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Re: MMC dissipation factor measurement
Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>
Check out the precision LCR meters from QuadTech (formerly General Radio)..
They've got a downloadable applications note on measurement techniques and
precisions.. (0.1 ppm for the fancy series 7000 at about $10K...
Essentially, these beasts work with a precision A/D measuring the voltage
and current (actually voltage across a resistor), and then a bunch of
calculation and averaging... (0.0005% accuracy on D) Interestingly, it can
measure D more accurately than C or Z (0.05%)
Agilent (nee HP) also has some apnotes on measuring LCR circuits, with some
detail on measuring D of a C...
(they have a box, the 4284A...)
Tesla list wrote:
> Original poster: "Malcolm Watts by way of Terry Fritz
> Hi Terry,
> On 16 May 2002, at 21:13, Tesla list wrote:
> > Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> > Hi All,
> > The question comes to me tonight....
> > I have a TEK 3012 scope. I have a TEK 5100 voltage probe, lots of Pearson
> > current monitor CTs... I have a lot of sine wave generators with low
> > impedance... Like 350kHZ at 5 amps...
> > So, would I have any chance "in the hot place" of measuring the dissipation
> > factor of a poly MMC cap? Like <0.001 dissipation factor...
> > I guess I would have to detect the difference between 90 degrees and
> > 89.87856 degrees to find the dissipation factor...
> > Sounds doable but maybe someone out there has "been there, done that..." I
> > was just asked the question and "I" have not thought much on it cause I am
> > sleepy :o) Might need a step down transformer to get a really low source
> > Cheers,
> > Terry
> You may be able to do it on an incremental basis using bridge
> techniques. I am suggesting measuring the difference between two
> different types of capacitor, the one with the lowest esr score then
> going on to be the standard for a succeeding test which compares
> another. Hazy I know.