David L. Spencer wrote: > Jon, > Hopefully someone from RodL is listening and will give us the details > from the company history file, which went something like this... > The need to test the "Barrier" between line and digital signals evolved > as switching power supplies came into wide spread use. Before then, the > large mains transformer didn't "break down" the way these new isolation > xfmr's seemed to do (leakage). HP had a need to do it right and got > provided a fellow who worked there all the incentive he needed to start > a company which made Hi-Pot testers, Rod-L. I'm guessing the AC part > was an insitu thing...but the DC spec's came when high pot equipment > mfg's couldn't build cheap enough AC equipment that would handle the > leakage current... > I think I have most of this right, but it is hear say and from a > conversation I had with a sales guy about 6 years ago...hopefully > someone will fill in the cracks! > Jon Bertrand wrote: > > I'm a little off topic here: > > Does anyone know the "history" of hipot testing? > > Say someone tells you to "hipot" your cable or wire harness at > > 1000VAC, measure the current, and decide if it's low enough. Where > > did 1000VAC come from, and why is it AC? > > I'm guessing it all started in World War Two building B17's and such. > > Since AC was easy to make (you'd just use a transformer) people > > probably picked it for the supply voltage. I'd also guess that 0.1 to > > 5.0 mA was the common current range because it was the lowest amount > > your meter could measure (and it was just low enough not to kill you). > > Does this sound correct? > > Anybody know for sure?
This may well have been the beginning, but when I asked this to a lab I was shown some ANSI report detailing the 'expectancy' of 1Kv surges versus higher surges in the public power grid as the reason. Apparently 1Kv surges on the public power grid are quite common. I still don't know for sure. ******************************************************* Doug McKean [email protected] ------------------------------------------------------- The comments and opinions stated herein are mine alone, and do not reflect those of my employer. ------------------------------------------------------- *******************************************************
