Maybe this a good place to note that UL and IEC standards for fuse rating are different. UL standards allow a fuse to open after 4 hours at rated load, whereas IEC requires a fuse to hold indefinitely at rated load.
To pass Safety agency review, for the equipment I designed professionally the manufacturer and their part number would be specified in the Agency report. Any alternative vendors would also be listed, and Agency testing would be conducted on all the fuses listed. It was a big deal that only fully tested fuse types were installed. And as you might guess, fuses were never made accessible to the user. If a fuse blew, the equipment had failed, so replacing a fuse would have pretty much been a waste of time anyway.
To pass Safety agency review, for the equipment I designed professionally the manufacturer and their part number would be specified in the Agency report. Any alternative vendors would also be listed, and Agency testing would be conducted on all the fuses listed. It was a big deal that only fully tested fuse types were installed. And as you might guess, fuses were never made accessible to the user. If a fuse blew, the equipment had failed, so replacing a fuse would have pretty much been a waste of time anyway.
It is developed in Europe as quite common with electrical items and it is a little more complicated than that with various classes. Quite extensive even as many different standards were combined:
https://en.m.wikipedia.org/wiki/IEC_60269
Not that it would make any difference in this case.
https://en.m.wikipedia.org/wiki/IEC_60269
Not that it would make any difference in this case.
Last edited:
The German Safety Agency, VDE, was one of the hardest to get approvals from! Absolute sticklers for detail!
I’m curious why there is no mention of time-current curves or I-squared t values when discussing the suitability of a certain fuse in a particular application.
When all the tiny magnetic elements of the core line up, the transformer is “saturated” and the primary is essentially just a wire with only its DC resistance limiting current flow. Of course, a properly designed transformer may come close to saturation at the peak of the AC line, but will never actually saturate. The problem with the initial application of power is that all the tiny magnetic elements could still be mostly lined up from when power was last present. Over time the elements will randomize, but if power is reapplied before this happens and the polarity of the voltage tries to drive the elements further in the same direction that they are already aligned to, you will experience core saturation at turn-on. It is completely random, luck of the draw, so to speak.
The time delay of the fuse must be chosen to account for a half cycle of saturation at turn-on.
The time delay of the fuse must be chosen to account for a half cycle of saturation at turn-on.
Th
Thanks for your constructive information. Previously I figured a fuse was a fuse was a fuse...
Maybe you could ask WHY the opinion is that Schurter fuses are supposedly less good than Littelfuse (correct spelling) fuses. It is like stating American cars are better than Japanese cars.
BTW the molten fuses in your Schurter PEMs are made by Bussmann (correct spelling) a series name/company by Eaton.
BTW the molten fuses in your Schurter PEMs are made by Bussmann (correct spelling) a series name/company by Eaton.
Last edited:
In my experience - and that is with 2.5 A fuses used in Pass derived amplifiers - the SCHURTERs would blow on first turn on or even more inconveniently once placed in position. I bought forty of them from MOUSER and most of them are gone.
Eventually I realized this had nothing to do with the circuit and would install a LITTELFUSE and all would be fine. Replace with SCHURTER and it would blow.
The LITTLEFUSE blow when they are needed to.
I suspect they are both made in China - I know the SCHURTER are. My assumption is LITTLEFUSE has found a better supplier. A more expensive supplier. The SCHURTERs were MUCH cheaper than the LITTELFUSE and that is why I bought them.
We all have to learn the hard way.
I would not have thought German chauvinism would extend to products made in China by a German company. I have no problem with patriotism.
I would certainly not be disappointed if I am the only person who has had trouble with SCHURTER fuses.
Who knows what an American car is these days? Are they Toyota, Honda, BMW, Mercedes, Ford, Chevy? They are all amorphous blobs of utilitarian conveyance these days. In fact I think BMW and Mercedes are making cars that are more "American" than the "Americans". Look at the avoirdupois of these beasts. Lead sleds is what we used to call "American" cars. The Germans are making modern Thunderbirds full of electronic gimmickry ready to fail at any moment. Luckily for most, they lease them and then it is on to the next ultimate driver in their ultimate telephone booth. No longer a "driving machine" but a place to carry on mindless conversation while hogging the left lane.
I miss German cars. I wish they were still made. How can one explain a five thousand pounds Porsche. Dr. Porsche would shake his head in shame and bewilderment.
Eventually I realized this had nothing to do with the circuit and would install a LITTELFUSE and all would be fine. Replace with SCHURTER and it would blow.
The LITTLEFUSE blow when they are needed to.
I suspect they are both made in China - I know the SCHURTER are. My assumption is LITTLEFUSE has found a better supplier. A more expensive supplier. The SCHURTERs were MUCH cheaper than the LITTELFUSE and that is why I bought them.
We all have to learn the hard way.
I would not have thought German chauvinism would extend to products made in China by a German company. I have no problem with patriotism.
I would certainly not be disappointed if I am the only person who has had trouble with SCHURTER fuses.
Who knows what an American car is these days? Are they Toyota, Honda, BMW, Mercedes, Ford, Chevy? They are all amorphous blobs of utilitarian conveyance these days. In fact I think BMW and Mercedes are making cars that are more "American" than the "Americans". Look at the avoirdupois of these beasts. Lead sleds is what we used to call "American" cars. The Germans are making modern Thunderbirds full of electronic gimmickry ready to fail at any moment. Luckily for most, they lease them and then it is on to the next ultimate driver in their ultimate telephone booth. No longer a "driving machine" but a place to carry on mindless conversation while hogging the left lane.
I miss German cars. I wish they were still made. How can one explain a five thousand pounds Porsche. Dr. Porsche would shake his head in shame and bewilderment.
Your AC Inlet is what I call a 3-in-1 because its on/off, fuse, and IEC terminals. I had one of these on my Krell clone and it was maddenning, it would blow fuses for no reason, and the switching was unreliable. I replaced it with another one, same problems. Finally I took it out and replaced with individual AC inlet, individual fuse holder and individual on/off switch. Has worked great for 10 years now. For this reason I have a distrust for those 3-in-1 inlets though I cannot explain why they were not reliable.
Probably it were F and T fuses mixed up. And even when being both 2.5A T it can have been a bad batch but it would require more details to determine why happened what happened.
Strange things do happen. Often they are solved. Also what is good today can be mediocre tomorrow.
Strange things do happen. Often they are solved. Also what is good today can be mediocre tomorrow.
Last edited:
I just bought a supply of littlefuse from Newark. Never thought about fuses, most I've had were BUSS.