I am sure you have seen automotive 'Blade' fuses. They are special fuses constructed to protect equipment that is DC powered. I have asked around and determined that a 125v DC rated fuse is more than acceptable to protect 240vac equipment without arcing due to the zero-voltage presence in AC power.
Blade Fuse with "Horseshoe" Element Visible
I am in need of a fuse handling similar current but in a package that is slightly smaller. I will not go into details, but all other fuse package types will not suit my application, only the blade fuse or something extremely similar. My plan is to remove the casing, cut the leads down, and re-place the filament in my own packaging, made of the same material. Blade fuses also give the advantage of not requiring an inert gas inside, making them an even more attractive choice for this application. Eventually, I will approach a blade fuse manufacturer and have them make my custom fuse. Same element, same material, different outer package, but too high cost for a prototype ;).
My question today concerns not AC or DC, but the physical nature of these fuses' construction. There is virtually no information on the internet about the stresses on the element within the fuse. Is the plastic case there just for safety reasons or does it also exert a positive or negative compression force on the element, to encourage it to fuse right in the middle?
For those who do not have experience with the manufacturing of these fuses, perhaps you could share in the comments some advice on how to measure if the element is in compression without bending it in the process?
There seems to be some confusion as to what I am trying to design here. I am making a smart fuse (regular fuse + extras). I will leave you to guess what those 'Extras' are for NDA purposes. The 'regular fuse' that will server as the core of this design requires bulk order from china and they offer no English support. This post simply served as a general 'are blade fuses more than just a piece of (precisely machined) metal with a plastic cover' inquiry. This will save me from placing a custom order for some of the most expensive blade fuses out there just for an experiment that will be more involved than I originally bargained for. Blade fuses are not my only option, but if the metal part inside the case is not in tension to blow right in the middle, than they are the best option out there because they:
Blows in a predictable physical location (vs Cartridge type that can blow anywhere along the filament)
Are not surrounded by an inert gas, making prototyping custom fuses easier
Have an easily removable filament
Have the potential to be cut down to a smaller size so that their longest dimension is smaller than any other fuse out there for their current rating.
After the bit of feedback I have gotten, I think I will grab a cheap bag of these off ebay or stop by my local garage and get testing. I will post any interesting developments.