Quick Question regarding the (600 mA range) Fuse of a Brymen BM869s - Page 1
Forum section: electronics / testgear

author: kblue
author_rank: Regular Contributor
timestamp: August 02, 2024, 07:50:52 pm
content: Greetings!Due to my own fault (forgot to change the probes into the amp-socket) i blow the fuse in the mA-range while measuring more than 1 amp. Ordered a new one but wasn't able to find the "original". The original is "red" and has the letter "B" in the name. While the other one is blue, has no "B" but appears to be the same. Are they? Or has the "B" variant something to do with the ability to measure 600 mA with a 440 mA Fuse?Thanks in advance!

author: Fungus
author_rank: Super Contributor
timestamp: August 02, 2024, 08:42:55 pm
content: Here's the datasheet.https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/data-sheets/bus-ele-ds-1047-dmm-b.pdfLook at the graph, it won't actually blow at 440mA. It needs over 1.25A to have any chance of blowing at all.This is the way with fuses. They all need much more than the rated current to blow them.(Think: It's supposed to be perfectly happy at 440mA under all conditions)

author: floobydust
author_rank: Super Contributor
timestamp: August 02, 2024, 08:46:38 pm
content: The Bussmann "B" question was raised back in a 2015 thread:https://www.eevblog.com/forum/testgear/difference-between-bussmann-fuses-dmm-b-44-100-x-dmm-44-100Seems to be (pun intended) RoHS or Fluke specific p/n but no difference.These fuses are counterfeited galore, shake them next to your ear to hear the sand inside, weigh them, measure their resistance etc.

author: Fungus
author_rank: Super Contributor
timestamp: August 02, 2024, 08:58:11 pm
content: Yes, beVERYcareful where you buy them. They're counterfeited to hell and back.If you're a hobbyist you could look in the official Fluke store in Amazon, they're reasonably priced there.

author: IanB
author_rank: Super Contributor
timestamp: August 02, 2024, 09:39:04 pm
content: Quote from: Fungus on August 02, 2024, 08:42:55 pmWell, it depends on both current and time. I blew the fuse in a fraction of a second when I inadvertently tried to measure the current through a 60 W incandescent bulb (500 mA). The switch on current was apparently far more than the fuse could sustain.

author: kblue
author_rank: Regular Contributor
timestamp: August 02, 2024, 11:32:39 pm
content: Thanks everyone and i hope the replacement is no fake. Its from a source i would consider trustworthy as a component reseller (Conrad) here in germany.

author: Fungus
author_rank: Super Contributor
timestamp: August 03, 2024, 04:20:09 am
content: Quote from: IanB on August 02, 2024, 09:39:04 pmThe first thing I tell my kids is: Never, ever, use the low current range, unless you have no other choiceandyou already tried the high current range first.High range can easily measure 500mA with enough accuracy.

author: Furna
author_rank: Frequent Contributor
timestamp: August 03, 2024, 11:15:23 am
content: Quote from: kblue on August 02, 2024, 11:32:39 pmConrad definitely trustworthy even if I belive you can find better distributors.I usuallu buy both fueses and a pouch with the multimeter; the pouch and the fuses live in the drawer while the multimeter lives around the tables.But at least I am not stuck whenI do mistakes ...Enjoy this fantastic multimeter! (that miss a decent duty cycle mesurment for AC)