Thanks, with the component shortage, we just cant garantee that proper cheap DC fuses will remain in stock throughout our testing phase.....as such, for an LLC converter which is 2kW, 400vin, can we fuse it's 400v input with a dirt cheap 250VAC , 7A fuse, but put a cheap 10 milliOhm flame proof resistor in series with this (admittedly dodgy) fuse?
eg
12 milliOhm resistor......flame proof ness..
https://www.farnell.com/datasheets/2710520.pdf
Just doing a hobby prototype...multiple SMPS's.
Thanks, with the component shortage, we just cant garantee that proper cheap DC fuses will remain in stock throughout our testing phase.....as such, for an LLC converter which is 2kW, 400vin...
Thanks, with the component shortage, we just cant garantee that proper cheap DC fuses will remain in stock throughout our testing phase.....as such, for an LLC converter which is 2kW, 400vin, can we fuse it's 400v input with a dirt cheap 250VAC , 7A fuse, but put a cheap 10 milliOhm flame proof resistor in series with this (admittedly dodgy) fuse?
eg
12 milliOhm resistor......flame proof ness..
https://www.farnell.com/datasheets/2710520.pdf
If it's a hobby project, just stock up on them (fuses) while they're available.
What the hell, man… that makes no sense. Input and output fuses serve fundamentally different purposes.
You shouldn’t be going anywhere near mains (never mind 15kW anything) if you don’t understand this. And all this because you’re too cheap to spend 18¢ on an ordinary glass fuse?!?
Thanks, yes, but its strange theres no differentiation between a 1A fuse for say a 10MW.hr battery with 400VDC output, and a fuse for a 400Vdc ouput of an AC mains supplied Boost PFC......The Boost PFC requires a lesser fuse.
Thanks, yes, but its strange theres no differentiation between a 1A fuse for say a 10MW.hr battery with 400VDC output, and a fuse for a 400Vdc ouput of an AC mains supplied Boost PFC......The Boost PFC requires a lesser fuse.That's not true at all look up breaking capacity, which is the maximum current the fuse can safely interrupt, without posting a safety hazard.
Hey Treez.... Why haven't you asked about putting cheap AC fuses in SERIES for your DC hobby project??
Certainly that would increase the potential spark gap if they all should blow.
Thanks, yes, but its strange theres no differentiation between a 1A fuse for say a 10MW.hr battery with 400VDC output, and a fuse for a 400Vdc ouput of an AC mains supplied Boost PFC......The Boost PFC requires a lesser fuse.That's not true at all look up breaking capacity, which is the maximum current the fuse can safely interrupt, without posting a safety hazard.
A look in the datasheet of the model of the fuse is often necessary. The question as always is: which voltages (AC/DC and amount of) and prospective currents has the fuse to deal with?
Especially the curves and Integral values (necessary to determine timing of when the fuse begins to act) are needed to determine if a certain fuse is appropriate for handling a short at the position where it is deployed.
The form of the curve is mostly different, and for selecting to correct model of fuse you have to look at the situations and conditions when a short can occur- and determine, which parts of the system you want to protect.
I worked on a project last year involving two 2kV 800μF capacitors in parallel. Let’s just say that they could supply far, FAR, FAAAR more current than they were charged with. (Peak measured output current was 6kA. Not a typo.)
Hey Treez.... Why haven't you asked about putting cheap AC fuses in SERIES for your DC hobby project??
Certainly that would increase the potential spark gap if they all should blow.I know you said that in jest, but it would probably increase the breaking capacity and voltage. It would be a very good idea to both fuses must be replaced, even if only one of them blows, to avoid nuisance tripping.
For how long could they deliver this amount of current?
A ms or so
He has come to rely on the people here for answers he really should be able to derive himself; perhaps this blog has kept him employed.
QuoteFor how long could they deliver this amount of current?QuoteA ms or so
Thanks, this is the crux of it......in an ACDC offline PSU...if you fuse any DC rail in it...then once the caps on it have discharged...then that fuse is essentially in an AC circuit......as the short cct current will be going to zero every 10ms (8.33ms in US)......so you would think an AC fuse could be gotten away with.
QuoteFor how long could they deliver this amount of current?QuoteA ms or so
Thanks, this is the crux of it......in an ACDC offline PSU...if you fuse any DC rail in it...then once the caps on it have discharged...then that fuse is essentially in an AC circuit......as the short cct current will be going to zero every 10ms (8.33ms in US)......so you would think an AC fuse could be gotten away with.It’s been pointed out to you more than once that a 250V DC-rated 1A 20x5mm glass fuse can be had for pennies. So why is there even a discussion? Just buy the damned fuse and put it in.
Some people seem to like repeatedly asking a question and ignoring answers. Perhaps the answer isn't The Right Answer, perhaps they don't understand the answer, perhaps they think the answer will be different next time.
Hi,
Just doing a hobby prototype...multiple SMPS's.
We want to have a 1A fuse on a 60VDC rail.......why can't we use this.?..
MP001593
https://www.farnell.com/datasheets/3665667.pdf
....we know its an AC fuse, and could possibly release shrapnel if it blows.....since its not DC rated...but we will have protective eyeware on.
DC rated fuses are more expensive as you know.