Voltlog
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- Опубликовано: 30 сен 2024
- In this video we’re going to do some tests on these ebay fuses to try and determine if they come close to the specified ratings of the original fuse.
Fluke 440mA Fuse DMM-B-44/100 Bussmann voltlog.com/y/m...
Digital Precision Pocket Scale 200g
voltlog.com/y/0...
Joe Smith RUclips Channel
/ @joesmith-je3tq
Blog post with high res img
www.voltlog.com...
Eaton Industries PRICE List 2 - 2017 : DMM-B-44-100 Dmm Fuse - Bussmann 10 units 22,10 €.
Well 3,5 € for ONE is OK. More expensive is a robbery ...
Most important is the internal resistance ≤ 0.7Ω (+ shunt resistor 1Ω = Burden Voltage error !!! ) and the melting graph 2.2A (10ms) 1.8A (100ms) 1.5A (1s)
Interesting job !!!
It would be interesting to open both a genuine fuse and a suspicious one and compare the quality of the construction under microscope. Looking the sand under microscope could also reveal a difference.
I will do that in a future video for sure!
It was kinda sad to see your fuses sacrificed for no conclusive result. :(
They seemed relatively close to specification on a number of aspects, but that 0.5A "tail" after blowing up is definitely suspicious, and needs to be investigated further, as you said.
It would be interesting to find a cheaper "brand", hopefully with a performance close to genuine Bussmann fuses, but with more reasonable prices. Thanks for doing this experiment.
The "tail" wasn't there for the glass fuses I tested. I will get confirmation in a future video if it's something related to the ebay fuses or not. Thank you for watching!
I bought 2 for 5.5 $ total. it's written made in Mexico on them. they came from Shen Zhen.
they are getting cheaper as more and more sellers have them listed.
This is what I love about channels like yours. I now have a real curiosity about fuses😀
As others have said my friend, you have started something here!
I would like to see you conclude this, fuses are expensive and a little bit of knowledge could go a long way.
Very interesting and appreciated✌️
thanks! I will follow up on the subject soon.
It acted like a polymeric positive temperature coefficient (PPTC) fuse, before it completely blew. !
Speaking of which, have you any videos on poly fuses?
No videos on poly fuses, it's not my specialty to test fuses. I did it because I would like to know if these fuses are genuine or not.
Joe tested these kind of fuses, his results were more conclusive, i.e. the braking time was like 1-2 ms, instead of microseconds.
Did you check the resistance of the fuse afterwards?
Joe tested the SIBA fuses right? I mentioned that in the video. Those have different specs when compared to bussmann fuses.
Despite of the inconclusive results was a very nice test, especially for the sustained current test. Nice work!.
thank you
Nice job!
Sorry for that you lost all of the fuses without getting good results for blow up time
sacrifices need to be made :-(
I get my fuses given. Was given this haul recently actually, all tested and working. If anyone wants to make me an offer, leave a comment here. postimg.org/image/tqms1z0b9/
nice
There is a fusing factor, which specifies how quickly they blow when over current, often it is 1.5X for 1 hour, 2.5X for 2 minutes or something similar, it might be on the data sheet. UPDATE, I just got to the bit where you show the graph... so yep, its there.
thanks!
For better testing results , the current limiting resistance should be much higher than the fuse resistance. For example, use Voltage 30 V and resistance 15 Ohm.
but that's not a current limiting resistance, it's there just to measure current.
Great video, thanks for testing the fuses
thanks!
Conclusion? Genuino o falso
not enough proof, need to do some more testing.
I think you should compare it to that old original because the manufacture is probably the same, just the label is different. What does the old one weight, and what's inside. The crimping of the end caps look different to the pic, and the stuff inside looks too white for beach sand.
To my eye the crimping looked identical, I will do a follow up video where I test a couple more and I will compare the construction with the old one.
I got some of them for my Flukes, they looked like the old ones but after testing them, both 400mA and 1A fuses I found out that some wont blow pretty much at any point, and the other ones blew after many times the rated current, completely fake I guess. The original Bussmann blew up instantly under the same test conditions.
During these tests it's important to pick a current value from their graph and see if the time it takes to break corresponds to the graph. Like in my case I went for 2A and it should have been 35ms but the fuse continued to pass 0.5A past that point so I need to do some more testing.
I looked at a DMM-44/100 (mexico) and a DMM-B-44/100 (not marked besides St. louis.
DMM-44/100 weighs 6.4322g. The DC resistance is 4W is 0.752. At 0.4491A, Vdrop at fuse is 0.36507.DMM-B-44/100 weighs 6.5466g. The DC resistance is 4W is 0.643. At 0.4491A, Vdrop at fuse is 0.30864.
This balance and HP meter are both in calibration.
Your DMM-B-44/100s are marked assembled in Mexico and your end caps are marked DMM-44/100. My B are not marked on the end cap but my non-B is and stamping appears the same font as yours. Weight looks good but strange the weight kept going down. Maybe you pre-sorted them. No matter, well in the ballpark. The DCR with a 2W again, I would say close enough. You ran a slightly lower voltage but the drop looks good. The picture in picture is a bit of a pain as I was trying to see if you had changed anything in the setup and of course it is all covered up. If the supplies negative output ties to neutral and I assume your scopes clip is also referenced to neutral you need to fix this. Put the shunt on the neg side of supply. Attach the scopes ground clip on the shunts neg side so everything is at the same reference. Not suggesting that is the cause of the recovery problem you are seeing but it is not the way I would wire it.
