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| East Tester ET4410 ESR Measure |
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| mawyatt:
Getting negative values for ESR and D is not difficult, we just did so with a 10nF Polystyrene at 10, 100 and 1KHz. If you look at the impedance angle, the phase drops slightly below -90.0 degrees which is obviously impossible for a real capacitor with a simple series C and ESR model. So this is just dancing around the limits of measurement for a particular instrument and DUT, where a higher measurement frequency increases the DUT current and lowers the instrument transimpedance gain (lower feedback resistor that senses the DUT current) moving back into a region where the instrument can provide a meaningful measurement, and why we mentioned such. Best, |
| mawyatt:
--- Quote from: TimFox on July 26, 2022, 11:05:53 pm ---The negative D value reminds me of my missed Nobel prize when I measured a negative noise factor on a very-low-noise RF amplifier due to a slight miscalibration of the apparatus. --- End quote --- Reminds me of a couple physicist searching for the magnetic monopole long ago. They sent up a detector in a balloon and when developing the photographic plates from the detector found a trace and claimed it was the elusive magnetic monopole. They also missed the Nobel when later it was discovered the plate was installed 90 degrees out of phase...oops On a closer note, we had a similar case when IBM provided a new HICUM SiGe bipolar model, under certain conditions this model would negate some of the noise from the driving source. They didn't win a Noble either, more like a pie in the face when we notified them about the magic transistor!! Best, |
| indman:
--- Quote from: The Electrician on July 26, 2022, 09:01:40 pm ---Page 41 of that manual shows the adjustment. If that adjustment is taken into account, the behavior of the DE5000 is accounted for. --- End quote --- I've read this guide before and it introduces even more questions than answers! "Secondary Parameters Accuracy: Az = impedance (Z) accuracy Definition: Q = 1/D & Rp = ESR * (1+1/D2) D value accuracy: Dz = ± Az *(1+D) ESR accuracy: Rz= ± Zm * Az (Ω) ie., Zm = impedance calculated by 1÷(2πƒC) or 2πƒL Phase angle Θ accuracy: Θz= ±(180/ππππ)*Az (deg)" What should I understand from this? What is Az - an unknown impedance value, which, under the condition D<0.1, is characterized by the reactance of the capacitor? In what units is it calculated? And how does this explain the "fantastic" results secondary parameters when measuring high-quality polypropylene capacitors? Why does the manual not specify the accuracy and tolerance in % as it is done for the primary parameters L-C-R? It turns out that I myself have to conduct experiments and determine the degree of reliability of the testimony? Or does the device manufacturer have to do it? And if I don't have a "TH/ST" class device to compare readings with? |
| Martin72:
--- Quote ---And if I don't have a "TH/ST" class device to compare readings with? --- End quote --- Even when you got one, it won´t bring you any further as they also can´t measure/displaying it correctly. Example, mentioned before, the 10nF mica cap I´ve measured it with the ET4410, the U1733C from keysight and the ST2830 from sourcetronic. All meters measured the capacity correctly inbetween their accuracies and inbetween the tolerance of the cap. All meters measured the Xc correctly. But none measured the expected ESR correctly. Expected means in this case the calculated one, based on the values of the Tan phi from the spec. It should be in the range of appx 16ohms at 1khz. The ET4410 displays appx 5 ohms, the ST2830 appx 3 Ohms and the keysight "freaks out", displaying something and blinking all the time. The most probably reasons why you´ll find it here in this thread. So for me there are several conclusions "avaible". 1.) Can´t expect to have it all even when you spend 1000 bucks or more for a LCR. 2.) The "secondary" measure functions of the "cheapos" (including the 1000 bucks or more) like D or ESR are (probably, will test it soon) trustable for caps with "bad" losses like electrolytic ones. 3.) When you wil get in a situation (as a hobbyist) to know exactly the losses/ESR of a high Q cap? Isn´t it more practical to know the ESR of a electrolytic cap which the meters could display trustable? 4.) Developers choosing a cap for their circuit design according to the specs of the manufacturer, not by measuring it before. The only exception is to know the exact capacity (for filters) - And capacity every not too cheap meter can measure it correctly. So why we private ones will go further...Buy a cap from a known manufacturer according to the specs it got and you need and that´s it. 5.) Knowing the exact ESR is in the most cases interesting by electrolytic caps (switching power supplies) when you must repair something. And the ESR of these ones even a cheaper meter should measure it. |
| indman:
--- Quote from: Martin72 on July 27, 2022, 10:49:39 pm ---2.) The "secondary" measure functions of the "cheapos" (including the 1000 bucks or more) like D or ESR are (probably, will test it soon) trustable for caps with "bad" losses like electrolytic ones. --- End quote --- I agree with this 100%! This information should have been placed in the documentation for the device, and not to invent fantastic formulas with unknown variables that confuse the user even more.;) If we follow your logic, then the measurement of secondary parameters for high-quality non-electrolytic capacitors for devices of this class is NOT RELIABLE and is only for evaluation and familiarization purposes,what does the status of an amateur meter mean! For me, this conclusion is obvious and so far no one has convinced me otherwise. --- Quote from: The Electrician on July 26, 2022, 10:37:16 pm ---Here is an example of how extremely low loss capacitors can overwhelm even the best LCR meters. On eBay are offers for very high performance capacitors from Ukraine left over from the USSR military. I bought some of them and this is a .5 uF polystyrene capacitor. --- End quote --- Name the marking of this capacitor or show a photo of it, if possible. I'll look for the same one in my stocks.. :) |
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