What are the most important considerations for DCS maintenance and repair?

Visual inspections are, in my opinion, the most important for good DCS maintenance. Starting from the fact that each system has a Monitoring System with which you can see the "health" of the DCS and take action as soon as possible, knowing how critical the DCS are for the plant. In addition to routine walks through the different systems, servers, remote I/O cabinets, etc. After the visual inspection, record these anomalies for analysis, repair and follow-up.

System and Hardware Alarms are the point to check to DCS health including Diagnotics. Visual inspection may include: - Processor, IO card Indicators - Power Supply Health - Temperature - Dust, Moisture Traces if any - Loose wiring - Fan, Filter Check etc.

Well, Preventive maintenance is very important to increase life of DCS as well as avoid unexpected failure and plant shutdown. But I would also highlight the ignored thing that is availability of spares. Better to calculate risk and do PM if there are spares available.

Always remember, golden rule for DCS maintenance: take backups before and after modification. Now, follow checklists and SOPs to perform planned Preventive Maintenance. I have shared many DCS checklists on profile for free.

I would make it easier by describing into DCS KPIs for example: - 100% PM done on time as planned - 20% Spares are available - 0 Corrective or Breakdown maintenance - 0 Failure or no downtime - Alarms are within Operator Manageable range that is defined by ISA 18.2 and IEC 62682

Being senior DCS Engineer, I would advise below 5 points for DCS proactive maintenance activities following a proactive maintenance and repair strategy: 1- Perform regular system checks and inspections to identify potential problems early on. 2- Schedule preventative maintenance tasks to address known wear and tear issues. 3- Implement a regular software update and patching schedule to address vulnerabilities and improve system performance. 4- Maintain regular system backups and implement a disaster recovery plan to ensure quick recovery in case of failures. 5- Provide cybersecurity training and awareness programs for personnel to identify and prevent cyberattacks.

Most DCS systems have too many alarms or outdated alarming. If your system operator is clearing alarms constantly and those alatms, compared to log data, are inaccurate, or over sensitive, then analysis should be done with the operations personnel to understand why. Because DCS programs are constantlybchanging, keeping alatming up to date is difficult. Its also tedious so it geta put off, and people work around issues by running in manual. However, if you want to know the state of your system, sit with the operator and listen.

1)Check incoming power supply quality. Spikes from switching power supplies can blow capacitors and other sensitive components. 2) Monitor cabinet heating amd ventins systems including filters. 3) check above the cabinets for iron filings from installation. When electricians drill holes to install cables, they don't often cleanup properly and those iron filings can find their way into backplanes and circuit boards. 4) keep a can of magic smoke around so you can put some of it back after something goes wrong and that magic smoke leaked out!