| Electronics > Beginners |
| OScope Safety Question |
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| tautech:
--- Quote from: KungFuJosh on September 03, 2018, 09:16:40 pm --- --- Quote from: tautech on September 03, 2018, 09:01:34 pm ---Just confusion and seeing it from a different angle. A recent thread might offer some additional clarity: https://www.eevblog.com/forum/beginners/question-isolation-transformer-ground-floating-or-ground-shorted-to-neutral/ --- End quote --- I guess I'm a little confused by this: --- Quote ---The isolation transformer allows moving the ground point from the circuit breaker box to any point on the isolated side of the transformer --- End quote --- It's all still connected on the same ground. The only difference is the Neutral is separated from the ground. So what's the difference with connecting the ground? The thing that confuses me is that it reminds me of a well-known "genius" :palm: who actually suggested using a 3 to 2 grounding adapter on an IT to connect regular probes anywhere in the circuit like you would with appropriate differential probes. --- End quote --- I presume you mean on the isolated side, in which case there is no Neutral. There is only Live and Live WRT each other. Isolation transformers isolate the current/voltage supply from mains ground and thereby reduce the hazard of phase (live) to neutral and/or ground shock risk. Mains ground retained to the DUT is always preferable. |
| KungFuJosh:
--- Quote from: David Hess on September 03, 2018, 09:24:34 pm --- --- Quote ---The thing that confuses me is that it reminds me of a well-known "genius" :palm: who actually suggested using a 3 to 2 grounding adapter on an IT to connect regular probes anywhere in the circuit like you would with appropriate differential probes. --- End quote --- That does not make any sense unless you mean using a 3 to 2 grounding adapter on the oscilloscope. That does work for small or negative values of "work" and it even used to be recommended but it is definitely not safe for the oscilloscope or user. --- End quote --- Nope. The "genius" uses ungrounded DUTs on ITs. Exactly what I wrote. He literally has a video on youtube where he demonstrates doing that. :palm: :palm: :palm: Sorry if the quotes on "genius" didn't convey my sarcasm strongly enough. ;) |
| KungFuJosh:
--- Quote from: tautech on September 03, 2018, 09:30:29 pm ---I presume you mean on the isolated side, in which case there is no Neutral. There is only Live and Live WRT each other. Isolation transformers isolate the current/voltage supply from mains ground and thereby reduce the hazard of phase (live) to neutral and/or ground shock risk. Mains ground retained to the DUT is always preferable. --- End quote --- Correct, and I agree. I don't like the guy's stupid video spreading stupidity, but I'm not trying to start a social media war, it would just make me look bad. I get what you're saying, but when you wire a plug, or look at the IEC socket, it still says N on it. ;) |
| ogden:
When you connect scope ground clip to your device somewhere, you effectively ground that particular point of circuit to scope ground AND chassis of device. I do not find this safe, especially for your scope. Slightest error of yours or problem with equipment under test and least of your problems could be shopping for new scope. You definitely shall use probe that is safe w/o isolation transformer. |
| KungFuJosh:
--- Quote from: ogden on September 03, 2018, 10:43:45 pm ---When you connect scope ground clip to your device somewhere, you effectively ground that particular point of circuit to scope ground AND chassis of device. I do not find this safe, especially for your scope. Slightest error of yours or problem with equipment under test and least of your problems could be shopping for new scope. --- End quote --- I'm personally not an idiot (most of the time). I only connect the probe ground to the chassis ground. --- Quote ---You definitely shall use probe that is safe w/o isolation transformer. --- End quote --- I think something is lost in translation here. What do you mean? |
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