RE: [TCML] Taming the Beast: Inductive Ballast vs. Variac, PFC

[Jeremy Scott <supertux1@xxxxxxxxx>]

I'm not sure what I'm going to make yet,  but an ASRG
is an option. I have one of those massive DC treadmill
motors plus the speed 
control for it. Could swing a 12" Garolite disc easily
:)


--- "Lau, Gary" <Gary.Lau@xxxxxx> wrote:

> Before going too much further, consider this.
> 
> If using a .03uF cap with a 120BPS SRSG and a 14.4kV
> xfmr, your theoretical maximum power throughput is:
> 120BPS * .5*C*V^2 = 120 * .5 * .03E-6 *
> (14,400*1.414)^2 = 746 Watts
> You can use the biggest baddest pig available, but
> that cap and gap can't pull any more power than
> above.  This is why pig-powered coils typically use
> async RSG's - to permit higher break rates and pull
> more power.
> 
> Regards, Gary Lau
> MA, USA
> 
> 
> 
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx
> [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf Of David Rieben
> > Sent: Tuesday, May 27, 2008 8:55 AM
> > To: Tesla Coil Mailing List
> > Subject: Re: [TCML] Taming the Beast: Inductive
> Ballast vs. Variac, PFC
> >
> > Hi Jeremy,
> >
> >
> > ----- Original Message -----
> > From: "Jeremy Scott" <supertux1@xxxxxxxxx>
> >
> > > That sounds interesting, and I may just take you
> up on
> > > it. I have another option as well that I'd like
> to
> > > explore too.
> > >
> > > I've got 225 amp lincoln arc welder (240VAC@50A
> input)
> > > which I was going to use but I have some safety
> > > concerns. 1) What kind of current limiting will
> it
> > > provide at 120V as opposed to 240V and 2) Does
> this
> > > work if the welding leads are shorted vs. not?
> (The
> > > switching mechanism temporarily breaks the
> secondary
> > > welding circuit and I am worried that this will
> > > translated to 'full blast' if I am running the
> coil
> > > in between clicks.)
> >
> >
> > I would assume that Ohm's law would apply and that
> > the arc welder would limit the current at 120
> volts 4X
> > what it does at 240 volts. Shorting the welding
> leads
> > allows for the maximum current throughput since
> that's
> > effectively what you are doing when you weld with
> it.
> > Switching the tap selector switch will only
> disconnect
> > the power in between clicks, not run at full
> blast. How-
> > ever, you will find a label that states to NOT
> switch
> > the selector while it's under a load, as this
> would quick-
> > ly errode the switch contacts.
> >
> >
> > > I may settle for it being adjustable only when
> the
> > > main power is off, but I really like the idea of
> > > ramping up slowly by pulling a core.
> >
> >  This type of welder does not utilize the sliding
> core to
> > adjust the current. There are simply multiple
> taps.
> >
> >
> > > Okay now that's interesting. I originally wanted
> a
> > > small 5kV pole pig. But I settled for a PT as an
> > > intermediate stepping stone from the NST.
> > >
> > > I take it these things are much more robust than
> the
> > > typical NST? (Fried my first one, like everyone
> else
> > > :) ) Are RC protection circuits on the secondary
> a
> > > good thing to have for it?
> >
> >
> > Yes, PTs along with pigs are much more robust than
> > fragile NSTs and do not require RC circuit
> protection
> > although you can still use circuit protection, if
> desired.
> > I believe the HV side of all 14.4 kV pigs and PTs
> are
> > rated at 110 kV BIL, so they typically have no
> problems
> > standing up to the nasty kickbacks of a Tesla tank
> circuit.
> >
> >
> > > I will probably not run that high a kVA on my
> coils,
> > > as I haven't sized the other components for it.
> (The
> > > spark gap I'm planning on using is a 120bps 1/4"
> > > electrode SRSG 'propeller' style with tungsten
> rods
> > > and the secondary is a 25"x6.5" form. Caps are
> going
> > > to be MMC or a series of one, two or three
> Maxwell
> > > .03uf units.)
> >
> > >From your description of your proposed SRSG
> design,
> > I'd say that your coil should easily handle 4.2
> kVA. Just
> > make sure that you run enough strings of your MMCs
> (if
> > you choose the MMC route) to handle the RMS
> currents.
> > I woud opt for a (4) sereised-parallel
> configuration of those
> > .03 uf, 35 kV Maxwells (for a total of .03 uFd at
> 70 kV)
> > as these have been known to fail from overvoltage
> with 15
> > kV NSTs. This will also spread the RMS currents
> over the
> > 4 of them to share the load.
> >
> > What size toriod terminal do you plan to employ? A
> good rule
> > of thumb is to make it about the same demensions
> of the
> > secondary coil, which in your case would be 25" x
> 6.5".
> >
> >
> > > I have to play with javatc a bit more to figure
> out
> > > the specs exactly, and to start that I need to
> know
> > > what I can put into it.
> > >
> > >
> > > Do you have any issues balancing them? For
> example,
> > > can one core be left in while the other is out
> or do
> > > you have to move them in parallel?
> >
> > >From what others have stated, balancing is not
> that big of
> > an issue in this situation.
> >
> >
> > David Rieben
> 
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> 



      
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