HP 4261A LCR meter queston, ESR? - Page 1
Forum section: electronics / testgear

author: emptech
author_rank: Regular Contributor
timestamp: November 09, 2017, 08:37:39 pm
content: Back in the day when the HP 4261A LCR meter was designed, I don't think that ESR was something we thought about, so my question, can this model measure ESR? I've been through the user manual, no such term "ESR." But, it does show tests of a series resistance of a capacitor. I don't know if it can read the value directly or does it have to be read via a graph?I have a 4261A but am trying to convince myself to buy a more modern instrument.Jim H.

author: duak
author_rank: Super Contributor
timestamp: November 10, 2017, 01:54:25 am
content: I have an hp 4261A too. It shows the Dissipation Factor (DF) as well as the component's value.If my memory hasn't gone completely blinky, ESR = DF*Xc = DF/(2* ?*f*C) where f is the test frequency & C is the capacitance.I believe the 4261A was designed in the mid 70's and has a state machine to control it. Too bad it didn't have a micro that could conceivably be made to show the actual ESR. I'd almost bet it determines the ESR first and then calculates DF.Cheers,

author: precaud
author_rank: Frequent Contributor
timestamp: November 10, 2017, 02:19:03 am
content: Doesn't it read ESR when you switch from C to R mode? Most of the LCR meters I've used do.

author: duak
author_rank: Super Contributor
timestamp: November 10, 2017, 05:02:10 pm
content: That's a most excellent suggestion Precaud - thx kindly!I just realized the other day that the 4261A uses AC rather than DC to measure resistance so it makes sense that it'll give the ESR directly if set to measure R. Based on a few caps it seems to work just fine.Cheers,

author: precaud
author_rank: Frequent Contributor
timestamp: November 10, 2017, 06:49:28 pm
content: Yeah, just make sure the equivalent circuit is in series mode and that's it.

author: emptech
author_rank: Regular Contributor
timestamp: November 11, 2017, 11:39:28 pm
content: There is a symbol on the front, series resistor and cap. I haven't actually tried that mode, and to test, I guess I'd put a small resistor in series with a capacitor, see if it sees the resistor. The reason I brought all of this up, I obviously have this instrument, and have a simple B&K capacitor meter, but it is the older version that does not measure ESR. Since we are seeing more failures of filter capacitors, sometimes due to high ESR values, I wanted a way to measure them without buying another instrument. So if the 4261A does it, I'm happy.Jim

author: precaud
author_rank: Frequent Contributor
timestamp: November 12, 2017, 05:36:41 pm
content: You can see which equivalent circuit mode the instrument is using by the lit LED next to the symbols in the upper-left corner. Most capacitors are evaluated as series equivalent, so you might not need to change anything. But you can be certain by setting the circuit mode switch to series, and then the R function will definitely give you ESR (the real component), and the reactive component in C (or L) function, at the selected frequency.My Wayne Kerr 4210 is the same way.One other little "gotcha" to be mindful of; most capacitor manufacturers give the ESR spec measured at 100kHz. And dedicated ESR meters read at high freq's too. Your reading at 1kHz will almost always be higher than that, and can't reliably be compared to them.Hope this helps.

author: cnqhdszq
author_rank: Regular Contributor
timestamp: December 10, 2017, 02:31:48 pm
content: I am not professional . but .. I have 5 LCRs They are :TongHui 2820 100Hz/1KHzWayne Kerr 3245 40Hz -300KHzSR715 100Hz 120Hz 1KHz 10KHzWayne Kerr 4225 100Hz/ 1KHz /10KHzand I have ever usedHIOKI 3250 100Hz --100KHzBK precision 886 100Hz 1KHz 10KHz 100KHzso my experience may be useful for you .all the LCR above will show the ESR value when you plug the capacitor in the fixture and turn to R gear .the ESR value is as same as the ESR value showed in the C gear .so I thought the R value of the Capacitor is ESR .