Hi, I have an existing PS using multiple chokes in the DC filtering for B+ supplies, that is fed from a valve rectified supply. The rating on one inductor in the circuit circuit is 60 mA and the circuit is at about 30mA steady state and the other is 150mA rated and has about 110mA steady state. So all good, and in the circuit they have been having no problems for about 20 yrs.....
So Why the question? Well I am changing some elements of the PS and some values of capacitors and the layout and on my new designs I see some large peak currents on start up modelled in PSUD2 with these new designs (and also actually the old designs)
So my question is should I just ignore these peak values as fake news (or irrelevant transient peaks that should not trouble the inductor) or should I pay closer attention to them?
The rectifiers are 5u4GB for the PS in question.
So Why the question? Well I am changing some elements of the PS and some values of capacitors and the layout and on my new designs I see some large peak currents on start up modelled in PSUD2 with these new designs (and also actually the old designs)
So my question is should I just ignore these peak values as fake news (or irrelevant transient peaks that should not trouble the inductor) or should I pay closer attention to them?
The rectifiers are 5u4GB for the PS in question.
what is the actual situation?, PSU2 software is fine, just like calculators, but it does not make you good in analysis as you like....
Thanks for the reply.
Here is an example of the existing system modelled for inductor choke inrush current and this has been working fine to date (20 years!) hence my question when I remodel as to the ability of a choke to take these sort of short term currents, assuming the software is fine and accurately predicting these large transient currents. By deductive logic yeah it's fine but, it sort of feels like it deserves a discussion with more experienced builders.
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What happens during turn-on doesn't directly relate to amp audio operation, but could be of interest if you were modifying or adding protection parts like a fuse. As evidenced by the 20 years, it is not damaging the choke, and the 5U4 has a 4A transient peak rating so again no issue.
Some discussion on PSUD simulation limitations in https://www.dalmura.com.au/static/Power supply issues for tube amps.pdf and in https://www.dalmura.com.au/static/Valve amp fusing.pdf
Ciao, Tim
Some discussion on PSUD simulation limitations in https://www.dalmura.com.au/static/Power supply issues for tube amps.pdf and in https://www.dalmura.com.au/static/Valve amp fusing.pdf
Ciao, Tim
There can be linear and nonlinear transformer/inductor inrush currents. If you are concerned about turning an inductor or transformer into a blown-fuse due to more or less linear expected inrush current, that might be one question. If you are concerned about nonlinear turn-on transients that can intermittently occur and which can sometimes damage some types of circuitry, that might be another question.
These articles are a fantastic learning resource - thank you.
I also had an email exchange with Pers from Lundahl and he confirmed that he was not concerned about the inrush into the chokes.
at power up, chokes are open circuit under transient conditions, opposite that of an uncharged capacitor....this is basic knowledge afaik....
We might say for some particular idealized series circuit model, when an idealized switch is closed at t=0, the instantaneous initial current in an un-fluxed ideal inductor would be i=0.
However, a physical inductor and power source may or may not be well represented by that model depending on the particular problem or question at hand. For example, there will be some rise-time when a physical device is first powered on. Also it might matter how long inductor current would stay reasonably close to zero. Even in an idealized model the 'open circuit' way of thinking about it is only exactly true for an infinitely short period of time. Physical inductors also have parasitic parallel capacitance, self-resonance, some practical breakdown voltage, possible residual core flux, etc. Such things may or may not matter, depending.
Indeed.
For any newbies though, seems like we should probably try to be clear about what is idealized theory and what is physical reality. We don't want newbies getting confused that the two are exactly the same thing, as sometimes seems to happen. Even experienced engineers sometimes seem to come to believe that the theory is what physical reality follows from. Not exactly so, I would say. Reality comes first, models are an approximation to that (sometimes an extremely good approximation, yet some other times not quite close enough for the problem at hand).
Just trying to keep people safe from developing wrong thinking as their electronics experience grows, is all.
For any newbies though, seems like we should probably try to be clear about what is idealized theory and what is physical reality. We don't want newbies getting confused that the two are exactly the same thing, as sometimes seems to happen. Even experienced engineers sometimes seem to come to believe that the theory is what physical reality follows from. Not exactly so, I would say. Reality comes first, models are an approximation to that (sometimes an extremely good approximation, yet some other times not quite close enough for the problem at hand).
Just trying to keep people safe from developing wrong thinking as their electronics experience grows, is all.
from where i came from, there are diy'ers who are highly acclaimed for building gears, they earn big bucks too, i can only admire and watch and whished i could =do the same.....
but ask him about chokes and stuff and he will give you a blank stare....
i compare them to musicians who can play good music from the music piece...
but ask him about chokes and stuff and he will give you a blank stare....
i compare them to musicians who can play good music from the music piece...
Thanks guys, I was after a view on the reality of a circuit that could have a short potentially damaging level of current if you believed the simulation. 🙂
ohm's law is very powerful!!!
knowing the dc resistance of your choke gives you ideas what could happen should the capacitor right after it shorted to ground...
knowing the dc resistance of your choke gives you ideas what could happen should the capacitor right after it shorted to ground...