09-23-2020 09:52 PM - edited 09-23-2020 09:53 PM
We have been using NI PXI DMMs for some time to measure small resistance values (typically under 30ohms). We of course use 4-wire measurements to eliminate lead resistance and we also ensure that the lead resistance is less than the specified 10% of the range.
When looking at the latest NI-DMM manual (http://zone.ni.com/reference/en-XX/help/370384V-01/dmm/4-wire/ ) I noticed that it indicates that if the Maximum 4-wire lead resistance is exceeded (10% of range) there is a potential of damage to the DMM (specifically the current source used to provide the 1mA test current in our scenario). While it is clear that the voltage drop over the test leads would cause a problem, it raises a few other questions.
I have asked these questions through the appropriate channels but am interested to see if anyone in the community could help shed some light on this.
Thanks in advance.