tan delta

Discussion in 'General Electronics Chat' started by AMIT_GOHEL, Aug 6, 2011.

  1. AMIT_GOHEL

    Thread Starter Member

    Jul 13, 2010
    67
    7
    hello friends , working on tan delta measurement(dissipation factor) and want to measure up to 0.0005 accuracy,,, so my 1st task is to measure phase differance between two voltage signal, highly accurate(up to 0.01 degree),so please give me the guidance on base of circuits, and any link or website which can help me..
     
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  2. DickCappels

    Moderator

    Aug 21, 2008
    2,651
    632
    The kind of accuracy that you are shooting for is generally pretty difficult to obtain. If you can test with a low enough frequency signal, than you can merely use two precision zero crossing detectors to compare voltage and current, but you will have to assure that you amplifiers prior to the zero crossing detectors do not add too much phase shift.

    Here is another approach, though somewhat more complicated, it has less dependence on phase shift in the analog processing because the phase difference is made digitally in the time domain:

    http://cappels.org/dproj/1kzhlmeter/1_KHz_Inductance_Meter.html
     
    Last edited: Aug 6, 2011
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  3. smaik

    New Member

    Jun 25, 2011
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    hello, i am working on this project with amit, thank you very much for your precious reply ,I would like to know you that i am working on on the suply 230 v, and 50HZ , 50 hz is enough low frequency or i have to work on less than 50 hz..?
     
  4. DickCappels

    Moderator

    Aug 21, 2008
    2,651
    632
    At 50 Hz, you should not have much trouble making accurate phase measurements.
     
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  5. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    And I assume you are going to correct for harmonic distortion of the sine wave. I think at the accuracy you are looking for this may be an important source of error.
     
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  6. smaik

    New Member

    Jun 25, 2011
    2
    0
    to russ_hensel: yes I get lots of distortion at small measurement. for that purpose i connect one capacitor of 33nF which reduse lots of noise


    Kindly find the attachment herewith of my work progress, it is not so lengthy . here i am measuring phase differance between two current. one current across standard capacitors and another. resistor capacitors circuit.

    i will be big thank full if you give me other technique which make me closer two my aim..
     
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