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Products => Test Equipment => Topic started by: C_Norris on May 08, 2023, 07:46:58 pm

Title: Fluke 7261A Fuse selection
Post by: C_Norris on May 08, 2023, 07:46:58 pm
Hi,

I bought a Fluke 7261A on eBay from the US and had it shipped to the UK (which was still cheaper than buying one locally...).

I switched the voltage to 240V as described in the manual, and that worked (no smoke came out anyway), but it also says I should fit a different fuse.

Code: [Select]
4-15. The 7261A line power fuse is accessible on the rear
panel. Fuse requirements are a 3/8A MDL (slo-blo) for
line inputs of 100V or 120V and a 3/16A MDL (slo-blo)
for line inputs of 220V or 240V.

The fuse in it now says "3/8A 250V 3/3" so that seems valid for its original country, although I don't know what the "3/3" means.

Do they literally mean I need a fuse rated for 3/16 of an amp, i.e. 187.5mA?

And is there anything else special I should keep in mind when choosing a replacement?

Presumably it's only worked with this one because I didn't have it powered on long enough for the fuse to blow.

Any help would be appreciated, thank you.
Title: Re: Fluke 7261A Fuse selection
Post by: TimFox on May 08, 2023, 09:35:20 pm
With the power switch correctly set to 240 V instead of 120 V, the line current should be 1/2 of the draw at 120 V, so the 3/8 A fuse is too large.
Therefore, if the Fluke is working properly, it won't blow the 3/8 A fuse that came with it.
MDL is a standard slow-blow glass fuse in the American size of 1/4" diameter, 1.25" long, and 3/16 A is one of the available values.
Data sheet:  https://www.eaton.com/content/dam/eaton/products/electronic-components/resources/data-sheet/eaton-mdl-time-delay-glass-tube-fuses-data-sheet.pdf (https://www.eaton.com/content/dam/eaton/products/electronic-components/resources/data-sheet/eaton-mdl-time-delay-glass-tube-fuses-data-sheet.pdf)
Title: Re: Fluke 7261A Fuse selection
Post by: factory on May 09, 2023, 05:59:40 pm
Quote from: C_Norris on May 08, 2023, 07:46:58 pm
The fuse in it now says "3/8A 250V 3/3" so that seems valid for its original country, although I don't know what the "3/3" means.

Could the "3/3" actually be "313"? this is a Littelfuse type/series for 3AG slow blow glass cartridge fuses, in ¼" x 1¼" size.
https://www.littelfuse.com/media?resourcetype=datasheets&itemid=5c3f82d8-3d46-4d05-abe6-349ce263157b&filename=littelfuse-fuse-313-315-datasheet (https://www.littelfuse.com/media?resourcetype=datasheets&itemid=5c3f82d8-3d46-4d05-abe6-349ce263157b&filename=littelfuse-fuse-313-315-datasheet)

David
Title: Re: Fluke 7261A Fuse selection
Post by: C_Norris on May 09, 2023, 08:41:59 pm
Thanks both for your replies!

I think you're right David, it was 313 rather than 3/3.

I have ordered the Eaton BK/MDL-3/16-R.