Electronics > Projects, Designs, and Technical Stuff

Why are DMM fuse so expensive

(1/11) > >>

kuon:
I blew my DMM fuse, and when looking for a replacement, I found those:

https://www.digikey.ch/en/products/detail/littelfuse-inc/0FLU011-U/5233869

https://www.digikey.ch/en/products/detail/eaton-bussmann-electrical-division/DMM-B-11A/444040


I don't want to use cheap fuse and kill myself. But is there any safe cheaper one? And most importantly, I want to understand why they are so expensive.

Wolfram:
20 kA interrupt rating at 1000 V DC takes a lot more fancy technology than regular glass fuses. That combined with a moderately small industrial market and distributor markup makes them pretty expensive. Any fuse with interrupt current and voltage ratings matching or better than the original should be safe to use. Mass-market adoption of solar technology and EVs has grown this market, so there could be some cheaper options around.

Edit: The original has an interrupt rating of 20 kA at 1000 V AC/DC. The cheapest fuse on Digi-Key that meets these specifications is the 0ADHC9110-BE. It is listed in the datasheet for use with DMI (digital measurement instruments) and the press release for the series mentions multimeters, so along with the 30 kA interrupt rating I would personally be comfortable with using this one as a replacement. Note that this is qualified guessing on my part based on some experience with fuses, take safety advice from strangers on the internet on your own risk.

bdunham7:

--- Quote from: kuon on November 10, 2022, 04:09:24 pm ---I want to understand why they are so expensive.

--- End quote ---

36 francs?   :o  Because you're in Switzerland?  Here they're $21 in quantity 1 direct from Fluke and less expensive from other reliable sources.

kuon:

--- Quote from: bdunham7 on November 10, 2022, 04:53:43 pm ---
--- Quote from: kuon on November 10, 2022, 04:09:24 pm ---I want to understand why they are so expensive.

--- End quote ---

36 francs?   :o  Because you're in Switzerland?  Here they're $21 in quantity 1 direct from Fluke and less expensive from other reliable sources.

--- End quote ---

Well, I can find a bit lower price. But I am really curious what is inside to justify a price > 10$. Is it mostly "low volume niche market" factor?

alm:
They are expensive because they are designed to interrupt 20 kA in case someone connects the meter across a high-energy circuit so that someone can live to buy another meter instead of being severely burnt or even killed by an arc flash, hence the name high rupture current (HRC) fuses. They are filled with a sand-like substance that will quench any arc that might occur when the fuse breaks, and are encapsulated in a fiberglass-like material that should contain any blast that could occur within the rated parameters. I'm guessing the pricing is a combination of the more complicated construction, low volume, and the testing and certification the fuses will have to go through.

At one time Dave was selling fuses cheaper, though shipping from Australia may not make sense. And I think Fluke themselves also sells them cheaper than the original manufacturers. I wouldn't buy them from an untrusted source like eBay or Aliexpress: counterfeit HRC fuses are a thing.

Navigation

[0] Message Index

[#] Next page