Products > Test Equipment

LCR meters - capacitance measurements at high frequency.

<< < (4/5) > >>

bdunham7:

--- Quote from: Traceless on May 14, 2023, 04:05:22 pm ---ESR with shorted leads seems stable but the other values are all over the place.

--- End quote ---

If the overall Z is very low, the measured signal values will be very low as well and the LCR meter will have trouble giving you a stable result since it has to do the math with a low, noisy signal.  Oddly, every LCR meter I've ever seen doesn't alert you to this and just tries to display the wildly varying results.  So if don't get a stable reading from a simple component, it is probably because of the signal level and noise.

exe:
Well, this is not a typical electrolytic cap, it's a solid polymer cap, those are, afaik, designed for SMPS and work at higher frequencies. Those are often specified at 100kHz and, I suspect, can handle much higher frequencies. Here, for example, an alu-cap is specified for ripple at 500kHz: https://www.chemi-con.co.jp/en/products/detail-condenser.php?part_number=HHXF250ARA151MHA0G

Traceless:

--- Quote from: mawyatt on May 14, 2023, 04:45:41 pm ---Attached are plots showing a frequency sweep for 10Hz to 1MHz with our IM3536 LCR meter. Plots were created by python routines we developed as a means to do these type sweeps, as well a Voltage sweeps and even some temperature sweeps. Don't want to distract from your thread, but  if interested will discuss and link.

--- End quote ---

I think the plots are interesting, feel free to place a link for further discussion! What is the resolution/step size of the sweep?


--- Quote from: bdunham7 on May 14, 2023, 06:09:36 pm ---
--- Quote from: Traceless on May 14, 2023, 04:05:22 pm ---ESR with shorted leads seems stable but the other values are all over the place.

--- End quote ---

If the overall Z is very low, the measured signal values will be very low as well and the LCR meter will have trouble giving you a stable result since it has to do the math with a low, noisy signal.  Oddly, every LCR meter I've ever seen doesn't alert you to this and just tries to display the wildly varying results.  So if don't get a stable reading from a simple component, it is probably because of the signal level and noise.

--- End quote ---

Thanks for the explanation. It's also reassuring to know that this seems to be a general problem with LCR meters and not some oddity with my particular model/unit.

@exe: Well spotted I did miss that the PSF series is actually a polymer cap. You find similar caps often used in the in the input power circuitry of mainboards/graphics adapters.

Edit: Actually I'm not even sure if they are (Polymer)-Electrolytics or not. I've seen similar capacitors declared as Polymer Aluminium Electrolytic Capacitor. The Nichicon PSF Datasheet I linked calls the PSF series "Conductive Polymer Aluminum Solid Capacitors". However if you look at the title page of the Nichicon document that lists the PSF series it says "Aluminum Electrolytic Capacitors".

sonpul:
The DE-5000 does not measure 270uFx16V Panasonic Os-Con at 10KHz and 100KHz. OL is displayed. As explained, this is because the formula for which the calculation is made perceives the capacitor as an inductance. That's why you have negative values.

mawyatt:

--- Quote from: bdunham7 on May 14, 2023, 06:09:36 pm ---.....Oddly, every LCR meter I've ever seen doesn't alert you to this and just tries to display the wildly varying results.  So if don't get a stable reading from a simple component, it is probably because of the signal level and noise.

--- End quote ---

The Hioki IM3536 does indicate when a measurement result is questionable, it also displays the Voltage across the DUT and the DUT Current. The Tonghui TH2820 also displays the DUT Voltage and Current, and both LCRs also have selective averaging, selectable drive voltage levels and driver impedance, all helpful for acquiring accurate results with certain DUTs.

These are very handy to keep an eye on when doing measurements, as it might help avoid a bogus result!!

Best,

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod