DER DE-5000 LCR Meter showing incorrect values - Page 1
Forum section: electronics / testgear

author: ironsniper1
author_rank: Regular Contributor
timestamp: April 20, 2019, 06:00:58 am
content: hey everyone first time poster and hopefully long time learner from everyone here! a day or so ago my lcr meter was showing the correct cap values etc but now for some reason it will show a 470uf cap as 428uf and i am not sure why, i have calibrated it several times but so far no dice, does anyone know what i could do to try and fix this? also these caps are brand new never used

author: maginnovision
author_rank: Super Contributor
timestamp: April 20, 2019, 06:05:08 am
content: What's the tolerances of the caps?

author: helius
author_rank: Super Contributor
timestamp: April 20, 2019, 06:39:04 am
content: 428 uF for a specified 470 uF is a deviation of 8.9%, well within the typical ±20% for electrolytic caps and also within the tighter ±10% tolerance that is offered for the better ones.

author: ironsniper1
author_rank: Regular Contributor
timestamp: April 20, 2019, 06:45:04 am
content: so something like that should be normal then? i hope so cause was reading them at about 450uf before so i am not sure why its showing lower now

author: TurboTom
author_rank: Super Contributor
timestamp: April 20, 2019, 06:54:17 am
content: Hi Ironsniper, welcome to the forum! A dedicated LCR meter (I haven't got the DER5000 but an Applent AT826, yet for practical applications they should be comparable) offers many parameters that may actually affect the measurement results. First of all, it's always a good idea to use kelvin (four-wire) probes to measure the voltage directly at the terminals of the DUT and eliminate the resitance of the probes/connections themselves. Moreover, the measurement frequency has a major effect on the results. Especially electrolytics will show a considerable dependency while small plastic foil (particularly polypropylene/polystyrene) caps are almost independant. In case of the electrolytic caps, the temperature of the DUT also may have considerable effect, though this affects more the ESR than capacity. Electrolytics are usually specified at 120Hz measurement frequency, so please make sure you select something in this range.Cheers,Thomas

author: ironsniper1
author_rank: Regular Contributor
timestamp: April 20, 2019, 06:58:46 am
content: Quote from: TurboTom on April 20, 2019, 06:54:17 amjust checked the frequency and it was not set correctly, i changed it to 120hz and now its reading like it should and my kelvin clip upgrade is working perfectly! thanks everyone!

author: cvanc
author_rank: Frequent Contributor
timestamp: April 20, 2019, 12:55:49 pm
content: Quote from: ironsniper1 on April 20, 2019, 06:58:46 amYes, electrolytic capacitors often read VERY differently when tested at different frequencies. The displayed value goes up as you raise the test frequency.Enjoy the 5000; it's a useful tool.

author: TurboTom
author_rank: Super Contributor
timestamp: April 20, 2019, 07:49:42 pm
content: Quote from: cvanc on April 20, 2019, 12:55:49 pmReally? I always found it to be the other way round, i.e. the higher the test frequency, the lower the measured capacitance will be. This also makes more sense from a theoretical point of view: Since some of the (AC) current flowing though an electrolytic capacitor is in forms of ion current, i.e. the physical movement of atoms (dissolved in the electrolyte), there will be some kind of "inertia" to put it simple and better imaginable. And this ion current won't follow the high frequency as easily as it will lower frequencies, hence the lower capacitance.Cheers,Thomas

author: flash2b
author_rank: Regular Contributor
timestamp: April 20, 2019, 07:57:31 pm
content: Same here, go higher in measurement frequency results in a lower capacitance.Capacitor Nippon Chemicon SXE 100uF 35V test on a ZXP ZX8511D with OPEN/SHORT calibration before the measurement:On 100HzOn 120HzOn 1KHzOn 10KHzPlease note that the ESR on 120Hz is the highest and that is is much lower on higher frequenciies.

author: shteii01
author_rank: Frequent Contributor
timestamp: April 20, 2019, 09:30:42 pm
content: Step 1. Get capacitor datasheet.Step 2. Read capacitor datasheet.

author: BravoV
author_rank: Super Contributor
timestamp: April 21, 2019, 02:43:48 am
content: Quote from: shteii01 on April 20, 2019, 09:30:42 pmStep 3. Measure with the signal's specification "according" to the datasheet.