phase converters for big iron

---snip--- confused by that. My understanding of RMS is that it is a way of expressing the energy under the curve of a sign wave such that the total energy was expressed as that of the peek of a square wave with equivalent energy. If that is the case then RMS and peek for a square wave would be the same but to convert between RMS and peek for a sign wave you multiple or divide by the square root of 2 or 1.414. I???m not trying to criticize Dwight at all here, I suspect he makes a good point, I???m just not sure I fully understood his post. Hi Mike I'll try to clarify. RMS means that if you feed it into a resistor, it will get as hot. Since a sine wave spends part of its time at lower voltages, it has to have a higher peak voltage to get the resistor as warm as an equivalent DC voltage. Now when we get to a square wave, we see that it has exactly the same voltage as DC for the same RMS level. It is just that it switches polarity, but that doesn't effect the power in the resistor. Now, when looking at what we call 115VAC, we are referring to its RMS level ( equivalent heating of a resistor ). A 115V square wave has a peak voltage of 115V as well as an RMS of 115V. This makes a difference when we use a load such as a rectifier. It only looks at peak. On the sine wave, that was about 160V while the square wave, it is still 115v. So, something like a light bulb will but as bright on the 115V square wave as 115VAC but a power supply with a rectifier will only see about the equivalent of 80VAC RMS sinewave source. This is outside of most switchers operating range. In other words, the square wave source would need to have an output of 160V to be used correctly with power supplies that have input rectifiers. I hope that makes more sense. Dwight