Had a typo -- reposting with typo fixed.
---In TekScopes@..., <louis.wilen@...> wrote :
I'm trying to verify that my Isolation Transformer (IT) is really going to provide "tech" isolation. The goal is to use the IT between the mains and the DUT. (I will definitely NOT be using the IT to float the scope. No need to even go down that path of discussion at all.)
I looked through the previous discussions on this topic and found this comment from Tom Miller, which pretty much sums up the main goal of using an IT:
"The goal is to separate ground from neutral for the unit under test. Do not isolate the test equipment. Think of it as making a transformer isolated power supply by adding the missing transformer. Now, you can connect the scope ground clip to either side of the AC line in to the TV (or whatever)."
So I obtained a Tripp-Lite IS-250 and disconnected the internal neutral-to-earth ground on the output side of the transformer (as explained in ) ) so that I'd have a "tech" Isolation Transformer.
The earth ground is still connected to the IT chassis and IT third prong on the input and output.
But considering the entire electrical path, I'm still not convinced that I have full isolation. As we all know, the neutral is connected to earth ground where the power enters a house (typically in the circuit breaker box). Therefore, I'm thinking that there is still a current path between the IT output neutral and earth ground. Hence, when plugging a grounded "three wire" DUT into the IT, shouldn't I use a 2-wire to 3-wire cheater plug between the IT and the DUT to achieve full isolation?
(I submitted this question to the guy who produced the YouTube video (Todd), but I don't have 100% confidence in his answer. I have a lot more confidence in the answers that are provided on this forum.)
Thanks for any replies.
Louis
W3VVV
