RE: [TCML] My terry filter capacitors blew up!!

["Lau, Gary" <Gary.Lau@xxxxxx>]

Oops - I'm wrong!  The published schematic for a Terry filter uses only six 1.6kV-rated caps on each side, not 12 (I use doorknob caps on mine rather than an MMC).  So the total voltage rating would be only 19.2kV.  While that _may_ be adequate if nothing goes wrong, Terry filters are there for when things DO go wrong.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: Lau, Gary
> Sent: Wednesday, February 06, 2008 11:20 AM
> To: 'Tesla Coil Mailing List'
> Subject: RE: [TCML] My terry filter capacitors blew up!!
>
> I think the string Amir was talking about was the Terry filter cap, not his main tank
> cap.  The necessary voltage rating of these strings is only half that of tank cap and
> should be fine, unless his system goes into resonant meltdown.  It does seem hard
> to believe that one could smoke a 19.2kV-rated string in a Terry filter, as the total
> string would be rated at 38.4kV.  I wonder if there was a wiring error that caused an
> incorrect cap string configuration?
>
> Gary Lau
> MA, USA
>
>
>
> > You never want to run a MMC cap bank with a resonant match value for the
> > NST --- as you discovered, it will definitely blow up.  When resonance
> > between the power supply and cap bank occurs, the potentials can
> > definitely rise to high levels which can blow cap banks and even push
> > Terry filters to their limit.
> >
> > You should use approx 1.3 to 1.5 x resonant value for the capacitance.
> >
> > Also, you have way to few MMC caps in the series string.
> >
> > You need to run 2.5 x Erms value, ie, with your 15 kV xmfr, then 15 x 2.5
> > = 37.5 kV DC rating on the MMC for each series string.
> >
> > 37.5 kV DC / 1.6 kV = 23.4, ie, use 25 caps per series string.
> >
> > Dr. Resonance
> >
> >
> >
> >
> > > Hello all,
> > >
> > > Recently I built an MMC for my medium sized 4.5 inch diameter Tesla coil,
> > > and the total value for it is .0053uf at around 35,000 volts. This is
> > > resonant
> > > for my Magnetek 15kv 30ma NST.
> > >
> > > I had a Terry filter on the NST, (i bought the kit off ebay) and when  I
> > > ran
> > > the coil, the capacitors on the Terry filter blew up and caught fire. I
> > > was
> > > wondering why this is, and also I need to know how I can replace the
> > > caps.
> > >
> > > Do they need to be the exact same kind of capacitors? The  ones that blew
> > > were .0033uf at 1600v each. There were 12 capacitors in series.
> > >
> > > I was wondering if I could use these other caps I had which are  0.015uf
> > > each
> > > at 1600v. I have around 20 of those.
> > >
> > > Would the extra capacitance make a difference? How does the capacitance
> > > affect the Filter and in general the whole Tesla Coil?
> > >
> > > Sorry if I seem naive to this, but I'm only 14 years old.
> > >
> > > I really appreciate this a lot!!!!
> > >
> > > Thanks,
> > > Amir M.
> > >
> > >
> > >
> > > **************Biggest Grammy Award surprises of all time on AOL Music.
> > > (http://music.aol.com/grammys/pictures/never-won-a-
> > grammy?NCID=aolcmp003000000025
> > > 48)
> > > _______________________________________________
> > > Tesla mailing list
> > > Tesla@xxxxxxxxxxxxxx
> > > http://www.pupman.com/mailman/listinfo/tesla
> > >
> >
> >
> > Dr. Resonance
> >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla