PLC2 Rack

Hi ,

We have a AB PLC2 rack where we have replaced the processor with a RIO adaptor and this has worked fine for years, just this week however the power supply on this rack has started shutting down at random times and the only way to get it going is to remove and replace it's fuse (simply switching it off and on doesn't work) we have tried replacing the power supply but have the same problem, even when all the IO and the RIO card were removed it still happens. Has any one any ideas it's looking like the rack or connecting cable between the rack and PSU.

Thanks

I do not know what the heck is happening to your system Jezz, this indeed sounds strange. However, if you turn the switch off or remove the fuse, this is the same thing other than the time element. I am sure the supply is off longer when you remove the fuse and put it back in. But I do not think this is related to your problem.
As you state, the same thing occurs with a different supply, with the I/O and comms cards removed from the rack so that only leaves cables and the rack itself. I have never had a rack fail in over 25 years but it is possible or if it has sustained some kind of damage or has accumulated dampness or corrosion. It may be necessary to change the rack to rid yourself of this problem.

On the other hand I've seen far more 1771 rack failures than I've seen power supply failures. So that being said I would next try another rack.