Products > Test Equipment
Hioki IM3570 LCR & Impedance Analyzer
Martin72:
--- Quote from: KungFuJosh on September 12, 2024, 05:13:42 pm ---If the cap only shows the correct C value at 120Hz, why wouldn't you take an ESR measurement there too?
--- End quote ---
Because the ESR at 120 Hz is not so interesting.
The lowest possible ESR plays a role in switched power supplies, hence the 100 kHz measurement frequency.
indman:
--- Quote from: KungFuJosh on September 12, 2024, 05:13:42 pm ---I still think is weird. If the cap only shows the correct C value at 120Hz, why wouldn't you take an ESR measurement there too?
--- End quote ---
This seems logical and the RLC meter allows you to measure this. But what will the ESR result at 120Hz give you?
It will be highly dependent on the reactive constituting of the capacitor.
It is for this reason and because the natural resonance frequency of standard aluminum electrolytic capacitors is usually less than or close to 100kHz. I.e.. to measure ESR, the frequency of the oscillator must be tuned until the minimum reading at the natural resonance frequency Z(w) = ESR is obtained. In such a case, the result will not depend on either the capacitance or the equivalent series inductance.
In addition, the ESR of capacitors is of great practical importance for impulsed devices that operate at frequencies much higher than 100Hz, that is, at tens or hundreds of kilohertz. :)
P.S Martin72 already beat me to it, but I didn't copy what he said. :D
I also forgot to add that at a frequency of 120 Hz a very important parameter of the quality of the capacitor is also measured - this is the loss tangent or D (dissipation factor). For high-quality electrolytic capacitors, it should not exceed a value of 0.09-0.10.
KungFuJosh:
Thank you both! More specific things to test at specific frequencies. Fun! 😉
KungFuJosh:
Here's the cap sweep done a couple different ways. I used the exported data from the "LCR Meter Sample Application" to create the Excel spreadsheet, and then the data exported directly from the IM3570 to create spreadsheet v2. The data appears the same on the chart, despite being separate test runs.
indman:
--- Quote from: KungFuJosh on September 12, 2024, 08:17:20 pm ---Here's the cap sweep done a couple different ways. I used the exported data from the "LCR Meter Sample Application" to create the Excel spreadsheet, and then the data exported directly from the IM3570 to create spreadsheet v2. The data appears the same on the chart, despite being separate test runs.
--- End quote ---
In confirmation of the above theses about the resonant frequency of the capacitor, your first screenshot shows very well that after 38kHz the capacitance 1mF miraculously acquires the properties of inductance. :)
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