Iain Buchanan wrote: > um, I just came across a problem - it won't work with an AC power cord, > because you have active and neutral both going through the clamp in > opposite directions, hence they'll cancel each other out. You need only > the active going through the clamp...
Or only the neutral. It doesn't matter, actually. > But "how it works" (with AC) is something like this: AC produces a > field around the wire as it "flows". This field in turn will induce a > current in a wire placed close to it. Loop a wire (transducer) around > another wire (AC current flow), and you can inference the change in > current in the original wire by measuring the current flow in the loop. > > It doesn't work with DC, as DC doesn't create a field (at least, not > when it's steady. When switching on and off a DC device, you'll still > get a change in current) > > IANAE(lectrician), so this might be complete bunkum, but that's how I > remember it anyway. You almost got it. Actually, it's not necessary that the current be AC: even a DC current produces a magnetic field around the conductor (albeit a DC field). The clamp is a ferromagnetic ring that "concentrates" the magnetic field, and it is interrupted at one location by a hall-effect sensor that measures the magnetic field. The current can be calculated from the magnetic field intensity and the diameter of the clamp ring. -- Remy Remove underscore and suffix in reply address for a timely response. -- gentoo-user@gentoo.org mailing list
