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| East Tester ET4410 ESR Measure |
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| The Electrician:
Here are a couple of plots vs frequency of parameters of a 1000uF 16v Rubycon capacitor. The first plot shows the impedance magnitude |Z| (green) and ESR (yellow) over a frequency range of 100 Hz to 5 Mhz. You can see that starting at the left at 100 Hz, |Z| decreases with increasing frequency as we would expect for a capacitor, but somewhere before 100 kHz where marker B is, |Z| begins to increase. A |Z| that increases with frequency is behavior that we would expect from an inductor, and that increase is due to the ESL (equivalent series inductance) of the capacitor. The capacitance of the capacitor resonates with the ESL of the capacitor just below (it's at marker A in the second image) the frequency where marker B is; this is called the self resonance frequency of the capacitor. At frequencies above the SRF (self resonance frequency), an LCR meter which is set to measure capacitance will show a reading which is negative, because above the SRF the impedance of the capacitor is inductive. The second plot shows the same yellow curve of the ESR vs frequency, but now the green curve is the phase angle of the impedance of the capacitor being measured. The scale of the linear display is -90 degrees at the bottom, +90 degrees at the top. The green curve starts at the left (100 Hz) near the bottom, so at low frequencies the phase of the capacitor's impedance is nearly -90 degrees. As the frequency increases, the phase moves upward (but is still negative--capacitive in other words) until at marker A (65.027 kHz), the phase has reached zero degrees--the impedance is purely resistive. Continuing up in frequency, the phase angle continues to increase toward +90 degrees, staying positive, which means it's inductive. Notice the behavior near 100 kHz; the phase is close to zero degrees, and it can't be -82.7 degrees. |
| mawyatt:
Nice plots :-+ Best |
| Martin72:
--- Quote from: Martin72 on July 29, 2022, 08:46:22 pm ---Today a electrolytic cap on my ET4410, same cap then on monday with the lcrs on work. It´s a low esr type from panasonic, 100µF/35V. Results with 120hz, 1Vrms, series: C: 102.96µF Xc : -12.882 Ohm D: 0.0208 Q: 47.388 Phase: -88.79° ESR: 0.2699 Ohm (stable.. ;) ) --- End quote --- Results keysight U1733C: 103.65µF D: 0.018 Q: 59.1 Phase: 89.0° ESR: 0.273 Ohm Xc: forgotten Results ST2830: 103.30µF D: 0.0198 Q: 50.47 Phase: 88.86° ESR: 0.255 Ohm Xc: forgotten I would say, all three LCRs are close together. The panasonic 1000µF cap on 100khz: Keysight : OL ST2830: -32.57µF, 0.0154 Ohm (ESR), Q 3.16, D 0.317, forgotten the phase (tomorrow) |
| The Electrician:
--- Quote from: Martin72 on July 31, 2022, 07:49:18 pm ---Yepp, Not so bad for a cheap one. Test a panasonic FM electrolyt cap, 1000µF/25V on 100khz a few minutes ago. ESR 0.034 Ohm D 0.128 Xc -0.267 Ohm Q 7.81 Phase - 82.7° And cap....5.95µF ;) --- End quote --- This is the set of measurements from reply #103 that I think are not right. In reply #112 today you gave some numbers that are from a Panasonic 1000 uF cap. "The panasonic 1000µF cap on 100khz: Keysight : OL ST2830: -32.57µF, 0.0154 Ohm (ESR), Q 3.16, D 0.317, forgotten the phase (tomorrow)" Is this the same cap as in the quote above? These numbers are quite different. What meter did you use to make the original measurements in the quote from reply #103? Can you make measurements of the LCR meters at work of this Panasonic 1000 uF cap? |
| Martin72:
Hi, First measurements were taken at home on the ET4410, the last posted were at work on calibrated LCRs like keysight U1733C and Sourcetronic ST2830. Same caps used like home, the 100 and 1000µF from panasonic. Forgot the Xc parameter, so repeat it in the next days. |
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