By Bob A.
Occasionally over a six-month period, we had reboots with our rolling mill control system that caused production headaches but the crews learned to clean up the mess and proceed. Then, suddenly the problem got worse, occurring multiple times a day. So now, it was a dedicated priority to find out what was going on.
So first thing in the morning, we are all gathered up to examine the entire control system. Right off the bat, at a time when the crew is typically planning out the day’s work, it happens. After that, nothing. Late in the day, as we were cleaning up all the electronic monitoring equipment, it happened again, but no one was watching. This went on for several days until about the third day, when the foreman observed that it happened every morning when he brought out the schedule. We were all scratching our heads.
Later that day, as I’m leaned over the new schedule printer and peered into the control panel, I noticed that the big outlet down below for the printer, was not being used. So I traced out the line cord for the printer and discovered that it was plugged into a strip that had previously be used for a small desktop line printer years before. Every time this huge printer/copier was used, it would warm up and overload the isolation transformer for the control system. Upon checking, we found that there had been a smaller one there for a few months, but it was needed somewhere else, so the larger one was placed here. The smaller one only occasionally caused the problem where as the larger one always caused the problem.
As a courtesy, the cold mill superintendent sent a bill to the IT department for all the lost production. After that, all plant IT activity was scheduled through the operations automation personnel.