Products > Test Equipment
Floating Scopes
Andy Chee:
--- Quote from: JDW on December 25, 2023, 01:53:41 am ---Lastly, the Rigol DHO800 documentation that came with my scope doesn't even use terms like "floating," and references to Earth Ground are few, which mean that people searching the documentation for important safety info might miss the topic altogether or think they are safe to use their new 12-bit scope in a floated condition.
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I did find this warning in the manual though!
JDW:
--- Quote from: Andy Chee on December 25, 2023, 02:21:54 am ---I did find this warning in the manual though!
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I consider that single mention inadequate. Furthermore, it makes no mention of other benefits, such as addressing common mode noise riding on measured waveforms. Dave's video about floating scopes even shows how the noise vanishes when the ground lead is connected (not on the DHO800/900, but another scope).
Not everyone reads the full documentation anyway. Therefore, putting a warning sticker on the AC power adapter itself and a second sticker on the ground wire that Rigol includes would be prudent. In the absence of that, I suspect many, MANY people will use it without the grounding wire. Which again is okay if you're testing under 30Vrms or under 42V peak, as Tektronix points out (which is all I test). Even so, proper grounding can address noise issues, as I've said.
Andy Chee:
--- Quote from: JDW on December 25, 2023, 02:29:07 am ---I consider that single mention inadequate.
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I'm sure someone with a bigger test instrument history than I could comment on this, but I might guess that every documentation from every manufacturer, printed in the last 25 years, has inadequate safety warnings!
Certainly older documentation could serve double purpose as a HOWTO instructional course in instrument usage and application. Modern documentation however implies a high level of assumed knowledge.
madires:
In case that power brick comes with an EMI supression cap between primary and secondary I wouldn't call the DSO floating.
JDW:
--- Quote from: madires on December 25, 2023, 03:34:22 pm ---In case that power brick comes with an EMI supression cap between primary and secondary I wouldn't call the DSO floating.
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That kind of statement seems to suggest this: "Go ahead and remove the ground from your scopes and then test high voltage because as long as you have an EMI suppression cap between the primary and secondary, it's not floating and therefore A-OK."
By using the term "floating" we are primarily talking about "safety from electric shock." And secondarily, we are talking about common mode noise reduction on measured waveforms too.
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