On Thu, May 30, 2013 at 1:38 PM, Joshua Cude <joshua.c...@gmail.com> wrote:
> I don't buy it. The reactor is a sealed faraday cage, so it's not going to > care about ripple or dc vs ac. It's just a thermal interface. The reactor might require or might be incompatible with low-frequency AC magnetic fields, which can go through 3 mm of steel, especially AISI 310 steel which has very low magnetic permeability. (Faraday cages bounce off electromagnetic signals (balanced E + B) but not necessarily penetrating magnetic signals.) In addition we are told the instantaneous power was about 930 W. If unfiltered, full-wave rectified AC was used then in 10 ms, that 930 W will supply or fail to supply about 10 J. As this is metal here and not water the thermal masses are pretty low: for the steel casing which has a thermal mass of about .15 J/K this would mean a change of 1.5 degree, 100 times per second. With a diffusivity of .36 m2/s this 100 Hz thermal signal would certainly reach the core. Who knows if the core minds a 100 Hz thermal+magnetic purr? > But in any case, in the dummy run, they measured the power to the ecat so that > suggests it's an ordinary ac signal. Anyway, a box powered by ordinary mains > can produce any signal shape they want. They wouldn't go to 3-phase just to > skimp on diodes and capacitors. The 3-phase looks more like obfuscation to me. Again, if they need to have precise PWM without a large 100 Hz ripple, they will have to produce high-power DC, and they will want it to be reliable. It's not just a matter of "skimping" on capacitors. The lifetime of aluminum electrolytic is very sensitive to heat. If you run them hot (~ 80C) they will last less than a year... and that's if you're lucky. And given the amperages, they will run hot. Also we are talking of controlling devices having a multi-kilowatt output, and putting these devices together to produce megawatt outputs. This means that there will be lots of heat. It makes sense to think that Rossi wants a modular e-Cat with a built-in controller. So the controller has to withstand high temperatures. And we know what happens when the power is uncontrolled. If he uses electrolytics, and those fail, they may wreak havoc into the control loop and the reactor might overheat and melt. If you don't want that kind of thing in a kettle, you certainly don't want it in a cold fusion (or whatever this is) device. In other words, this device needs a very robust controller that can withstand high temperatures, and needs to have a multi-year lifetime. Electrolytic capacitors seem unsuitable. As a side node, the use of tri-phase power seems to indicates that this is the real deal. Why would indeed Rossi bother with that if he didn't have a true need to industrialize his product? -- Berke Durak
