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.
> 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.
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
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] **********************