DER EE DE-5000 LCR Meter

[Ron Reeland]

Hi:
I am trying to learn how to use my DE-5000 LCR meter, especially the capacitor testing parameters. I first tested a Cornell-Dubilier .1 ufd, 2000 volt, 10% polypropylene capacitor #942C20P1KF. The meter displayed a capacitance of .100 ufd, dissipation factor 0.000, ESR .01 ohm, phase angle -90 degrees. Test frequency of 100 KHZ. I was very pleased at these results.

But there seems to be an issue with the Quality Factor (Q) reading. The display reading will not settle down. It will wander down from 1200 to 908 and then begin to rise again. It seems to hang around 900 or so but never totally stabilizes. The issue is only at 100 kHz test frequency. At all other test frequencies, the Q displays "0L".
Apparently the actual Q at the lower frequencies is greater than 2000 as that appears to be the upper display limit.

Mica transmitting type capacitors do not suffer from the wandering Q reading. They display 0L at the 100 kHz test frequency. I am testing at 100 kHz since intended use of the polypropylene and micas is for Tesla Coil application which do operate at frequencies in the 200 kHz zone or higher.

The LCR meter offers 100 Hertz and 120 Hertz test frequencies, too. Somewhere I read that the 100 Hertz is for use in Europe where 50 Hertz is standard house service. And the 120 Hertz is for USA where 60 Hertz is standard. I assume I would use the 120 Hertz for a capacitor intended for a 60 Hertz application. But why the doubling of test frequency?

Finally, my DE-5000 LCR meter seems to be sensitive to a slightly weak 9 volt battery. Readings are greater with a fresh battery. And to top it off, readings are different when powered by its 9 volt switching type power supply.

I guess my last question for now concerns “Q” which I understand is the reciprocal of “dissipation factor”. I know that high Q is desirable in capacitors and inductors. But it is a dimensionless number. So what Q should I expect from capacitors? One ceramic capacitor displayed a Q of 80 while the micas apparently have a Q over 2000. Should the ceramic be considered faulty?

I would appreciate any incite to the above to help me understand how to interpret the reading and proper use of the LCR meter.

Thanks,
Ron

[mos6502]

This should answer all of your questions:

http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdf

By the way, it's not 0L, it's OL, meaning overload. The value is simply out of range. In any case, you wouldn't use Q to characterize a capacitor, you'd use D. Q is generally used for inductors.

But why the doubling of test frequency?

If you put a capacitor after a full wave rectifier, it'll see twice the line frequency. But most importantly, capacitor datasheets usually define most parameters at 120Hz (for electrolytics). So that's what you'll use to compare to the datasheet.

Finally, my DE-5000 LCR meter seems to be sensitive to a slightly weak 9 volt battery. Readings are greater with a fresh battery. And to top it off, readings are different when powered by its 9 volt switching type power supply.

What readings? By how much? What does your setup look like? Do you have a precision capacitor/resistor (like 0.1%) to compare against?

So what Q should I expect from capacitors? One ceramic capacitor displayed a Q of 80 while the micas apparently have a Q over 2000. Should the ceramic be considered faulty?

How do you know if a capacitor is good? You have to compare your measurements against the data sheet. Anything else is guesswork.

[4x1md]

Question to DE-5000 users. What exactly is measured in Rs and Rp modes (not ESR/RP in L/C mode) and what are their use cases?

[technogeeky]

Question to DE-5000 users. What exactly is measured in Rs and Rp modes (not ESR/RP in L/C mode) and what are their use cases?

I had this same question for myself a few days ago, so this post made me want to check.


I ran out of time playing around, but I made some observations:

• The actual measurement and acquisition part of the instrument does not change at all (of course). That is: [Ls, Lp], [Cs, Cp], and [Rs,Rp] all look exactly identical under inspection by oscilloscope and FFT. (A sine wave which changes in amplitude depending on the device under test.)
• I'm not sure what it means myself, but I think it's important to clarify you and I both are asking: what is the meaning of the pair [Rs, Rp] when actually testing a resistor?
• I am pretty sure the _series_ and _parallel_ parts of this refer to the effect the device under test would have inserted in series or parallel in a filtering network (like a pi or tee or other kind of filter).
• The amplitude always changes downward (so we are watching the DER EE apply a sine wave, the DUT filters, and the DER EE interprets this filtering action).
• I would guess, having tested some resistors which I guessed would be edge case (9.88M ceramic precision, 0.1 ohm wirewound, 10M wirewound), that what's important is the difference between the values of Rs and Rp. If they are almost exactly the same, then the resistor is behaving very well as a resistor at that frequency (instead of behaving like an inductor or capacitor). If they are very different (try the DE-5000 on 1x oscilloscope probe directly (e.g. no DUT, or the scope probe is the DUT)), then this thing isn't behaving like a resistor at all.
• Note: This method can be used to measure the resistance (really impedance) of a device which isn't actually connected. For instance, try connecting a 1x oscilloscope probe as a DUT (as above), but keep it disconnected from the oscilloscope.
• Note: It seems instructive (but I'm not sure of the meaning) to compare the DCR versus the Rs and Rp of resistors.

[macboy]

DCR is intended to measure resistors, and it works at DC like any multimeter or ohmmeter.
Rs and Rp are part of an AC impedance measurement. The meter measures the impedance by measuring the magnitude and phase of the response of the DUT to a sine wave excitation at the selected frequency. It then fits this response to either a series or parallel model:
- In series mode, the meter models the impedance of the DUT as a resistance (real component) in series with a reactance (imaginary component). That reactance may be inductive (i.e. Ls) or capacitive (i.e. Cs). When set to Rs display mode, the meter displays only the value of the resistance component and ignores the reactive. This can be used to display the ESR of very large capacitors at high frequencies (e.g. for SMPS work) which is not possible in Cs mode.
- Likewise, in parallel mode, the meter models the impedance of the DUT as a resistance (real component) in parallel with a reactance (imaginary component). Rp mode only displays the real component of this impedance.
- other sub-displays are mathematically calculated from the reactance, resistance (Rs or Rp), and frequency.

This is explained, more or less, in the first couple pages of the manual.