PXI-2575 minimum load

[boit2201]

I work on new project. I will use multimeter PXI-4070 with switch mux PXI-2575. The multimeter will measure voltage on differents tests points of a circuit in test. The input impedance of PXI-4070 are 10Mohms in measure voltage mode. So the current in relays of PXI-2575 will be very low <2.4uA. All voltages to measure are between 0.5VDC et 24VDC. There are also a measure of 8VaC and 16VAC.

The relay minimum load in datasheet of PXI2575 FEV2008 are "10uA at 10uV DC".
The relay minimum load in datasheet of PXI2575 APR2009 are "20mV/1mA".

My questions:

What the minimum load change in 2009 or it's a error in documentation?

What the real signification of "20mV/1mA"?

The current must be always greater than 1mA or periodicly greater than 1mA?

The voltage are voltage to init contact or the voltage must be always greater than 20mV?

What a current less than 1mA decrease life of relay?

If I measure AC voltage what the consequence on the measure when the current are between -1mA and 1mA?

Thank you!

[HeatherBaker]

Hi boit2201,

The February 2008 manual is specifying a minimum current and voltage combination, whereas the February 2009 manual is specifying an either 20mV or 1mA minimum.  This minimum is to ensure the removal of contact buildup that can occur with armature relays.  Ideally the current should be greater than 1mA or the voltage greater than 20mV.  This Developer Zone article explains this phenomenon in more detail.  Measuring an AC voltage should have no effect as long as the minimum current or voltage requirements are met.  Hopefully this helps!