1746-NR4 RTD Module

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Drew Harpe

Has anyone ever seen this before? We believe there was multiple spikes between these interruptions. I would like to know how to keep the correct reading after the brown out.
 
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kalpak dabir

> Has anyone ever seen this before? We believe there was multiple spikes between these interruptions. I would like to know how to keep the correct reading after the brown out. > assuming the plc power supply is ok, check the earthing of your system, looks like some cmos component goes into latchup.
 
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Joe Jansen/ENGR/HQ/KEMET/US

Put an industrial UPS on your PLC system aand control power. The food plant I worked at used a small, ruggedized UPS to ride through brown out and spike conditions that were frequent in the spring time. --Joe Jansen
 
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Michael Griffin

We had a somewhat different problem (loss of program), but related to electric power being interrupted to a PLC. One of the electricians noticed that the problem seemed to occur when the electric power went off, and then recovered gradually (over several seconds), or sometimes only dipped briefly. A simple off/wait/on did not cause any problems. Our solution was to install an on-delay relay in the circuit feeding AC power to the PLC's power supply. The relay was set to a 15 or 20 second on-delay - too short to be a significant problem in re-starting the machine but long enough to allow the AC power to stabilise before restoring power to the PLC. We installed this a couple of years ago, and haven't had any problems with this machine since. The relay was inexpensive, easy to install, and unlike a UPS didn't cause any problems with power being present during a lock-out. ********************** Michael Griffin London, Ont. Canada [email protected] **********************
 
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