| ID: | 4223 |
| From: | N <ni...@gmail.com> |
| Date: | Wed, 24 Jun 2020 23:06:53 +0200 |
| Subject: | Re: [pcb-rnd] Off topic (maybe) - Spice simulator - sparc model |
| in-reply-to: | 4220 from Evan Foss <ev...@gmail.com> |
DC might be worse, AC relays may not work for DC or have lower DC rating. Then welding DC is preferred, think sparc is extinguished at each zero crossing.
Arc flash is not good, this is what happen then welding, the UV light destroy you eyees.
Then thinking about it about distance then welding should be longer for thicker pins there higher current is used so I expect a longer distance could be kept ionized for higher current, might be important for creepage and clearance distances in high current circuits but never read anything about it. Then thinking about sparc is exactly what happen in welding and here https://en.wikipedia.org/wiki/Ionization_energy is some more about it but if you search for welding ionization there ought to be plenty to read about the sparc.
> It's also worth noting that because of the nature of plasma it's going
> to change DC vs AC. I saw a few hundred volt DC arc flash once. I
> don't recommend it.
>
> On Wed, Jun 24, 2020 at 4:31 PM Gabriel Paubert <paubert@iram.es> wrote:
> >
> > On Wed, Jun 24, 2020 at 01:01:19PM -0400, gene glick wrote:
> > > Can't you take a zener diode model and crank up the breakdown voltage?
> >
> > I don't think so, it has hysteresis, even worse than negative dynamic
> > resistance found in tunnel diodes. At least the model has to switch
> > between two states depending on past conditions.
> >
> > If you find a working diac model, it might be a reasonable starting
> > point:
> >
> > https://www.electronicdesign.com/power-management/article/21798585/model-diacs-and-triacs-for-acline-control
> >
> > as you can see, the model includes a flip flop.
> >
> > Gabriel
> >
> >
> > > Alternatively, make a voltage controlled switch that turns on at the needed
> > > voltage. I think a voltage dependent current source might also do the job.
> > >
> > > I'll bet there are many other ways to do this as well.
> > >
> > > On Wed, Jun 24, 2020, 12:22 PM Robin Laing <MeSat@telusplanet.net> wrote:
> > >
> > > > On 23/06/2020 08:20, Anthony Tuttle wrote:
> > > > > LTspice has a neon lamp model that can work without being too prone to
> > > > > convergence issues. I have also used R={expression} as the resistance
> > > > > value in resistors to simulate switches and this may be workable for an
> > > > > improvised discharge model.
> > > > >
> > > > > There are spice models for GDTs, you may have to contact the
> > > > > manufacturer directly to gain access. They are never perfect but there
> > > > > has been some work on advanced GDT models.
> > > > >
> > > > > On Tue, Jun 23, 2020 at 1:41 AM stefan <stefan.schippers@gmail.com
> > > > > <mailto:stefan.schippers@gmail.com>> wrote:
> > > > >
> > > > >
> > > > >> Hello,
> > > > >>
> > > > >> I am involved with a project that will involve high voltage pulse
> > > > >> circuit design and I am looking for a circuit simulator that will
> > > > >> give
> > > > >> us an accurate representation of a circuit.
> > > > >>
> > > > >> Needs to work with spark gap technology as that is the present
> > > > >> design.
> > > > >> Maybe gas discharge tube as well.
> > > > >>
> > > > >> Presently one member of the team is trying to use Multisim from NI
> > > > >> but I
> > > > >> am wondering if there may be a better package.
> > > > >>
> > > > > NGSPICE developers are doing a good job,
> > > > > ngspice netlists may contain capacitors, resistors, inductors with
> > > > > arbitrary expressions about their value.
> > > > > Moreover the 'B source' allows any type of voltage/current source
> > > > > with arbitrary expressions.
> > > > >
> > > > > Combining these elements a model for a gas discharge/breakdown can
> > > > > be created.
> > > > > The big issue is not the simulator itself, but the quality of the
> > > > model:
> > > > >
> > > > > 1) ability to accurately describe the device.
> > > > > 2) simulator must converge to a solution.
> > > > >
> > > > > Breakdown devices (devices with infinite resistance that start
> > > > > conducting with very low resistance when a voltage threshold is
> > > > > reached) are famous for giving convergence issues. This usually
> > > > > happen due to poor model description. A current limit must be
> > > > > included in the equations (no physical device can sustain 1e15 Amp
> > > > > of current :-) ).
> > > > >
> > > > > Stefan
> > > > >
> > > >
> > > > Thank you to all.
> > > >
> > > > The breakdown is where I ran into problems with a model years ago. It
> > > > was quicker to just setup an test bed and try it. Don't do enough
> > > > design work to take the time to learn the simulator. Same reason that
> > > > Multisim is being used.
> > > >
> > > > Robin
Reply subtree:
4223 Re: [pcb-rnd] Off topic (maybe) - Spice simulator - sparc model from N <ni...@gmail.com>