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Re: first post (fwd)
---------- Forwarded message ----------
Date: Wed, 15 Aug 2007 17:04:04 -0400
From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: first post (fwd)
If you want to play things safe, the rule of thumb is 2.5*transformer peak
voltage (not RMS voltage) for the DC voltage rating of your MMC, but as
Scott said, you could get away with less, a design program would help, or a
lot of math (I can't help you with that!). Some people like the GE42L
series capacitors, .33uf at 2000V. Some people do not trust these, as they
are film type, not film foil (the attachment is not as good inside). I have
never used either types (I use a Maxwell), So I cannot personally attest the
the toughness of either one. Read this, it explanes why people prefer the
CDs.
http://www.tb3.com/tesla/capacitors/GE_Capacitor_Issues.html
Good luck.
Scott Bogard.
>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: first post (fwd)
>Date: Wed, 15 Aug 2007 13:28:34 -0600 (MDT)
>
>
>---------- Forwarded message ----------
>Date: Wed, 15 Aug 2007 19:00:49 -0000 (GMT)
>From: huil888@xxxxxxxxxxxx
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: first post (fwd)
>
>Garry -
>
>Why did you select the .015uF C-D type 942 capacitor instead of the .15uF?
>
>Your target capacitance value is .06uF, and let's say (just for example)
>you want a DC voltage rating of 16KV. (If you don's use the resonant
>capacitors on the tertiary windings of the transformers you probably won't
>get the full 4,500 volt output.)
>
>A string of eight capacitors will provide 16KV (DC) voltage rating at
>.01875uF. Three such strings paralleled will provide .056uF, very close to
>your target value. The .15uF capacitor has a peak current rating of 432
>amps, and an RMS current rating of 13.5 amps. Your three paralleled
>strings would have a peak current rating of about 1300 amps. A total of 24
>capacitors would be required, and even at $3.00 each that's less than $75
>total. (Bear in mind you may decide to incorporate a larger voltage
>margin, which would require more capacitors.)
>
>If not already done, you should complete all the design work using one of
>the TC design applications that will calculate peak tank current so you
>can make sure that the MMC array will handle the current, and make sure
>that your RSG and safety gaps are set to keep peak voltage in the primary
>circuit within the limits of the MMC. How much voltage "safety margin" you
>want for the MMC is something you will have to decide for yourself, but
>you might want to get the transformers hooked up first and verify what
>the actual peak output voltage is to help you decide on MMC voltage
>margins.
>
>Regards,
>Scott Hanson
>
> > ---------- Forwarded message ----------
> > Date: Wed, 15 Aug 2007 12:07:09 -0500
> > From: Terri Neeley <neeley_111@xxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Subject: Re: first post (fwd)
> >
> >
> > Exactly what Mr. Lux said. Many people have used these transformers
>with
> > success and I thought it could be a cheaper alternative than stacking
> > nst's. The transformers I have are 4500v 450ma btw. So if you use Jim
> > Lux's config you essentially split the current between the two and
>double
> > the voltage. I will be using a synchronous rotary gap. My question is
> > are there really any alternatives to CD942's? What about wima fkp1's?
> > They seem to be much cheaper considering the cd's are over 3 bucks a
> > piece and I would need 6 strings of 18 of the .015mF for this coil. I'm
> > just very new to this and I really just want a cap or mmc that will be
>as
> > reliable as reasonably expected to be. Any really good alternatives
> > besides the CD's? There gonna set me back at least 350$ for them.
> >
> > Garry Neeley
> >
> > > From: "Tesla list" <tesla@xxxxxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Subject: Re: first post (fwd)
> > Date: Wed, 15 Aug 2007 10:23:54 -0600 (MDT)
> > >
> > >---------- Forwarded message ----------
> > >Date: Wed, 15 Aug 2007 09:16:18 -0700
> > >From: Jim Lux <jimlux@xxxxxxxxxxxxx>
> > >To: Tesla list <tesla@xxxxxxxxxx>, tesla@xxxxxxxxxx
> > >Subject: Re: first post (fwd)
> > >
> > >At 08:38 AM 8/15/2007, Tesla list wrote:
> > >
> > > >---------- Forwarded message ----------
> > > >Date: Wed, 15 Aug 2007 08:29:08 -0700
> > > >From: huil888 <huil888@xxxxxxxxxxxx>
> > > >To: Tesla list <tesla@xxxxxxxxxx>
> > > >Subject: Re: first post (fwd)
> > > >
> > > >Terri -
> > > >
> > > >First question is about your HV power supply transformers.
> > These are
> > > >nominally rated at 4500 volts RMS, 400ma. I assume that
> > you intend to
> > > >connect them in series to obtain 9KV RMS AC output?
> > Peak-to-peak voltage
> > > >will be about 12.7KV. Are you sure that the transformer
> > insulation will
> > > >withstand this? One good flashover at this much current
> > may destroy the
> > > >transformers.
> > > >
> > > >How will you limit secondary the current to 225ma?
> > >
> > >I think that the plan is to cascade the two transformers in
> > series,
> > >using the 600V tertiary winding, so the "high" transformer's
> > core is
> > >floated at 4500V.
> > >
> > >These things have a fair amount of leakage inductance, so
> > the output
> > >current is limited.
> > >
> > >
> > >
> > >I built a similar cascade, using 4 transformers: two
> > cascades, with a
> > >center ground, and it's in many respects like a giant NST.
> > >
> > >
> > >
> > >
> >
> >
> > > More photos, more messages, more storage—get 2GB with Windows Live
> > Hotmail.
> >
> >
> >
>
>
>
>
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