I suspect what he meant was a LCR/ESR meter; as in a single device which combines the two functions. These are common nowadays, they weren't always.
When ESR meters as commonly used in electronics repair were first devised, they showed two parameters: Capacitance and ESR. They worked on capacitors, period.
Some LCR Meters, particularly older laboratory units, use a substitution bridge to determine the value of the DUT and don't actually offer ESR or Tan δ parameters.
It is only later models which can use the magic of cheap microprocessors and multiple ADCs which can offer all the above in a single device, even giving all these parameters in one test.
Or is that not the question you were asking...?
mnem
It would be really surprising to find a LCR meter that is not able to measure Rs. Even if they have different name, ESR is equal to Rs. All LCR meters can measure Rs. Even the old one.
Personally, I think ESR meters are useless when you have a good LCR meter. Maybe ESR meters have better range ?
I'm not sure why people tend to believe ESR meters actually measure something that LCR meters can't. The LCR meter is the superior instrument, ESR meter only measure a subset (Rs and if you are lucky Cs) of what a LCR meter can do.
I think it's the test parameters, and the inconvenience. ESR meters typically operate at one of several... well, I can't even call it a standard, as there really is no such thing... lets call it "commonly used" frequencies dependent upon capacitance range, such that results from one design of ESR meter are comparable to another.
Calculating it from R
s means knowing what frequency the LCR meter is running at
right now, with this DUT, and it means that while you're diag-ing a PCB, every time you have to stop probing, pick up a pencil, and do some math to determine whether the cap is healthy or not.
ESR as it is used on a repair bench boils all that down to a simpler, more repeatable result of ESR vs Capacitance which you can just eyeball, gauge whether it's reasonable, and move on to the next suspect component. Having used the DE-5000 for a couple years now, and being able to compare results from both test functions, I find that the Tan δ function is much more reliable as far as giving a definitive Yes/No answer, simply because if you aren't sure based on the internal "chart" one develops when using any such device, you can usually find this parameter in a MFR's datasheet.
The entire table of "acceptable ESR values" that people refer to is based on a chart created by Dick Smith decades ago, which unfortunately didn't include a LOT of today's Low and Ultra-Low ESR capacitor product lines. So what has evolved since is kindof a mishmash of both. That in and of itself is the main reason ESR as measured by an ESR meter is pretty useless from an enginerding standpoint.
That is also, I think, part of the reason Robert and I butted heads on this so hard (and keep doing so)... he's a hardcore engineer who has kept up with his professional development, so has a lot invested in knowing what he's doing, while I'm a retired engineer who was (a) never really that good at any of it except keeping several hundred circuits from a design in my head and (2) had to fall back on service & repair for my livelihood because I couldn't hack the modern corporate crazy-factory that is commercial/industrial engineering.
Cheers,
mnem