Re: [CAD_CAM_EDM_DRO] Re: Power needed to drive 3 nema 42 motors?

Sorry Tom,
I ass*u*me*d that you meant to use that series-ed winding as output.
Yes, if you use it as an input, it should work... if it can carry the
input current, and... you have enough ampacity for the output winding
you choose. However, most multi-output transformers are also
multi-power, and seldom have the same wire sizes. Also, many times,
the low-voltage secondaries are just wound on the same layer, or
without layer insulation (because they assume you don't have to worry
about break-down voltage levels), and so, you'd lose some of the
advantage of isloation. Above all, avoid splitting a bi-filar winding
to add one half in series to the pri. Those wires lie right next to
each other!

RayHex

p.s. I designed transformers for a living for over 8 years.

----------

> From: caudlet <tom@...>
> > - - - - - - - - - - - -
> > You can even take a secondary winding and
> > > put it in series with a primary winding and use it to lower the
> high
> > > current secondary.
> >
> > ******* THIS THEN BECOMES AN AUTOFORMER! *******
>
> If you take any two windings on a transformer and wire them in series

> and induce an AC voltage across them then any OTHER winding on the
> transformer will output a ratio based on the total volt-turns of the
> primary. The suggestion was based on a transformer with multiple
> windings (>2). You do not loose isolation if the secondary winding
> is not physically connected to any of the primary windings.
> Transformers are designed as a group of windings each with a
> beginning and end (sometimes tapped at various points)placed on an
> insulated bobbin (conventional E-core transformers) and within the
> presence of a magnetic material. There are specific formulas that
> determine the amount of voltage that can be impressed on a given
> winding before the magnetic core of the transformer passes into
> saturation. This formula has the normal sustainable magnetic field
> below satutation in Gauss, along with the applied voltage, the number

> of turns, etc. What that means is that any windings in the field can

> be treated as part of the unit and used as long as you maintain the
> core below saturation. Note that current is not part of the turns
> ratio consideration and only comes into consideration when wire size
> is calculated. Wire size then determines how big your bobbin has to
> be to hold all the windings and that usually drives the size of the
> core. While there are other factors like air gaps, eddy currents,
> and such they only start to be significant at higher frequencies
> (KHZ).
>
> As long as you stay within the volt-turns constant you can put
> windings in series (boost or buck mode) and add or subtract
> voltages. Lets say you have a transformer with a 120V single primary

> winding and a 12, a 24 and a 36CT set of windings. If we apply 120AC

> across the primary we could get individual isolated (from each other
> AND the primary) voltages of 12,24 and 36 (or 18 at the CT). Now you

> can series any of the secondaries to get all kinds of voltages (36,
> 72,30,54,etc) The only limitation is that because of wire size you
> can only draw the amount of current of the lowest current winding.
>
> Conversely you can place 12VAC on the 12V winding and get 120V AC OUT

> of the primary (and so forth) Let's say you take the 24V winding and
> put it in series with the designated primary and impose 120VAC AC
> across the two end points. You have effectively increased the number

> of turns in the primary so the ratios to the other secondaries change

> by the same amount. I am not going to go through all of the math or
> examples. I will not go into out of phase (bucking) two windings but

> you get the idea. The more windings you have the more possible
> combinations you have. All of these presume you use a seperate
> isolated winding(s) as your final output.
>
>
> Addresses:
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