Question on Powering a PLC

[kjmc]

I want to install an Rx3i. Some of the cards require 24VDC power, the relay output, DIs, and Analog Inputs.

There is a 24 VDC input for an external isolated power supply.

I am using the multipurpose P/S modules in parallel, they don't have a 24VDC output so I will have to connect directly to the backplane.


Can I power the P/S modules and the External Supply input from the same DC Power Supply, I realize the potential for voltage drop due to relay coil inrush but I will only energize one at time and the supply is quite robust.

I couldn't find anywhere in the manual where it forbids this, it only mentions "Isolated," isolated from what?

Also, Floating DC power is what is available for DC distribution.

Thanks,

I hope you can help me out.

 

[randylud]

"Isolated 24VDC terminal for I/O modules and a grounding bar that reduces user wiring" This quote from the GE site tells the story. Your question involves asking if you should connect to the backplane. NO! In every PLC system I have ever seen, the I/O modules receive their power from the backplane and I believe you are referring to the power required to operate field devices or loops. This 24VDC terminal is available from the power supply for this system to do just that, although I suspect the loading is a consideration. I would recommend that you provide your own, separate, 24VDC supply to operate the field side of you I/O.