02-20-2019 09:01 AM
Note: Duplicate of https://community.keysight.com/message/91866
What are the negative fluctuations that we expect with preferably the 34410A (or the 34401A) when we are in an open circuit or when a device is turned off for DC&AC Voltage&Current measurements?
I want to avoid the -0 issues with automated measurements, however I need to have a valid reason to put a negative value as a low limit.
Measurement | Range | Accuracy | Math | Tolerance |
---|---|---|---|---|
DC Voltage | 100mV | 0.0050+0.0035 | 0.000035*0.1mV | 3.5 uV |
AC Voltage |
100mVrms | 0.5+0.03 | 0.0003*0.1mV | 30 uVrms |
DC Current | 100uA | 0.05+0.025 | 0.00025*100uA | 0.025 uA?? |
AC Current | 100uArms | 0.1+0.04 | 0.04*100uA | 0.04 uA?? |
If I consider full range for reading:
Measurement | Range | Accuracy | Math | Tolerance |
---|---|---|---|---|
DC Voltage | 100mV | 0.0050+0.0035 | 0.000085*0.1mV | 8.5 uV |
AC Voltage |
100mVrms | 0.5+0.03 | 0.0053*0.1mV | 0.530 mVrms |
DC Current | 100uA | 0.05+0.025 | 0.00075*100uA | 0.075 uA |
AC Current | 100uArms | 0.1+0.04 | 0.14*100uA | 0.14 uA |
Can anyone confirm or correct? Especially for AC since the specs are for at least 0.3% of range and a frequency over 3Hz.
Thanks
02-21-2019 09:09 AM
As this is a Keysight device, it's not something we can answer spec questions about and guarantee we'll be correct. Please rely on the Keysight forum for an answer to this question.
02-21-2019 01:59 PM
Your question isn't very clear. What do you mean by "negative fluctuations", "-0 issues" and negative value as low limit?
The DMM can measure both positive and negative voltage and current so the specs posted are most likely absolute values.
Elaborate on what you want to know, or describe what you are seeing and perhaps I can offer a few comments as I use a 34401a quite often. (Mainly in DCV and DCI modes.)
Craig
02-28-2019 11:17 AM
Hi Craig,
Sometimes when no voltage or current is measured with the DMM it will return a very small negative value such as -0.000001A.
Try powering ON your DMM and ready the voltage with without connecting the leads (same as reading an open circuit) and you should be getting some negative values (even if you ground the low side probe).
03-01-2019 12:21 PM
That becomes an accuracy issue of the instrument. If you have ever dealt with an ADC then you would know all about INL & DNL. The instrument should provide sufficient information in order to make a determination on how LSB's of accuracy then based upon the range chosen you can select your negative low side value.
03-04-2019 08:51 AM
That gives some extra information to dig through specs. I remember using the INL/DNL for NI DAQ cards for tolerance calculations in the past. Although Agilent didn't provide that information 😛
From the specs I found extra information that I think I can add:
A-to-D Converter Noise Performance: @30ppm of range
DC Voltage Linearity: 0.0002% Reading + 0.0001% Range