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| Floating Scopes |
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| Vtile:
--- Quote from: exe on June 27, 2017, 08:11:05 pm --- --- Quote from: Vtile on June 26, 2017, 09:31:12 pm ---PPS. The water circulating radiator under your workbench where you rest your feets seeking a warmth is also propably a directly grounded.. What a nice electrocution chair there. ;) --- End quote --- I got a shock every time I simultaneously touch the radiator and my laptop (that has metal enclosure). Why is it so? --- End quote --- I assume your laptop is powered by a charger. There is a few possible explanations, but I think I can assume (but it should be threated as high energy fault until it is solved ) that the shock you have had so far is rather low energy discharge as you are still wondering it. It is possible to get only a mild shock from full mains voltage, that is why it should be threated as a high energy fault. The real couse is of course almost impossible to quess without derailing this topic with more questions and answer. If you have reasonably trustworth DMM with atleast CAT II and similar level probes you can measure the voltage between the two objects. The probe placement is essential and needs to be on proper high impedance slots, typically the COM and V. In these kind of measurements DMM should start from the highest AC voltage range. You also should have a good workin position and not to touch both of the objects (except with the probe tips) while doing the measurent. What you have come across is indicating that something is wrong in your laptop or in your homes / workplace radiator. The problem is something that should be inspected by an qualified electrician by visiting on your place and measuring (the cheaper route might be to get the laptop inspected first at local electronics repair shop and if it is OK, then the radiator). For a starters you could start a new thread to ie. repair, general chat, or a beginners section. |
| tronde:
--- Quote from: serggio on June 27, 2017, 08:50:57 pm --- Your laptop have no ground connector at AC/DC power converter, but your laptop power converter can have capacitive coupling to AC (to phase) --- End quote --- It is quite normal to find a 1nF class Y1 capacitior connected from each of the mains supply phases to 0V output of the charger. This is becuase of noise reduction. You are normally allowed to have a ground leakage current of less that 0.25mA in Class-2 (double insulated [double rectangles] ) equipment. As you say, this can give a feeling of shock. |
| Red Squirrel:
TBH I sometimes float my scope, if testing something that I am unsure of that is ground referenced or any time I work with mains stuff. I actually feel safer floating it as I don't have to worry so much about where I'm placing the ground clip. I can put it anywhere I want, and sometimes you want that anyway as you want to test between two specific points, and they may not be ground. Of course the proper way would be to put the device you're testing on an isolation transformer, but that's not always an option if it's a large stationary object like a ground referenced battery bank or other hard wired stationary equipment. Idealy, what would be a good solution is a battery operated scope. Suppose one could run a scope off an inverter with battery pack for doing isolated tests. |
| tautech:
--- Quote from: Red Squirrel on June 27, 2017, 09:19:59 pm ---Idealy, what would be a good solution is a battery operated scope. Suppose one could run a scope off an inverter with battery pack for doing isolated tests. --- End quote --- The cheapest SAFE solution is differential measurement using 2 channels and maths or a differential probe. Period. |
| tronde:
Something battery powered with bluetooth could be useful. Does USB to bluetooth adapters exist? |
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