Mystery Fuse - how to tell if limited markings?

[canidoit]

I bought these fuses a while back and was replacing a fuse in my equipment and noticed it only had the following markings.
250V 2.5A

There is the SA and UL markings but their more for Quality/Safety stamps from what I have read.

Is there a way of identifying whether it is Slow or Fast Blow or any other specifications, just by looking at it?

Thank you.

 

[radardoug]

Its just a regular fuse.

 

[soapfoot]

Is there a “T” before or after the current rating by any chance? Like “T2.5A” for example

If so, it’s a slow-blow fuse, as T stands for “time delay”

 

[MagnetoSound]

Yeah, that’s just a regular old quick-blow fuse.

You can generally tell slo-blo fuses visually, they have either a coiled spring attached to the filament, or a coiled filament, or sometimes a flat filament that’s thinner in the middle.

(Assuming, of course, a glass case.)

 

[rock soderstrom]

Is there a “T” before or after the current rating by any chance? Like “T2.5A” for example

If so, it’s a slow-blow fuse, as T stands for “time delay”

I don't think it's particularly important, but I believe originally these terms come from the German language area, then the abbreviations are also correct again

F= Flink, M=Mittelträge, T= Träge and so on, see chart

 

[canidoit]

@rock soderstrom yes that is the-same info I was looking at.
@soapfoot It has nothing except 250V and 2.5A markings. Hmm, strange as I have all these other fuses and they have the other markings.

@MagnetoSound and @radiodoug, so a regular fuse means they are all Fast Blow. So any fuse without any other markings, means it is Fast Blow? Does it depend on country you are from, or its an International standard?

Thanks.

 

[trobbins]

It's all down to standards. The UL and SA markings indicate the fuse complies with UL 248-14, which has an unfortunate side effect that it shouldn't be used in equipment with continuous current of greater than 1.9A (75% of 2.5A). If it was the more common IEC compliant fuse used in Australia then it could be used at up to 2.5A.