Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Chris,
Yep, sorry about goofing up the first post. The MOT caps range in
values from .5 to about 2uF. I should have typed the .5uF value as an
example, but for some reason just had 0.1uF in my head. Anyway, the
idea of using them is just a means to an end since they are readily available.
Take care,
Bart
Tesla list wrote:
>Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>
>
>I just finished typing a response to your previous post, sent it,
>then when my inbox refreshed, I saw this post with your own correction.
>But in this post you mention .1uF MOT caps, and I've never seen any
>MOT caps with values this small. The caps I have are all slightly
under 1uF.
>
>Chris
>
>
>
>-----Original Message-----
>From: Tesla list [mailto:tesla@xxxxxxxxxx]
>Sent: Sun 4/8/2007 8:56 PM
>To: tesla@xxxxxxxxxx
>Subject: Re: Ballasting the secondary side of transformers
>
>Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
>
>Hi Chris,
>
>Hey, a correction to my previous post. I was looking at the primary
>side of capacitive ballasting. The secondary side is of course
>different. Your 4kV output at 240Vac input with 15 amp limit yields
>16000 ohms of reactance, so the limiting cap works out to 0.166uF.
>Certainly changes things. The C value is good but the voltage value
>would require strings. About 3 caps in series and 5 strings in
>parallel if using .1uF MOT caps rated at 2000V per cap. 15 total.
>Then, a 0.166uF value rated for the voltage should ballast to 15 amps
>ok on the hv side. Certainly possible using cheap multiple MOT caps.
>
>Take care,
>Bart
>
>
>
>Barton B. Anderson wrote:
>
> >Hi Chris,
> >
> >Good point! Capacitive ballasting the hv side could be practical for
> >some setups. Considering your 4kV output on the MOTs with say a
> >setup of 240 Vac input with a 15 amp limit, your looking at about 80
> >ohms of reactance which puts the cap at about 166uF. What value did
> >you use on your hv side and how did you connect it? (curious why the
> >7A draw open circuit).
> >
> >A pig limiting to 40 amps would use 6 ohms of reactance, so about
> >440uF. Of course, it's a fixed ballast, but that's not always a bad
> >thing (certainly can be done). Too bad, I once had about eighty
> >100uF 1.5KV caps lying around. Might have been able to
> >series-parallel for test. Only have one now. Sadly, I disposed of
> >them and I didn't have can crushers and coin shrinkers in my mind
> >those days (dimensions were around 4"x5"x9"). When you move from
> >Minnesota to California, the burden of heavy garage junk makes for
> >rash decisions.
> >
> >Take care,
> >Bart
> >
> >Tesla list wrote:
> >
> >>Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>
> >>
> >>Are a resistive ballast and an inductive ballast the only options?
> >>As I said in my last email, I'm trying out a capacitive ballast on
> >>the hv side, and it appears to be working. A capacitive ballast is
> >>much more feasible on the high voltage end because the capacitance
> >>doesn't have to be nearly as large. Also, I think there might be
> >>another plus for the hv ballasting, considering my setup in
> >>particular. Previously, I was using a MOT with the hv winding
> >>shorted as a lv ballast in series with two other MOTs with the
> >>primaries in parallel. Assuming that the MOTs have approximately
> >>the same inductance (particularly when the hv side is shorted), the
> >>ballast MOT will drop about 2/3 of the mains voltage, significantly
> >>decreasing the input voltage on the other transformers, and
> >>decreasing the output voltage. This is important in a system where
> >>a mere 4000 volts is the ideal output voltage. With a hv ballast,
> >>the impedance required to limit current to a sane amount should
> >>cause much less of a voltage drop. This appears to be the case with me.
> >>With a setup like this, there is however an additional disadvantage.
> >>With the hv end open circuit, it draws about 7A from the mains,
> >>whereas with the lv ballast, it only drew around 3A.
> >>Also, considering a hv inductive ballast, could an ignition coil be
> >>used? The insulation should be sufficient for the hv, and it
> >>should have a high inductance, but I'm not sure what the
> >>current-carrying capacity is.
> >>
> >>Chris
> >>
> >>
> >>
> >>-----Original Message-----
> >>From: Tesla list [mailto:tesla@xxxxxxxxxx]
> >>Sent: Sat 4/7/2007 1:53 AM
> >>To: tesla@xxxxxxxxxx
> >>Subject: Re: Ballasting the secondary side of transformers
> >>
> >>Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> >>
> >>Hi Bart,
> >>
> >>Ballasting on either side should be equally effective at limiting the
> >>current. Of course, on the HV side, the inductance value needs to be
> >>the turns_ratio (n) squared times larger because it has n times the
> >>voltage to deal with and needs to limit the current to 1/n times the
> >>current on the primary. This assumes an ideal transformer between
> >>the LV and HV ballast points.
> >>
> >>LV ballasting: + smaller inductance needed, lower voltage stresses.
> >> - larger current means larger guage.
> >> - core is needed to get the inductance and
> >>saturation needs to be considered.
> >>
> >>HV ballasting: + smaller current.
> >> - HV insulation needs to be considered.
> >> - inductance needs to be n^2 larger.
> >> - core is needed to get this larger
> >>inductance and saturation needs to be considered.
> >>
> >>These are all of the plusses and minuses that I could think of. If
> >>others, maybe someone else could chime in and comment on what is said.
> >>
> >>Gerry R.
> >>
> >>
> >> >Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
> >> >
> >> >Can someone please tell me why we are still ballasting on the LV
> >> >side of Pigs and PT's? This should be easy enough to do for a fixed
> >> >current limit. The costs associated with a LV ballast almost demands
> >> >we do this. The LV side is starting to appear very silly to me at
> >> >the moment. Granted, there are HV concerns, but is it really a big
> >> >deal? I get the feeling LV ballasting is simply convenient. However,
> >> >it is also expensive (unless one builds a ferrite ballast).
> >> >
> >> >Just curious is anyone else has contemplated a high side ballast.
> >> >
> >> >Take care,
> >> >Bart
> >> >
> >> >Tesla list wrote:
> >>
> >>
> >>
> >>
>
>
>
>