Thank you for the info! for the weight measurement the fuses are not sorted it's just a coincidence that they were in that order. My setup was as folows: positive from power supply, goes through relay, then through 1ohm resistor, scope is cliped here on the resistor, goes through fluke 87 on amps range, then through the fuse under test and back to power supply negative. The recovery issue was not there though when testing the 0.5A glass fuse with exactly the same setup. In my follow up video I intend to test another two of these ebay fuses alongside an original one and I will use the method you recommended with the shunt on the neg side, though in this case I don't understand how that is going to affect my measurement.
No problem. Glad to try and help. Many of us could benefit from the data you collect.
I was not suggesting that the way you have it connected is causing the recovery problem you are seeing. Only that normally I want my equipment at the same reference to avoid loops. Many supplies I have seen will use an RC to couple their negative output the their chassis ground. The probes clip on most scopes tie to chassis ground as well and I would assume these grounds tie together through their line cords. If your supply is made as I describe, now you have an RC in parallel with the fuse giving the path for the current to flow.
I would expect the HRC fuse to be different than the glass and it's hard to say how this would play into how it is setup.
I would assume you checked the supplies output to make sure it had good step response for the various loads before running the test. Mine was pretty poor which is why I have the supply running constant voltage followed by the current source.
It's simple enough to check everything to make sure things are working as expected before running the next set of tests.
Good luck with your testing.
Looking at your review of the supply you are using along with the high res pictures, there are three capacitors, C62, 63 & 66 that go between the outputs of the supply and the ground. The two are basically in parallel with your test fuse.
With the previous setup I did some tests with a load resistor and the response seemed fine, then I did some tests by blowing some cheap glass fuses and once again it looked okay. But just to remove any possibility of errors I will switch to using a linear regulator in cc mode in my next video, that should provide good regulation.
Understand that there is a basic difference between the glass and filled fuses. I wonder if the glass fuses continue to arc. All that ionized gas makes for a pretty good conductor and may fully discharge the capacitors in your supply. The filler in the HRC fuses are there to quench the arc. Maybe this basic property is why when a capacitor is placed in parallel with the fuses that one type returns to zero while the other does not. Hard to say but an interesting experiment.
Ebay is just a vast market for fake or substandard products. Anything safety related I would always buy from proper sources.
anyone would like to go the correct way but sometimes it's so expensive that you look for alternatives..
Could be genuine fuses at lower price only intended for sale in the chinese market, just like the chinese fluke meters.
that's exactly what I would like the story to be, because that way we all benefit from the lower price. However I do not like that 0.5A still flowing through the fuse for ~25mS possibly more and I need to do some more testing before I know what's going on.
Do you guys know the reason why HRC fuses cost so much? There is nothing special about it, it's just a piece of metal, ceramic, fine grained sand and tiny wire. You can buy two arduino UNO R3 board for the same price.
the safety tests they perform do increase the cost, but I don't think it should be that expensive. There is probably a good margin that the distributors also add and in general stuff that is meant for industrial use is more expensive, because what the heck they need it and it's just corporate expense.
very short acting (0.034 ms in data sheet). These fuses don't act like originals. And of course, the ability to interrupt very high current arcing. And repeatable results.
The burden voltage specified for example for Fluke 87 is 1.8mV/mA, that means an internal resistance of 1.8 ohms (meter shunt resistor + fuse resistance). The shunt resistor of my meter is 1 ohm, then I can say that ~ 0.7 to 0.8 ohms is the expected resistance for the fuse.
there will be a follow up video on the subject, I am just waiting for more of these fuses to be delivered.
Looking forward to it.
Isn't the remaining current caused by the coil of the relay?
it wasn't there when I tested some glass fuses..
Why didn't a 440mA fuse not blow at 1A? Whats the point of specifying such an odd rating, instead of 500mA, if it means nothing?!
not sure how they pick the rating of the fuse, but a fuse will blow because the wire gets hot and melts. In that test I was raising the current slowly so the fuse did not get hot immediately. Most of the time that's a good thing, because if you are measuring a 0.4A continuous current with occasional spikes at 1A that only last a few milliseconds you don't want your fuse to blow that fast.
The key part that makes a fuse work, is the filament. It must be made to high standards of known material and their conduction properties. That's what makes them expensive.
These Chines products all use fake stuff. The filament is probably regular copper wire with all it's 1% impurities.
I think that's why you measured different values when you measured the resistance of each.
I don't like fuses. I like the idea of a OP amp across a sense resistor, setup as a comparator (gate threshold is adjustable via a 10K-10 turn trim pot), to turn on a pair of P-MOSFETs connected back to back on the + side (high side), if the current through the sense resistors goes above the threshold, also it prevents back-flow from the load. Serves 2 purpose.
Take a look at this for inspiration. goo.gl/wfp7CQ
the solid state protection only works in low voltage circuits, when you start talking about high energy 1000V circuits and CAT ratings, I don't think it will "cut the mustard"
And that's why they don't use them in a Fluke meter. Covering their asses at the same time.
If you get test data from known originals, please post an update.
I for one, would be interested in your findings. Specially the tolerances.
Nice video.
I just noticed it's double "nn" in Bussmann.
thank you for pointing that out!
Great video !
thanks!