I have one, and it has lots of modes, and for testing the ESR of caps, I'm not really sure about the right settings and readings.
I'm powering it with from a linear bench PSU btw, so it's a nice clean proper voltage.

Here's a look at the meter, jump to 22min to see some capacitor testing, mjlorton was also new to LCR meters at the time.

I know caps are made for different frequency ranges and voltages.

When I try testing a cap, I'll go to Cs (series capac.), and on the lower display I'll choose ESR. The I can choose the frequency of 100Hz, 1kHz, 10kHz or 100kHz.

Now lots of times, on larger caps, like over 100uF. At lower freq's it might read about right . But then I can't get a Cs reading @ 10kHz or 100kHz, it just says OL, and the ESR won't show up either. In general the Cs drops lower as the freq goes up. But IDK if it reading OL really means the cap is USLESS at that freq, or not ??


However in those cases, I've just been switching to Rs (series resistance) and I can always get a Rs value at 100kHz, and rightly or wrongly I've been calling that the ESR @100kHz

Like for example I have a 10uF 16V cap. s and ESR are displayed on same screen, Rs gets a whole screen to it's self
@100Hz Cs=9.977uF ESR=7.0 and Rs=7.50
@1kHz 9.118uF ESR=2.56 Rs=2.585
@10kHz 7.922 ESR=1.55 Rs=1.562
@100kHz 4.27uF ESR=1.19 Rs=1.191


Now with a random 330uF 35V cap
@100Hz Cs=315.8uF ESR=0.2 Rs=0.24
@1kHz 304uF ESR=0.13 Rs=0.138
@10kHz Cs=OL, ESR= ---- Rs=0.121
@100kHz Cs=OL, ESR= ---- Rs=0.116

Now with a 3300uF 6.3V cap from a computer SMPS output, so certainly made for 100kHz
@100Hz Cs=2.93mF ESR=0.0 Rs=0.03
@1kHz Cs=OL, ESR= ---- Rs=0.024
@10kHz Cs=OL, ESR= ---- Rs=0.023
@100kHz Cs=OL, ESR= ---- Rs=0.025

 

Always do a short/open calibration before using. Use a lead for the short test because they are Kelvin clips.

You can look at datasheets for capacitance/type of capacitor/ to get an idea of what the ESR should be.

A capacitance change of 20% from nominal would also be an indicator of a bad cap.

Electrolytic capacitors used in switching power supplies are special. They should have a low ESR at the higher frequencies.

 

A short test reads as OL and ----ESR

Sometimes it will read a cap, like right now a 330uF 200V, that must be bad, reads as
@100Hz Cs=301.1uF ESR=1.0 Rs=1.01
@1kHz Cs=243, ESR=0.72 Rs=0.730
@10kHz Cs=108.1, ESR=0.55 Rs=0.561
@100kHz Cs=10.96uF, ESR=0.47 Rs=0.473


I have another 330u 200V cap, thats good, it reads as
@100Hz Cs=306.1uF ESR=0.1 Rs=0.16
@1kHz Cs=301, ESR=0.11 Rs=0.113
@10kHz Cs=OL , ESR=---- Rs=0.104
@100kHz Cs=OL , ESR=---- Rs=0.098

IDK but I guess it must be fine to treat Rs as ESR for caps

 

There should be a
short and open calibrate where it goes through each frequency.

My little Agilent 1733c. Hold Cal; Open shows up on display. push cal. Open cal is preformed.
then short appears. You short probes and press cal again.
Goes through all frequencies.
Now your ready to measure.

ESR of open just keeps trying to range
ESR of a short reads about 0.6

At work I had the big boy with bias and oscillator level that you had to adjust

 

Now lots of times, on larger caps, like over 100uF. At lower freq's it might read about right . But then I can't get a Cs reading @ 10kHz or 100kHz, it just says OL, and the ESR won't show up either. In general the Cs drops lower as the freq goes up. But IDK if it reading OL really means the cap is USLESS at that freq, or not ??

That behaviour is highly dependent on the capacitor itself (geometry, dielectric compound, temperature, frequency, etc.). Electrolytic capacitors tend to have an increase in dielectric and inductive losses which become predominant when the frequency increases. Also, the manufacturers usually specify the dissipation factor (D or tan δ) which is a better round number that involves ESR and the reactance of the capacitor.

Several references mention that

https://www.illinoiscapacitor.com/pdf/Papers/impendance_dissipation_factor_ESR.pdf
http://rubycon.co.jp/en/products/alumi/pdf/Performances.pdf
http://www.kemet.com/Lists/Technica...capacitor drops to 37 uF- 30 uF- or lower.pdf

https://www.avnet.com/wps/portal/ab.../understanding-esr-in-electrolytic-capacitors