Re: [CAD_CAM_EDM_DRO] SERIES BUCKING was Re: Correct or Max voltage for Bridgeport Nema 42

Hi Lee,

Glad to hear it's working for you! And good use your existing hardware!

Alan KM6VV

studleylee wrote:

>
> Hi Alan,
> I've come around to your thinking on the series-bucking connection
> to simplify the setup. The regulators work, but its not
> a simple setup. I found a good 2KVA autotransformer with a 240/208
> or 120/104 ratio that is perfect. Later I played with the contol
> transformers that I removed and have found that by seperating the
> mirrored cores and removing the outer control winding( common around
> both cores), there's plenty of room to add 20-30 turns of heavy
> secondary windings. This makes possible
> to get 2 usable autotransformers from one of these SeriesII control
> transformers. This may be a good trick for people with these seriesII
> supplies laying around. The power transformers are overbuilt and
> heavy wound, so Just run them at 110vac (vs 220) and make take
> 2 of the control transformers and wire them as mentioned.
>
> Picture of the control transformers:
> http://www.users.qwest.net/~indigo_red/files/xfer/bptransCtrl.jpg
>
> -Lee
>
> --- In CAD_CAM_EDM_DRO@y..., "studleylee" <indigo_red@q...> wrote:
> > Hi Matt,
> > I've got the origianl SeriesII triple set of transformers, of which
> I
> > removed the control transformers. This leaves the 3 supplies main
> > tranformers,bridges,caps. I'm running those at 110 volts (vs th e
> > original 220) which gives about 88vdc each. Then I went nuts and
> > made 3 regulators which can span about 20V at 10amps and can be
> > adjusted, to create the final 75vdc. The regulators have current
> and
> > device SOA protection that trips a master supply relay when
> exceeded.
> >
> > Alan Marconett KM6VV proposed a neat simpler alternative:
> > >Hi Lee,
> > >Yes, 88V is a little high. What you can do is find a 12V (or as
> > >desired) filament transformer with a secondary current the same or
> > >greater then the PRIMARY current needed by your transformer.
> Connect
> > >it in SERIES BUCKING, and you can drop the resultant secondary
> > voltage >as required. This sounds similar to what your "control
> > transformers" > might have been doing! But simpler, smaller!
> > >Kinda like a "fixed" VARIAC!
> > HTH