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LCR meter opinion
indman:
The DE-5000 has problems measuring high quality film capacitors at 100kHz and no one has convinced me otherwise. Best of luck with the measurements!
Martin72:
When you don´t use the right frequency for testing, it´s not the problem of the lcr.
Here a couple of datasheets snippets from high quality foil capacitors, their dissipation factors(see attachments below).
They all have one thing in common, 100khz only for caps max 100nF(except 383 series from vishay).
I can understand your concerning, it shows something at 100khz you can´t trust.
But that is not important, it´s not a issue, a showstopper, a problem.
Because you don´t test mikro-farads with 100khz, sounds simple, is simple.
When the DE5000 would have this behaviour on the right frequency, then it will be a problem, a isssue, a no go thing.
But it don´t have it.
And it´s getting "better":
DE5000 and the unlikely more expenisve U1733C from keysight have one thing in common, the D-factor display is nearly useless for foil-caps because of the poor display resolution(lowest value 1x10-³ = 0.001).
The ST2830 fits better.
Martin
nctnico:
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.
Loss factor is frequency dependant so it will show different values at different frequencies. How much different depends on the dielectric losses which can vary wildly with frequency depending on the dielectric material used:
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/dielectric-loss
https://www.intechopen.com/chapters/39574
In a real world scenario I would like to know how a several uF capacitor behaves at higher frequencies (heck, your LCR meter likely has a several uF capacitor at the input to seperate the DC bias from the signal and the designer very likely specified / measured them to assess fitness for the purpose). An LCR meter typically covers the lower frequencies where a network analyser typically doesn't work very well.
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?
For example: this 10uf 0402 capacitor is specified up to several GHz: https://www.murata.com/en-eu/products/productdetail?partno=GRM155D70G106ME18%23
I did some testing with my own LCR meter (GW Instek LCR-821 to be precise; an older higher end model) and I measured some polyester/MKT capacitors: 1.5uf, 1.8uf and 2.2uf from my parts bin (unfortunately the largest I have around is 2.2uf). They all read to within a few % of error from 100Hz to 200kHz using Kelvin clips. With every frequency change I performed an offset calibration (with a piece of busbar for the short test). As expected the dissipation factor changes with frequency. The 2.2uf goes from 0.0011 (@100Hz) to 0.043 (@ 200kHz).
Martin72:
--- 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.
Same when using a frequency range of the meter.
When you want to do measures with a frequency that covers all ranges of the meter, you must choose a frequency that will do so, according to the specs of the meter.
When you want to measure "higher" capacities with e.g 100khz for what reasons ever, you must use a meter which can do that.
It´s not a fault of the meter you used before.
When you test a cap beyond it´s specs with a meter beyond it´s specs, what do you expect to get ?
Vgkid:
My LCR meter has a bunch of calculations to calculate the measured accuracy.
Most high end LCR / cap meters should use a accuracy formula...
the easy to use calculator for my unit:
https://www.ietlabs.com/notes/digibridge_accuracy_calculator
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