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Pressure Switch Test in COMPASS for Pressure

Below are screenshots of a Pressure Switch DUT setup, and an associated test that uses an automated pressure controller. It would also work manually if you can can control the pressure precisely.

The pressure switch has a voltage output that nominally switches from 0 to 24 V around 10 psi when the pressure is increasing, and switches from 24 to 0 V around 9 psi when the pressure is decreasing. The voltage output is read by a DMM (Other Device) that is setup separately as a Support Device in COMPASS for Pressure. 

The final output is just setup as 100 psi although we're not going to show the corresponding DUT pressure on the report, just the reference pressure and the DUT voltage. You can use this DUT setup for any 0-24V pressure switch DUT and just consider the 100 psi as 100% instead of 100 psi during the setup, and when the test is running if you show DUT pressure on the screen.

Setup the Test points for the resolution required for good readings of the switch point of the DUT. For this example it is setup for 0.25 psi increments.

Note that there are 3 pressure cycles for repeatability testing. A long enough Dwell time worked better than trying to set appropriate Hold or Stability limits in COMPASS. They are just set to zero to leave the pressure controller settings as is, or to ignore them. The Ready/Hold Time is set to zero because the pressure switch will change state during the Dwell time.

Here is a plot that is shown during the test, and on the Calibration Report. It clearly shows what pressure the switch is activating at.

Another method would be to set a pressure and then abort pressure control when the switch activates. You have to be able to increase or decrease the pressure quite slowly for this method to work well. If you have an automated pressure controller, and are familiar with setting up macros,  here is the article:
Macros: Pressure Switch macro to Abort Pressure Control When Switch Activates

If you have questions contact Fluke Calibration Pressure Technical Support at the below link or by calling +1.877.355.3225

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