Rigol DL3021 current offset - Page 1
Forum section: electronics / testgear

author: sebastos08
author_rank: Newbie
timestamp: December 22, 2017, 07:22:42 am
content: Hi all,I recently bought a DL3021 Rigol DC electronic load, for tests in low consumption.I also purchased the HIRES-DL3 option to access more accurate display "High Measurement Resolution Option"I have several devices of the brand, and I was confident in this new purchaseAfter a few tries, I immediately noticed something that seemed to me abnormal.In static CC mode, for an I of 10mA of load, my power supply and my dmm displays 20mA of real current. (see photo2)We are here far from the 0.05% + 0.05% FS specification.In my case, we should not exceed 0.010x0.05% + 0.05% x4A = 2mA error.I wanted to investigate the problem by checking that the voltage raised in the DL3021 has no influence in this offset, but in "CC" mode, the voltage has no influence on the regulation of the current I. ( tests done with EXT sense on)I noticed that the DL3021, also sinked 10mA when it was not loading "OFF mode". (see photo1 on my power supply and my dmm)I do not know if there is a relation between this two measurements states and I asked the question to Rigol and I do not have a response from them yet.Is my concern specific to my machine, is it someone who owns this device could tell me if he is experiencing the same problem as me. ?I am for the first time disappointed with the brand and I hope to find a possible way of solution. Otherwise I think I will return the device and turn to another brand ..Case to follow......

author: TurboTom
author_rank: Super Contributor
timestamp: December 22, 2017, 07:07:48 pm
content: Yes it's doing these kind of things... Be sure to check the last two pages of this thread:https://www.eevblog.com/forum/testgear/new-rigol-dc-load-d3000-series/In it's current condition, at least the specimen of the DL3021 I tested was utterly useless for low-current jobs. Check the waveform of the current, it's far from DC. My recommendation would be to return it and get either a Maynuo or an Applent (you even pay a little less for those if you import them from China directly, but they aren't perfect either...though much better than the Rigol).I think as long as these instruments use a single shunt resistor for the full current range, poor performance at the low current end is no surprise at all. Especially Rigol uses a very low shunt (0.5mOhm -- Applent and probably also Maynuo have a total shunt resistance in the ballpark of 15mOhm).Good luck,Thomas

author: sebastos08
author_rank: Newbie
timestamp: December 23, 2017, 01:25:41 pm
content: Thanks a lot Thomas for this reply.i didn't see the interresting topic that you linked in the previous post before.it's really very interesting all the analyzes and measurements that you have done.but I don't understand that when the machine is OFF, the shunt resistor must not sink any current.why did I have 10mA on my machine. it seems to me huge and completly out of Rigol specs .. you spoke by your side of 3 to 5mA, is that it?I especially suspect that there were no calibrations that were done on my machine.Sebastien

author: sebastos08
author_rank: Newbie
timestamp: December 23, 2017, 05:13:59 pm
content: Quote from: atx on October 22, 2017, 07:36:28 pminteresting feedback too.i haven't made this range tests between 0-10mA. i'll do it next week.As Thomas said above or in another subject, I think this DL3021 is not made for its low current values.I'm moving more and more towards the idea of an exchange with a MAYNUO M9711 or 9712This product don't seems to be ready for the public.it's a shame because I like its screen and the adjustment interface it offers

author: joad
author_rank: Newbie
timestamp: May 20, 2018, 12:35:03 pm
content: Hi, I have a DL3021 and mine has a 10mA offset like @sebastos08.Any news about this? Or is it possible to calibrate the DL3021 on my own?Sorry to bump this one, if there is any news about this elsewhere?

author: sebastos08
author_rank: Newbie
timestamp: May 21, 2018, 10:16:38 am
content: Quote from: joad on May 20, 2018, 12:35:03 pmdepending on my 10mA offset value, i’ve sent my unit to Rigol . They are corrected and solve the issue, and upgraded the fw. now the unit work fine like the announced specsi’ve no details on their mod, but it’s seems that the first batch design wasn’t totally finish and checked deeply before the launch of the product.