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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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18th Jan 2019, 5:20 pm | #1 |
Nonode
Join Date: Jul 2010
Location: Folkestone, Kent, UK.
Posts: 2,172
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Fuse rating
I was given a batch of 1.1/4" fuses, they are voltage rated on the end caps as 125V or 250V, but the current rating is odd.
The 250V reads 'S MDL 8/10' and the 125V 'SS MDX 6.1/4'. What are they anti-surge, slow blow? Many thanks |
18th Jan 2019, 5:48 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Fuse rating
Those are Bussmann time-delay fuses - have a look at:
http://www.cooperindustries.com/cont...nicfuses3.html and http://www.cooperindustries.com/cont..._MDL_MDL-V.pdf |
18th Jan 2019, 5:57 pm | #3 |
Nonode
Join Date: Jul 2010
Location: Folkestone, Kent, UK.
Posts: 2,172
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Re: Fuse rating
Many thanks G6, that's them
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18th Jan 2019, 6:47 pm | #4 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: Fuse rating
If you have not guessed already, they are 800mA (8/10A) and 6.25 Amp (6 1/4A) That is the Americans for you ;-)
They are called 'dual element' fuses, I think the idea is for the solder to melt on prolonged over current. Then the spring pulls the two halves apart. Alan |
21st Jan 2019, 2:29 pm | #5 |
Nonode
Join Date: Jul 2010
Location: Folkestone, Kent, UK.
Posts: 2,172
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Re: Fuse rating
Thanks for the info Alan. I did wonder if the 6 1/4 was 6.25A but not the 8/10A, not having dealt in fractions for many a long year!
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26th Jan 2019, 12:22 pm | #6 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 901
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Re: Fuse rating
Just a note that as those fuses are from USA and are UL rated, they aren't designed to operate continuously above 80% of rating. In contrast, IEC rated fuses are designed to operate continuously at up to 100% rating.
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26th Jan 2019, 1:20 pm | #7 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,345
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Re: Fuse rating
Interesting: I hadn't realised that rating fuses by blowing current was a UL standard. I had thought that rating fuses by blowing current rather than carrying current was peculiar to automotive fuses.
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26th Jan 2019, 2:07 pm | #8 |
Nonode
Join Date: Jul 2010
Location: Folkestone, Kent, UK.
Posts: 2,172
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Re: Fuse rating
Many thanks trobbins. I had to look up 'UL rated' and didn't realise there was such a diverse range of types!
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26th Jan 2019, 2:10 pm | #9 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 901
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Re: Fuse rating
UL 284-14 is the north american standard, and is noticeably different to the IEC 60127-2 standard. For most, a fuse is really the final last gasp of protection before fire and brimstone, but for many applications a fuse may be able to be 'designed' to provide much more selectivity as to what fails and when. There is an info doc in the sticky on Fuses that goes in to some detail on that.
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