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| LCR meter opinion |
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| Martin72:
Today I took several caps to work, starting to measure them, hope of finishing before the weekend starts. 1µ, 2.2µ, 3.3µ, 4.7µ and 8.2µF. First I took the 8.2µ . ....You can forget it at 100khz.. 8) Every LCR are showing nonsense at this frequency but that doesn´t surprise me much, I´ve expected it already. It´s simply not the frequency for µFs. Nevertheless, the values will be recorded in the table. The 16µf the keysight shows, the 39µf the ST2830 shows and the 9.1µF the DE5000 shows (Winner! ;D ) Martin |
| ogden:
--- Quote from: Martin72 on January 27, 2022, 09:17:33 pm ---First I took the 8.2µ . ....You can forget it at 100khz.. 8) Every LCR are showing nonsense at this frequency but that doesn´t surprise me much, I´ve expected it already. --- End quote --- No wonder! Reactance of 8.2uF capacitor at 100 KHz is 0.1941 Ohms. Lowest impedance of most LCR meters is 100 Ohms meaning by measuring such a big capacitor at such a high frequency you are throwing resolution of your instrument out of the window. Only reason to measure such capacitor at 100KHz is to show that you don't know what you are doing :) |
| Martin72:
I wasn't going to say it so directly, but now you have. Thank you... 8) |
| ogden:
Right. Check specs of decent meter like U1733C and you will see that measurement accuracy for capacitors larger than 20pF is better at 1KHz rather than 10KHz or 100Khz. Inductor measurements are what you need 100KHz LCR meter for. [edit] Decent primer of impedance measurement: https://www.keysight.com/zz/en/assets/7018-06840/application-notes/5950-3000.pdf |
| Martin72:
Point is, I know that, many others too. But some doesn´t and then they´re getting upset. Meter is crap, faulty, have issues, not recommendable, and so on... You doesn´t measure µF caps with more than 10khz, point. When cap manufacturers don´t so, why should you. Then the D-Factor thing... On keysight and DER LCR, the D-factor will displayed with maximum 3 digits after the comma. It´s a kind of nonsense for most of the foil caps. So mostly you´ll see only 0.000 in the display, when testing with the best suitable frequency. The D-factor is a calculated parameter, based on the measure. You can´t trust measurements with 100khz what µFs concerns - So you musn´t get upset, when the calculated D-factor rises up 80x in comparison to lower testfrequencies. Best example is the test with the 8.2µF on the keysight. It shows a dissipation of 4.26.....Before, with 10khz, it was 0.001... So it should be clear to everyone, what that means. Martin |
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