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    Accuracy of differential probe?

    Hello,
    The Testec SI9002 differential probe says it is accurate to +/-2%. Does that mean +/- 28V? (I am referring to when on the 1:200 range)

    Testec differential probe (SI 9002)
    http://www.farnell.com/datasheets/10524.pdf
    ....SI9002 is on the 12th page..it says 2%, but does not say 2% of what?


    By the way, we are connecting the diff probe to the DPO2024 tektronix scope, and using that on the 100V/div range.....
    DPO2024 oscilloscope
    http://www.farnell.com/datasheets/1854407.pdf
    .....Accuracy is mentioned on page 8 but not for the 100v/div range.


    Its just that we've got a PFC output going up to 440V on constant load and wonder how accurate this is?...(the PFC output caps are only rated 450v, and we haven't got round to doing sudden full-load to no-load testing on it)
    We got the PFC made for us by outsiders.
    Last edited by treez; 5th August 2015 at 20:11.

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    Re: Accuracy of differential probe?

    The accuracy the probe refers to is almost certainly referring to +/- 2% of what you are measuring. If measuring 1V you can expect it to be within 20mV of the true value where as you are measuring 44V so you can only expect to be within 8.8V.

    I don't really know anything about PFCs so I can't be much help there but it does look like you're really pushing the max input voltage of that scope.


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    Re: Accuracy of differential probe?

    The specifications are for relative error of measured quantity unless specified otherwise. It should be noted that particularly oscillscope specifications are rather relaxed, actually achieved accuracy is often much better.

    I'm sure that you won't use the differential probe in the 100V/div oscilloscope input range, don't confuse the input sensitivity range with the displayed scale factor reflecting probe attenuation.


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    Re: Accuracy of differential probe?

    if you have 3% error in scope and 2% error in probe, then you have 5% total error before calibration with a test signal.
    A best design is easily achieved with good test specs™
    A better question deserves a better answer. ™
    ... so include all your acceptance criteria ( values, % tolerance) and assumptions in your question or any design.

    ... Tony Stewart EE since 1975
    - slightly north of Toronto


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    Re: Accuracy of differential probe?

    I'm sure that you won't use the differential probe in the 100V/div oscilloscope input range, don't confuse the input sensitivity range with the displayed scale factor reflecting probe attenuation.

    the DPO2024 has a 200:1 setting, so actually I can use the 100v/div range surely? ( I had the diff probe set to 200:1)



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    Re: Accuracy of differential probe?

    the DPO2024 has a 200:1 setting, so actually I can use the 100v/div range surely? ( I had the diff probe set to 200:1)
    Yes, my comment was about your statement
    .....Accuracy is mentioned on page 8 but not for the 100v/div range.
    The accuracy specification is referring to physical input attenuator settings, not nominal scaling. Do you unterstand the difference?


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    Re: Accuracy of differential probe?

    thanks, I see what you mean now.



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