Don’t Set and Forget: Control Systems need Preventive Maintenance too!

Maintenance is a critical in an industrial setting. While in a water system this may include routine tasks such as recalibrating transmitters, cleaning reservoirs, and replacing filters, on the control system side there are often a lot of maintenance items overlooked or forgotten. In the past, when control panels were full of relays or single loop controllers, maintenance would primarily occur on the electrical side e.g., tightening terminal screws and testing contactors. However, now that control systems have become advanced as part of Industry 4.0, there are a number of additional steps needed to keep the assets efficient & operational. This article focuses on these steps, as new technological advancements require further maintenance measures.

Maintenance can be broken down into Reactive and Preventive. Reactive maintenance is when we are repairing a component as a response to a break/fix incident. Preventive maintenance occurs proactively before a component needs a repair, and is a great way to monitor its state, prolong the equipment life, and reduce unexpected downtime.

Within control systems, Reactive maintenance is often in the form of troubleshooting after a problem has already occurred. E.g., we may need to go through a PLC program to find out why a motor isn’t starting and work with an electrician to determine and fix the problem, or, in another case, to find out why a reservoir is reading full when it is really drained. These efforts may involve tracing a 4-20mA loop and testing the sensor, and consequently restoring a program to a previous state, replacing fuses, or checking breakers. Each support ticket like these ones is unique as well as its resolution steps. The impact of reactive maintenance will vary from facility to facility, and depending on the control system this could result in low water levels in a municipal system or potential loss of revenue.

While reactive maintenance is often inevitable, we encourage preventative maintenance to be completed whenever possible to take a more proactive approach. This will ensure the maintenance team is taking reasonable action to minimize breakdowns or other unplanned electrical or software issues. Overtime, electrical equipment can experience wear and tear; contactors can fail; terminal screws can loosen resulting in poor connections; float switches can get stuck. Even in a PLC/SCADA, time can have detrimental effects; firmware can become outdated and unpatched vulnerabilities may leave your control system exposed. Backups can become obsolete if not updated or lost as the facility transitions between various staff and contractors. Such incidents are detectable and can be addressed with adequate planning.

Some benefits of Preventive maintenance in a control/electrical system are:

  • Equipment inspections and repairs ensure sustained compliance with the Canadian Electrical Code or equivalent within your jurisdiction
  • Visual wiring inspections, and tightening terminals in all electrical panels (control panels, starter panels, MCCs, etc.), leading to less nuisance trips or equipment failure
  • Instrumentation and safety device verification (including associated alarms) that re-confirms accuracy and calibration. This also includes:
    • Clean sensors where applicable
    • Verification of level floats functionality
    • Starter contact inspection and replacement as necessary
  • Regular backups of PLC, HMI and SCADA as well as when modifications are made (can be manual or automated) so that Disaster recovery is possible and timely. Also,
    • Periodic Functionality testing of alarm notification systems
    • Updates of the operating system on SCADA computers or servers
    • Backup of SCADA historical data and verification of all backups’ integrity
  • Update and document firmware on control system hardware such as PLCs, HMIs, VFDs, routers, switches, and radios that minimizes vulnerabilities and reduces risk
  • Review and optimize alarms and their notification method to prevent alert fatigue
  • Keeping up-to-date documentation so that troubleshooting is quicker
    • Network layout, and network configuration
    • Electrical drawings and documentation

These examples are indicative, and the exact tasks performed should be customized to meet the specific needs of your facilities. The recommended frequency of each maintenance task will also vary from site to site and from client to client depending on their goals, risk tolerance, and the impact of down time. Maintenance items could be completed by trained staff or qualified support providers.

To minimize unexpected downtime, it is important for facilities to plan and budget for control system maintenance. By performing preventative maintenance on your system, you can reduce large, unexpected costs and potentially overall operating expenditures. If you are looking for assistance in preparing a maintenance plan or performing control systems maintenance, give ICI a call at 250-372-1486 or send us a message at

-Jason Marchese, P.Eng, PMP