keithley 2000 (2015) ac current problem - Page 1
Forum section: electronics / testgear

author: linux-works
author_rank: Super Contributor
timestamp: January 24, 2014, 01:23:33 am
content: I bought a 2015 locally and am testing it out now.all the ranges seem ok except I have a question about ac current. I bought the DMMcheck device (voltagestandard.com) and I'm using the ac current (1ma) test on the keithley but I'm not seeing a reliable 1ma. sometimes I see nothing (same as leads left unconnected) and only when I cycle thru the range (to 1A range) do I see something that looks close to 1ma.on the dc-i range, things are fine; I see 1.000something mA on dc-i. but on ac-i, it looks like there is only the 1A and 3A ranges and so I won't see a 1.something reading, but a 0.001something reading. is that correct?the fuse on the amp terminal is fine (esp since dc-i works just great).I have some time to eval this meter before returning it or keeping it. overall, it seems nice but I'm concerned that ac-i is not right.fwiw, when I check the ac-i on my fluke 45, it checks out very very close to 1mA so I'm pretty sure my brand new dmmcheck device is working ok.

author: linux-works
author_rank: Super Contributor
timestamp: January 24, 2014, 03:19:53 am
content: btw, here's a photo of the dmm check device on the keithley, showing pretty close to 5v

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 24, 2014, 03:28:05 am
content: I have the exact same question with a used 2000 I have! Everything seems fine except ACI. I am having a hard time finding a calibration lab locally that could calibrate this thing...

author: ckm
author_rank: Contributor
timestamp: April 29, 2014, 07:01:15 pm
content: I have a 2015 and a DMMcheck as well. Everything is within 0.02% other than AC current, which is 10% out.This would seem to be out of spec:Code:ACCURACY1: ±(% of reading + % of range), 23°C ±5 °CCURRENT CALIBRATION3 Hz-10 Hz | 10 Hz–3 kHz | 3 kHz-5 kHz-------------------------------+---------------+----------------1.000000 A-1 ?A 0.30 + 0.04 | 0.10 + 0.04 | 0.14 + 0.043.00000 A-10 ?A 0.35 + 0.06 | 0.15 + 0.06 | 0.18 + 0.06That said, it may be something to do with DMMcheck or it could also be a function of the probes/leads. I've had issues with AC current & DMMcheck with other meters.Although it's unrelated and not in the same class, I noticed on my Uni-T U71D that in the specs, the mA range only goes to 400mA, then the 1A range takes over. Which means there is a hole between 400mA and 1A where nothing is measured. Perhaps the same thing is true with Keithley or there is a lack of accuracy in that range (e.g. it can't do sub .5A accurately), I haven't looked at the manual closely enough. What's clear is that if you want to measure things in the mA AC range, a 2015 is not the meter to get....I'm not personally inclined to test any further since I have a Fluke 189 which is within 0.5% on AC current, but it is interesting that 3 different meters have the same issue. Amazingly, the Fluke is with 0.09% overall, which is really very, very good for a 10+ year old handheld.... No wonder they retain their value.P.S. Attached is my test report. I do this for all my gear so I know what is most accurate....

author: quarks
author_rank: Frequent Contributor
timestamp: April 29, 2014, 07:41:36 pm
content: The 2015 does not offer low ACI ranges, therefore 1mA in the 1A range is only 0.1% of the range and that is just to low to measure accuratly.

author: KJDS
author_rank: Super Contributor
timestamp: April 29, 2014, 07:43:11 pm
content: Here's a video showing the effect.