Re: MOT Caps DC Limit

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: tesla@xxxxxxxxxxxxxxx 

Thank you Chris.

That site was useful and confirms my guess re ability of MOT caps to 
be used as
DC filter caps OK.

Unclear about your ref to needing to be bridge rectified.

I will be running a full wave bridge from the MOTs (lots of 1N5403's I recall)
so they will be hit with 100Hz ripple. Itt is essentiasl to run full wavew or
the DC rthru the MOT would be a real problem. I suspect that the loss angle at
50Hz you refer to is not a problem and the ability of lots of MOT's to charge
these caps is also not a problem. I'm really checking to see if these caps can
take about 4kV DC each for a short period.(site ref noted 4.3 x rated AC for
10sec)

Yes the 50Hy is a lot. I do need to reconfirm the design calcs from Ritchie
Burnetts  site. I'm fixed with the 90nF tank cap, desire for 8kW thru-put and
the 16kv DC so this drives the rest of the component values) My first DC
resonant charge coil uses 2 MOT secondaries (each 19hy) in series and the MOTS
held up OK. This is the same design as Steve Connor et al are using with a
single MOT and opposing multilpiler systems to get plus and minus 5 
kv which is
extended to 20kv total in the charging inductance when the field collapses.

An isolated MOT (ie floating secondary only used) seems to be able to handle
the voltage without oil (so far). In my case that is only 5kv per MOT between
the secondary terminals.

I am extrapolating that if 2 MOT's secondaries in series as inductors on a
smaller coil can take the back EMF of a fully charged inductor field collapse
then 3 in series (well isolated from each other and gnd) should be OK in a
bigger coil.

I'm most impressed and the smooth current draw and easy control of power these
designs offer and want to convert my 6MOT stack AC SRSG design to a 
DC resonant
charge system.

Rgds
Ted in NZ


> Having just tried a few experiments with a 50ma 10KV NST, it turns out
> that
> MMOCs don't work unless they are bridge rectified. The losses must be
> too
> great for any significant charge to be built up in the first place. The
>
>