High current resistance measurement

[PEng]

We need to preform resistance measurement with 4 wire (high accuracy) but the current specifications are 100mA for most of the channels and 1A for some and 10A for others. So we can't use the 4 wire connection provided with NI 4060 or 4070. Have you some hints to give us? (We are thinking about measuring voltage and current but we need to do syncronously [two DMM] or it could be sufficient to switch between measurement mode [one DMM]?)

Thank you in advance for your reply.
Luigi Magni

[Jack_A.]

The NI-4060 and 4070 provide the test current to the circuit when performing a resistance measurement. For example, the 4070 will output a test current of 100uA for a resistance measurement range of 10kOhms. This is all listed in the specifications for both boards.

So, does your device need some kind of excitation? Do you have current going through your device during the measurement time? Are you providing these current values or are you expecting them from the 4060/70?

Jack Arnold
Application Engineer
National Instruments

[PEng]

We are facing with various kind of applications in which an accurate resistance measurement is required. From quality testing of sliding contacts to resistance measurement of windings on large power transformers.
In these applications large currents are requested instead of the very low 100uA that the NI-4070 provide (we don't expect high current from the DMM of course).
So we are trying to arrange circuits with an external controlled power supply (DC current) and measure voltage and current with a very accurate DMM.
The problem arise because the voltage and current measurement aren't syncronous (in order to make the measure we need a current going through the device) using only one DMM (otherwise it is possible to make syncronous measurement).

Luigi Mag
ni
System Engineer
Pragma Engineering (Italy) AM