[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] Power Factor Correction
On Tue, Jul 15, 2008 at 5:58 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> Hi Phillip,
>
> 30uF for a 15/120 NST sounds low by at least a factor of 10. Was this
> determined using a Jacobs ladder for a load? I don't think that represents
> a correct load for determining PFC caps.
>
> Having the wrong PFC cap value cannot affect the current through the NST
> primary, or be responsible for the bubbling asphalt you cited. You're
> applying the same 120VAC to the primary winding, and the primary has no
> awareness of the presence of a PFC cap. Having too large a PFC cap CAN
> cause too much current being drawn from the wall socket, but the excess
> current would be going through the PFC cap, and it would be reactive
> current, so nothing gets hot except the wiring.
>
> Regards, Gary Lau
> MA, USA
The transformer is a 15/30 with shunts removed. I'm running the PFC caps in
series with the 277V line. Running smaller capacitances than 30uf yields a
lower current drawn on the 120V side of the variac. Running 40uF or above
results in a higher current being drawn from the 120V side of the variac.
In addition to this the short circuit current of the NST increases. Maybe
I'm wiring the caps incorrectly? I know for a fact that the amount of
current in the secondary increased to a very high level causing the asphalt
to be melted. I was running the jacobs ladder at the time and it became
notably louder. Several seconds later asphalt started bubbling up out of
the oil.
Schematic ... sort of.
120V ------------ Variac ------------ ~277V -------- PFC -------
|
NST
|
Neutral
-----------------------------------------------------------------------
>
>
>
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf Of Phillip Slawinski
> > Sent: Tuesday, July 15, 2008 4:59 PM
> > To: Tesla Coil Mailing List
> > Subject: Re: [TCML] Power Factor Correction
> >
> > As it turns out I only needed 30 uF of capacitance.
> >
> > On Tue, Jul 15, 2008 at 12:40 PM, Phillip Slawinski <
> pslawinski@xxxxxxxxx>
> > wrote:
> >
> > > How do I know what direction to go with capacitance? I'm running the
> NST
> > > with my Jacobs ladder to find the right value. So far I've only found
> the
> > > wrong value, and the very wrong value. Turns out if you get it wrong
> you
> > > actually increase [dramatically] the amount of current being dumped
> into the
> > > NST. I was running it and all the sudden the aspahlt I neglected to
> remove
> > > between the core and the HV windings bubbled up from the oil. When I
> run
> > > without the PFC caps I'm drawing about 15A, with the caps I was pulling
> peak
> > > currents of 35A! If I'm increasing current does that mean my
> capacitance is
> > > too high or too low?
> > >
> > >
> > > On Mon, Jul 14, 2008 at 11:58 PM, bartb <bartb@xxxxxxxxxxxxxxxx>
> wrote:
> > >
> > >> Javatc is giving a basic calculation for PFC based on the transformers
> > >> specs. This is only a ball park number. You must experiment to find
> the PFC
> > >> that works best for your coil. Does you coil have a variac control,
> external
> > >> current limiting, etc.. etc.. Experiment is the only way to find the
> "good"
> > >> value for your coil.
> > >>
> > >> Take care,
> > >> Bart
> > >>
> > >> Phillip Slawinski wrote:
> > >>
> > >>> I just scored 20 GE Dielektrol VI caps 10uF at 370V AC @ $0.10/piece.
> > >>> These
> > >>> should be good for PF caps. I'm wondering what size PFC cap I should
> use
> > >>> for a 15/120 NST. I've noticed that the value suggested in JavaTC
> for a
> > >>> 15/60 seems to be twice that of what others [notably Gary Lau] use.
> > >>> _______________________________________________
> > >>> Tesla mailing list
> > >>> Tesla@xxxxxxxxxxxxxx
> > >>> http://www.pupman.com/mailman/listinfo/tesla
> > >>>
> > >>>
> > >>>
> > >> _______________________________________________
> > >> Tesla mailing list
> > >> Tesla@xxxxxxxxxxxxxx
> > >> http://www.pupman.com/mailman/listinfo/tesla
> > >>
> > >
> > >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla