Grounds of Power Supplies

[RJHLJH]

Is it true that the DC ground (negative terminal) shares the same ground as all the power supplies that have been wired within same electrical panel?  With this said, can all the negative output terminals be safely wired together.  My issue comes with trying to measure voltages of many power supplies with a cRIO module, namely a NI 9221.  The wiring plan is to wire in the positive side of the power supplies into channels 1- 4 while wiring the negative terminal of each power supply to the same common pin. 

[GerdW]

Hi,

standard AC/DC power supplies use a transformer. After the transformer you have a 'virtual' ground, i.e. floating ground.
You can safely wire several 'floating ground' to one connection without any problems (regarding the DC supplies).

[johnsold]

There is no universal standard. Usually the case you described is valid, but if the person who put your system together needed negative voltages for some reason, positive terminals could be grounded. You should check the schematic diagrams or measure the supplies and connections with voltmeter and ohmeter.

Lynn

[GerdW]

Hi Lynn,

thanks for comments.
After long time working with such hardware I don't use 'positive' and 'negative' connector, I prefer 'ground' and 'voltage' instead 🙂 And normally 'ground' lines can be connected.

Btw. to use an ohmmeter to check a voltage (or current) supply could lead into trouble (and serious damage)...