Recently we had a call from a plant operator who was flummoxed by a plant stoppage. The programme had been running for 20 years and suddenly it wasn’t working, a local electrician was called in who then replaced every component in the Programmable Logic Controller (PLC) box. The plant was stopped for 2 days, costing money and pushing back projects.
The electrician then called us at N2P; after chatting through what was happening, we directed the electrician to check the lights on the PLC; sure enough, one was flashing – the plant start light. Going to the manual and checking the information for that light revealed that the problem was that someone had hit the Emergency Stop button.
A further chat revealed that an external E-Stop on the outside of the plant had been accidentally hit by a painting crew that had been on site.
Be sure to check all lights and error codes in the manual, then think about context. What has happened out of the ordinary between the plant working and stopping?
- Check The Whole Line
Everything in your plant is connected, so if one component is not functioning, try to isolate the issue by checking everything on the line; figuring out what IS working creates a process of elimination that will eventually lead you to the fault.
A customer recently got in touch because the Bitumen Pump in their plant had stopped operating. We discovered there were no error codes present and no alarms or lights signaling a direct fix. Once this was ruled out, we had the operator check the PLC to see if the output was turning on. This led us to rule out a fault in the software and to enquire as to whether the relay that enables the drive was operating correctly – we discovered that the relay was not turning on.
At this point, we knew what was working and what was not working; we had the operator call in an electrician who checked the wiring, ruling out an electrical issue. The next port of call was to check the bitumen tank levels; it was discovered that the tank was at high level, and this is what was shutting the pumps down.
Through a process of elimination, the problem was isolated and solved – educating the operator on what may work to fix such a problem if it occurred again.
The issue may not be with the component that is not working; start with checking error codes and work your way through all the other components that are connected to the part of your plant that has stopped operating.
Before You Call For Help
- Note what IS working, is the issue localised to a single motor, pump, drum or belt? Or is the problem widespread?
- Check if you are receiving an error code. Is there an alarm? Flashing lights? Check the whole screen for directions to faults, overloads, low air pressure etc. – take notes and a photo, and be sure to take another after you have tried a fix.
- Check whether your scheduled maintenance is up to date. Could you have a component that should have been checked or replaced?
N2P are always happy to help, so check your error codes, make your notes and call us if you still need assistance.