more types of fuses in just about any amperage you
want.


https://en.wikipedia.org/wiki/Fuse_(automotive)

Alas, that page just lists APR fuses along with ATO and ATC, and doesn't
say a word about what makes APR different from others.

"Regular (APR / ATC / ATO / ATS)"