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LCR meter opinion

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nctnico:

--- Quote from: Martin72 on January 29, 2022, 12:13:20 am ---
--- Quote ---Bottom line: saying LCR meter can't measure capacitors at higher frequencies doesn't make sense. It screams measurement error to me.
--- End quote ---

I don´t tell that.  ;)

It´s important to do measures according to the specs for getting more or less constant reproduceable results you or others can work with.
Specs what the selected cap concerns and what the measure device concerns.
Measuring values with a frequency higher/lower than the frequency on which the values based according to the datasheet means simply, that what you measure then is not specified.

--- End quote ---
No. You are grossly mis-interpreting capacitor specifications! According to your logic capacitors should only be used at the frequency stated in the datasheet which is completely bonkers. The real problem with one or two datapoints in the datasheet is that you need an LCR meter to get yourself more datapoints if you are interested in those. Keep in mind that manufacturers want their parts to look good so they are more likely have left high dielectric loss figures out of the tables you posted for cosmetic reasons rather than not being able to measure them. OR that the losses at the maximum voltage rating exceed the thermal rating of the part; but that doesn't rule out using a higher voltage (physically larger) part at a lower voltage but higher frequency. The latter would require you to use an LCR meter to measure the losses at the maximum frequency you want to use the capacitor at.

And again, your wildly varying test results are measurement errors. I'm pretty sure that an LCR meter designed to go up to 100kHz can measure a capacitor with a value in single digits uf within a few percent of error (assuming the LCR meter has a reasonable base accuracy) IF the LCR meter is used properly.

ogden:

--- Quote from: nctnico on January 28, 2022, 11:43:15 pm ---Sorry but you are not convincing me by showing capacitor specifications. It is not like you can't use these capacitors above the frequencies used to measure / specify them.

--- End quote ---

We talk about measurements, not use. Specified at some frequency does not mean it can't be used or won't work at higher frequencies. Thou if you want *assured* performance at higher frequency than your capacitor specified at, you are using wrong component.


--- Quote ---Bottom line: saying LCR meter can't measure capacitors at higher frequencies doesn't make sense. Your results scream measurement / equipment error to me. Are the Kelvin clips actually Kelvin clips? How about shielding?

--- End quote ---

Look into DER EE5000 datasheet - at 100KHz frequency max 10uF, 3% accuracy. Keysight U1733C has 5% accuracy for up-to 20uF at 100KHz. It's because of LCR meter, not capacitor limitations. Isn't that obvious for you already?


--- Quote ---For example: this 10uf 0402 capacitor is specified up to several GHz: https://www.murata.com/en-eu/products/productdetail?partno=GRM155D70G106ME18%23

--- End quote ---

Capacitor indeed can be measured at any frequency, even up-to several GHz, but not using common LCR meter! For that impedance analyzers are used, like: https://www.hioki.com/global/products/lcr-meters/3-ghz/id_6618

nctnico:

--- Quote from: ogden on January 29, 2022, 08:53:38 am ---
--- Quote from: nctnico on January 28, 2022, 11:43:15 pm ---Sorry but you are not convincing me by showing capacitor specifications. It is not like you can't use these capacitors above the frequencies used to measure / specify them.

--- End quote ---

We talk about measurements, not use. Specified at some frequency does not mean it can't be used or won't work at higher frequencies. Thou if you want *assured* performance at higher frequency than your capacitor specified at, you are using wrong component.

--- End quote ---
That is what I would call a contradiction. You will want assured performance in any application!

I gave a perfect example which you appearantly have missed. Again: If my application doesn't need a low loss-factor at a given frequency, I'm not going to care that the loss factor isn't specified for a certain capacitor at that frequency. Just check the material specifications (graphs and links have been posted before) and measure a few samples to make sure what kind of ball-park figure the value is at to prevent potential problems.

Think about how audio equipment uses electrolytics in the audio path. In consumer equipment none of those capacitors are specified at 20kHz.


--- Quote ---
--- Quote ---Bottom line: saying LCR meter can't measure capacitors at higher frequencies doesn't make sense. Your results scream measurement / equipment error to me. Are the Kelvin clips actually Kelvin clips? How about shielding?

--- End quote ---

Look into DER EE5000 datasheet - at 100KHz frequency max 10uF, 3% accuracy. Keysight U1733C has 5% accuracy for up-to 20uF at 100KHz. It's because of LCR meter, not capacitor limitations. Isn't that obvious for you already?

--- End quote ---
You are repeating exactly what I'm stating! And the conclusion is the same: measurement error in the case where an 8.2uf capacitor shows results which are way off (far outside what you would expect based on the LCR meter specification). In the end an LCR meter is less easy to use than it appears.

ogden:

--- Quote from: nctnico on January 29, 2022, 11:30:53 am ---
--- Quote from: ogden on January 29, 2022, 08:53:38 am ---
--- Quote from: nctnico on January 28, 2022, 11:43:15 pm ---Sorry but you are not convincing me by showing capacitor specifications. It is not like you can't use these capacitors above the frequencies used to measure / specify them.

--- End quote ---
We talk about measurements, not use. Specified at some frequency does not mean it can't be used or won't work at higher frequencies. Thou if you want *assured* performance at higher frequency than your capacitor specified at, you are using wrong component.

--- End quote ---
That is what I would call a contradiction. You will want assured performance in any application!

--- End quote ---
Application?  :-//    It does not matter - opponent can't read on purpose or not, I am out of such kind of discussion. GLHF

nctnico:

--- Quote from: ogden on January 29, 2022, 05:20:22 pm ---Application?  :-//    It does not matter - opponent can't read on purpose or not, I am out of such kind of discussion. GLHF

--- End quote ---
Now you are being silly.

Back to the core of the discussion: Are you seriously going to suggest that a reading which is several 100's of percent off from what is expected (based on what the test equipment is capable of) indicates that the piece of test equipment is unsuitable (despite it's specifications saying it is) and not a case of user error?

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