Electronics > Beginners
ESR Confusion
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bitseeker:
Capacitors have many properties and there are many tests that can be used to determine their well being. ESR is but one type of test to measure one property. Others may include, but are not limited to, capacitance, leakage, and Q factor. Take a peek at the data sheet for several types of capacitors and you'll see what I mean.

So, just because two capacitors have the same ESR doesn't necessarily mean they're equally good or bad. There may be other problems that aren't detected by an ESR measurement. However, if you didn't have an ESR meter, then you'd have even less information available to make a determination.
Terry01:
You'll find the ESR meter you have is better suited for measuring smaller smd caps, sort of. It measures @ 100kHz in series which is way too high for a 6500uf electrolytic. Also @ 100 kHz paralel measurment is better than series which is why i say "sort of".  The cap you measured should be tested closer to @ 120 Hz in series or there about. Have a read at this and it'll give you a better idea of what I mean. Get your head around the graph and you'll understand how i mean.

 www.techni-tool.com/site/ARTICLE_LIBRARY/BK%20Precision%20-%20How%20to%20Use%20an%20LCR%20Meter.pdf
wraper:

--- Quote from: Terry01 on June 27, 2018, 07:31:46 am ---You'll find the ESR meter you have is better suited for measuring smaller smd caps, sort of. It measures @ 100kHz in series which is way too high for a 6500uf electrolytic. Also @ 100 kHz paralel measurment is better than series which is why i say "sort of".  The cap you measured should be tested closer to @ 120 Hz in series or there about. Have a read at this and it'll give you a better idea of what I mean. Get your head around the graph and you'll understand how i mean.

 www.techni-tool.com/site/ARTICLE_LIBRARY/BK%20Precision%20-%20How%20to%20Use%20an%20LCR%20Meter.pdf

--- End quote ---
There is nothing wrong with measuring ESR at 100kHz for large capacitors unless your device measures capacitance at the same time and you need capacitance measurements as well.

--- Quote ---Get your head around the graph and you'll understand how i mean.
--- End quote ---
That graph is not about ESR.
Terry01:

--- Quote from: wraper on June 27, 2018, 08:26:04 am ---
--- Quote from: Terry01 on June 27, 2018, 07:31:46 am ---You'll find the ESR meter you have is better suited for measuring smaller smd caps, sort of. It measures @ 100kHz in series which is way too high for a 6500uf electrolytic. Also @ 100 kHz paralel measurment is better than series which is why i say "sort of".  The cap you measured should be tested closer to @ 120 Hz in series or there about. Have a read at this and it'll give you a better idea of what I mean. Get your head around the graph and you'll understand how i mean.

 www.techni-tool.com/site/ARTICLE_LIBRARY/BK%20Precision%20-%20How%20to%20Use%20an%20LCR%20Meter.pdf

--- End quote ---
There is nothing wrong with measuring ESR at 100kHz for large capacitors unless your device measures capacitance at the same time and you need capacitance measurements as well.

--- Quote ---Get your head around the graph and you'll understand how i mean.
--- End quote ---
That graph is not about ESR.

--- End quote ---


When would a large electrolytic be used @ 100kHz? What would happen if it was? I have a good machine that measures @ both 100 or 100k so which is correct?

If that graph is not for ESR did they just make it for a laugh or does BK not know nothing?
wraper:

--- Quote from: Terry01 on June 27, 2018, 10:06:10 am ---If that graph is not for ESR did they just make it for a laugh or does BK not know nothing?

--- End quote ---
BK is fine, something wrong on your side. READ again, LCR measurement guidelines, not ESR. LOW ESR capacitor ESR usually is specified at 100kHz, be it small or big capacitor. General purpose capacitor ESR may be specified either at 120/100Hz or 100kHz. In both cases capacitance is usually specified at 120Hz or 100Hz. In practice there is no need to check ESR at 120Hz when checking components, unless you want compare apples vs apples with figure in a datasheet.
Here you go, up to 18000uF with ESR specified at 100kHz. http://www.chemi-con.com/upload/files/5/1/74811667552d6c4d41a84c.pdf

--- Quote ---When would a large electrolytic be used @ 100kHz?
--- End quote ---
Say SMPS.


--- Quote ---If your LCR meter allows it, measure the impedance
at the application frequency if you can. Seeing the
impedance magnitude in ohms helps you use your
intuition—and the phase angle tells you quickly if
you have a pure reactance or a mixture of resistance
and reactance.
--- End quote ---
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