Products > Test Equipment
East Tester ET4410 ESR Measure
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The Electrician:
Your problem is undoubtedly a matter of signal to noise ratio.

LSR meters operate as Timfox explained in post #13.  You can also find a good in depth explanation in the Agilent Impedance measurement handbook.  Google "impedance measurement handbook"

When you measure a capacitor, the meter applies a sine wave of whatever the nominal voltage is (1 volt for your measurement) and extracts the in phase and quadrature components of the resulting current.  The ratio of the two components is equal to the value of D.

So if your capacitor is low loss, the real part of the current is going to be very small.  For example, if the cap has a D of .001, the meter will be trying to measure a very small current/voltage (microvolts).  When the measured value of D < .001 (or equivalently, Q>1000), low cost meters are going to have problems.

A good meter will know when it's measurement is in the noise, and will not show very many digits for the result.  Watch out for that clue that the measurement is "iffy".  For example in reply #9 your measurement shows 4 digits for the capacitance, but only 2 digits for the ESR.

In reply #15, the 10 kHz measurement of ESR shows a value of .0085 ohms.  This is impossible.  The value of Q is Xc/ESR; that measurement would imply a Q of about 188000.

The Hioki IM3570 can be set to show 7 digits.  This is well beyond the accuracy of the instrument but it's handy for matching components, and watching drift with temperature.  Here's what I get when I measure a 10 nF silver mica capacitor, which is a very low loss capacitor, at 10 kHz:



The capacitance is shown as 7 digits, but only about 5 of them are stable.  ESR (Rs) is shown with 6 digits, but only the leading 2 digits are stable.  Note that the Q is about 6000; this is approaching the capability of the instrument.  When the Q>10000, the Hioki won't even show a value; it just indicates an out of range value.

I think that your East Tester just can't cope with very low loss capacitors.  I've noticed that some of the hand held meters I have exhibit the same limitations.



Martin72:
@mawyatt
You take the knife, hit it in my heart and turning it around.... ;)
I´ve sold it not long time ago and I could bite in my a*** I did it... :P
The Electrician:

--- Quote from: Martin72 on July 14, 2022, 10:53:38 pm ---@mawyatt
You take the knife, hit it in my heart and turning it around.... ;)
I´ve sold it not long time ago and I could bite in my a*** I did it... :P

--- End quote ---

I measured the silver mica cap from reply #20 on my DE5000.  Here's what I got.

At 1 kHz, the value of the cap is good. D is 0.000, Q is OL, ESR is 1.86

At 10 kHz, the value of the cap is correct.  D is 0.000, Q is OL, ESR is 0.18  :-- |O

These two ESR values for this very low loss capacitor are completely bogus.  It's too bad the DE5000 doesn't recognize that it's bogus and refuse to show a value.  This is very misleading behavior.  A user of low cost LCR meters needs to know that as soon as the value of D is less than .001, the measurement will be noisy.  The Gold standard LCR meter is the Keysight E4980A (@ $20000) which can get measurements down to a D of about .0001 with maybe 50% accuracy at the limit.

Your East Tester is better than the DE5000.

I found a 10 nF polystyrene capacitor and measured it with the Hioki IM3570:



This capacitor is somewhat beyond what even the top of the line Hioki can do.  Notice that the capacitance is still given with 7 digits, but the ESR (Rs) has only one stable digit, and it is suspect.  The DE5000 and other handhelds and even low cost bench meters won't be able to measure ESR of such low loss capacitors; but they can still correctly measure the capacitance.
The Electrician:

--- Quote from: Martin72 on July 05, 2022, 10:12:02 pm ---Hi,


Taking a different cap, an Elko with 1000µF, ESR is stable displaying.
Are the caps bad, is it because of the low value of 10nf...
Will investigate it further, with other caps.

Martin

--- End quote ---

The measurement is stable with electrolytics because they are lossy; their D is never going to be as low as .001, or even close to that.
Martin72:

--- Quote ---Your East Tester is better than the DE5000.
--- End quote ---

Yap, it´s not the badest one as it got 16 selectable frequencies up to 100khz, output up to 2Vrms, Bias, 30 or 100Ohm selectable output resistance and finally a basic accuracy of 0.2% .
And the basic RCL measures it performs very well, but the "secondary parameter" thing...
A look into the ET4410 offers a good design of the circuits, but you can´t get schematics for it.
As I´ve asked for it, they (East-Tester) immediately send me the SCPI commands.
Now I´ve asked of the ESR thing at the beginning of the week and nothing happens.
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