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East Tester ET4410 ESR Measure
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The Electrician:
There's something odd about that Panasonic 1000 uF cap.  Besides making the measurement on all the meters you have access to at 100 kHz, would you please make a measurement at 100 Hz, 1 kHz, and 10 kHz on the best meter.

Edit: Another thing you might do is find some other 1000 uF electrolytic capacitors and make a few measurements at 100 kHz, to see if they are much different then the Panasonic one.
mawyatt:
"The panasonic 1000µF cap on 100khz:
Keysight : OL
ST2830: -32.57µF, 0.0154 Ohm (ESR), Q 3.16, D 0.317, forgotten the phase (tomorrow)"

Does the negative capacitance reading at 100KHz of the 1000uF Panasonic indicate an inductive reactance due to ESL, which would be past the series resonate frequency? If so, then the phase should be positive.

Best, 
mawyatt:

--- Quote from: Martin72 on August 01, 2022, 08:28:31 pm ---
--- Quote from: Martin72 on July 29, 2022, 08:46:22 pm ---Today a electrolytic cap on my ET4410, same cap then on monday with the lcrs on work.
It´s a low esr type from panasonic, 100µF/35V.

Results with 120hz, 1Vrms, series:

C: 102.96µF
Xc : -12.882 Ohm
D: 0.0208
Q: 47.388
Phase: -88.79°
ESR: 0.2699 Ohm (stable.. ;) )

--- End quote ---

Results keysight U1733C:
103.65µF
D: 0.018
Q: 59.1
Phase: 89.0°
ESR: 0.273 Ohm
Xc: forgotten

Results ST2830:

103.30µF
D: 0.0198
Q: 50.47
Phase: 88.86°
ESR: 0.255 Ohm
Xc: forgotten

I would say, all three LCRs are close together.
The panasonic 1000µF cap on 100khz:
Keysight : OL
ST2830: -32.57µF, 0.0154 Ohm (ESR), Q 3.16, D 0.317, forgotten the phase (tomorrow)

--- End quote ---

Shouldn't this 100uF cap measured at 120Hz have a negative phase?

Best,
The Electrician:

--- Quote from: mawyatt on August 01, 2022, 11:48:43 pm ---"The panasonic 1000µF cap on 100khz:
Keysight : OL
ST2830: -32.57µF, 0.0154 Ohm (ESR), Q 3.16, D 0.317, forgotten the phase (tomorrow)"

Does the negative capacitance reading at 100KHz of the 1000uF Panasonic indicate an inductive reactance due to ESL, which would be past the series resonate frequency? If so, then the phase should be positive.

Best,

--- End quote ---
There a number of things that make me think something's wrong, either with the capacitor itself, or the measurement.

The plot of the impedance phase of a 1000 uF cap in reply #110 was intended to show that the self resonance of the typical 1000 uF electrolytic is near 100 kHz, and the phase is near zero degrees.  I don't think it can be vary much from zero, plus or minus.

The measurements in reply #103 gave this for the phase: "Phase - 82.7°".  Is that a minus sign or is it a hyphen?  Whichever it is, I don't think the magnitude of the angle can be as great as 82.7  Also the Q is given as 7.81 (the measurement reported today gives it as 3.16); I measured several 1000 uF electrolytic caps, and I can't find any with Q that high.

Would you measure a few 1000 uF electrolytics and see what you get for Q at 100 kHz?

mawyatt:

--- Quote from: The Electrician on August 02, 2022, 12:11:29 am ---Would you measure a few 1000 uF electrolytics and see what you get for Q at 100 kHz?

--- End quote ---

The only 1000uF electrolytic cap we have is an inexpensive Beryl 1000uF @ 16V RC(M) 2110 105C type.

https://datasheet.lcsc.com/lcsc/1912111437_BERYL-Electronic-Tech-RC016M102LO10-16TH-2A1E_C357639.pdf

Measured with Tonghui TH2830, Hioki IM3536 and DE5000. Very quickly done without calibration or a proper warmup.

TH2830         100Hz              1KHz              10KHz             100KHz 
C                913uF               874uF             1,117uF         -105uF
ESR             0.109               0.051               0.048              0.057
Angle           -86                   -74                  -16                  +15
D                 0.06                0.28                 3.55                 3.80

IM3536       
C               911uF                878uF              1,243uF         -66uF
ESR           0.120                 0.056               0.053             0.063
Angle          -86                     -73                  -14                +21
D               0.07                   0.31                  4.14              2.56

DE5000
C               923uF                875uF              OL                  -101uF (computed from Ls)
ESR           0                        0.04                                       0.04 (Rs)
Angle           -87                      -77                                     +19
D                0.06                   0.23                                     2.89 

Appears the SRF is ~24KHz (Z magnitude angle ~0). Note the 100KHz measurement with DE5000 was with Ls and Rs, C computed from ~ 1/[(2*pi*100KHz)^2 * Ls]

Anyway, this seems like a typical low end cap, not sure about the Panasonic Martin measured tho, maybe a special Polymer type or something?

Best,       
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