On Thu, Jun 6, 2013 at 3:12 AM, David Roberson <dlrober...@aol.com> wrote: > I am not exactly sure of where you are going with this discussion. When I > use the term RMS source voltage, I am referring to the RMS value of the > source itself at its fundamental frequency which is the only drive signal > present.
Dave, We're not talking of the same things it seems. Let's try to clear the confusion. > The input from the socket is a sine wave during the test and was looked at > visually by the same > guy, so it does not make sense to consider DC voltage present. How was it looked at, though? Oscilloscope inputs have an option to select between AC and DC coupling. If you use AC coupling, you will still see a nice sine wave but you will be blind to DC offsets. An oscilloscope wasn't used; a three-phased power meter was. We don't know if the voltage input of the three-phase meter is DC or AC. > DC voltage is not seen nor present at this point according to the > written information supplied by one of the testers. Yes, it's true that we got a comment later in the discussion saying that, but it's not written black on white in the report. Apparently it wasn't enough for Cude et al. since they kept talking about DC trickery, which is why I'm addressing the issue. Now there have been two proposed modes of trickery: (1) Diode trickery: Is it possible to fool the power meter by using non-linear loads such as diodes? (2) Mains trickery: Is it possible to fool the power meter by manipulating the tree-phased power? You are saying that (1) is difficult and I agree. I believe I've shown that (2) (using low-frequency signals) is possible only if the power meter is insensitive to DC voltages. It is still highly implausible for practical and sociological reasons. It would be great to know that the power meter IS sensitive to DC voltages as that would rule out (2) in a bullet-proof way. As for HF cheating (i.e. > 100 kHz)... it would take quite an RF genius to figure out a way of passing 3 kW unnoticed over a couple of random mains wires without starting a fire, damaging equipment nor giving RF burns to anyone. -- Berke Durak
