Quarktoo:

I never "took a swing" at you. I just wanted to discuss some of the statements that you made. Challenging some of your ideas is distinctly different from the kinds of comments you have been making about me and others. The whole point is to try to have a fun debate and not get ugly. Needless to say, your version of "reality" is much different from mine and that could potentially be an interesting debate on another thread.

Sorry if this is appears off-topic, but until we can get past how a transformer behaves in a "shorted" secondary condition, there's no point in examining the Barbat patent any further imho.

.99

I will comment on this and I think I was incorrect in my previous comments about this issue. I was focused on the fact that for an open or short-circuited secondary, there is no power transfer per se if you ignore the resistances of the two coils. That made me think that the "load goes away" when you short the secondary. I think that was wrong.

Obviously load on the secondary is being reflected back to the primary. Let's assume the source has an output impedance of 50 ohms and the transformer has a 1:1 ratio. Let's assume that the source is an ideal AC voltage source in series with a 50-ohm resistor. We know that beyond a certain excitation voltage you risk saturating the core (let's start off with a conventional power transformer, and let's ignore the losses in the core itself) so let's assume in this case you will not saturate the core.

So if you look at the secondary load starting at an open-circuit and then dropping going all the way to 50 ohms, the transformer should be operating normally, and the primary should see the same load. As you do this of course the power transfer to the load increases and the power losses due to the resistances in the wires of both the primary and secondary coils increase. Also, the power dissipation in the 50-ohm source itself increases during this phase also. The output voltage from the source will have dropped by half as the secondary load trends from open-circuit to 50 ohms.

Then when the secondary load goes from 50 ohms to zero ohms the trend lines change. The primary still has to see the impedance dropping, so the load on the secondary is still being reflected back to the primary. We know that less power is being transferred to the real load on the secondary because the impedance is starting to mismatch. We know that the output voltage from the source will continue to decrease, and end up at near-zero volts. By the same token the current through both the primary and secondary are increasing during this phase.

So in other words, a pure short on the secondary is seen as a pure short on the primary if we ignore the resistive losses in both coils.

When you finally get to a load of zero ohms on the secondary, the currents circulating in the primary and secondary coils are at a maximum. There is zero power transfer to the zero ohm load. At this point you have maximum resistive losses in both coils because the maximum current is flowing through both coils.

Again, since we are assuming that the source impedance is 50 ohms, then we know that the output voltage from the source on the primary coil is almost zero, it is effectively shorted out.

Finally, if your source impedance is very low, like from your AC mains, shorting out the secondary of your transformer will result in very high currents flowing in the primary and the secondary and the transformer will burn up.

For the air core case, everything is very similar with the exception that you can "saturate" that much sooner. There is a limited capacity for the volume of space between the two two coils to store energy. So you run into a "wall" if your excitation voltage and load resistance demand an energy transfer per cycle that is beyond the capacity of the air core and inherent resistance in the wires of both cores to sustain. This will result in the load on the secondary not being reflected back to the primary. The coupling will be too weak and the load on the primary side will appear to be at a much higher resistance than it really is on the secondary side. That could be developed further but I am done for now!

Anyway, thoughts and opinions welcome.

MileHigh