# AC Ripple in PLC



## JRaef (Mar 23, 2009)

Oops, right answer to the wrong (similar) question, sorry if you saw the previous posting.

AC ripple? What do you mean by that? Are you seeing an AC ripple in your DC power rail to the processor? that can be EMI or RFI from improper grounding.


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## hascontrols (Jul 15, 2013)

JRaef said:


> Oops, right answer to the wrong (similar) question, sorry if you saw the previous posting.
> 
> AC ripple? What do you mean by that? Are you seeing an AC ripple in your DC power rail to the processor? that can be EMI or RFI from improper grounding.


I haven't been to site yet to troubleshoot issue. It's a fly in site that's in a remote area. I'm suspecting there is issues with the grounding. How would I go about testing for EMI or RFI from improper grounding?
I will be flying into site tomorrow


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## xlink (Mar 12, 2012)

A harmonics analyzer for the lines if you or the neighbour have drives.


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## RIVETER (Sep 26, 2009)

hascontrols said:


> Im new to the troubleshooting of PLCs but here is my issue. I have a GE Fanuc PLC that keeps losing its processor. I haven't troubleshooted this issue yet but im suspecting Power or grounding issues.
> My question is, What are some ways of checking for AC ripple in the power and grounding system. Any other helpful ideas would be great......
> Thanks


Are there any problems with the utilization devices in the system such as...a valve that will sometimes shift, or not shift when called for or a prox switch that flickers?


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## IslandWire (Aug 3, 2013)

*ID an AC Ripple*

Try a handheld oscilliscope like a Fluke 123. Connect channel A to your DC power supply or to the input/output you are having trouble with. By adjusting the settings on the scope, you will be able to see anything other than pure DC that is in that circuit. By checking voltage level and frequency and watching the waveform, you should be able to figure out where the interference is coming from.


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