Please help me identify fuses by their ID and look

[slidincharlie (Carlo P)]

First question:
I have a few spare 1A fuses that I would like to identify: essentially I wonder if they are fast-blo or slo-blo and if they are good for tube amp applications.
I have two series of such spare fuses (both rated for 250V):
- one says BUSS MDL 1
- the other says 313 V 1A.

Second question:
what is the difference between the "thick wire" and the "thin wire with tiny sphere" inside a fuse? (see photo below)
P.S.: both unknown types above have the thick wire

[Enzo]

The thick wire is actually a little rod with very tiny wire wrapped around it, see? That is a slow blow fuse. You can usually google the part number or look it up in Mouser to get a link to a data sheet. For example Bussman MDL series fuses:

http://www.cooperbussmann.com/pdf/98...1b3dbca2f3.pdf

And Littelfuse:

http://www.littelfuse.com/data/en/Da.../313P_315P.pdf

Those are both slow blow fuses. The bead in the center of the one fuse adds some thermal mass to the weak spot in the center, adding to the time it takes to open.

[oc disorder]

The one with the bead in the centre appears to have a T on it.
This refers to Timed or Time lag which is another name for slo-blo fuses.
I sometimes wonder with some mass produced no name brand fuses , how accurate they are.
I suppose its just an extruded piece of wire with a known breakdown current.
As to whether they are any good or not I would suspect they are.
Well you can always try them !

[slidincharlie (Carlo P)]

Thank you guys!