For many process plants it is inevitable to recognize the need of migrating an old distributed control system (DCS) to a new control system. The decision-making for the migration process is dependent of many factors, including the financial justification to the people that own the company purse. They need to see a return of investment (ROI) before they make the decision to invest in the migration to a new DCS. In order to do this, a comparison needs to be made between the cost of continuing with the current (old) DCS and migrating to a new DCS. Many factors are crucial determinants in this financial analysis and together they are forming the total cost of ownership (TCO).
Both for the current DCS and the new DCS the TCO needs to be determined. The expected expenses for the new DCS need to include several factors. A table presented in an article from Rockwell Automation shows the different factors that form the TCO.
TCO components
| Purchase price |
| Cost to integrate into balance of plant |
| Training |
| Required maintenance |
| Spare parts acquisition and stocking |
| Downtime |
| Changeover time |
| Off spec product due to quality issues |
| Energy to run the system |
| Throughput less than optimal |
| Cyber security compliance |
| Integration to other plant automation/information systems |
| Long term support |
Another table presented in the same article from Rockwell Automation shows the benefits of migrating to a new distributed control system.
Benefits of migrating to a new DCS
| Reduced maintenance |
| Less downtime |
| Enhanced data collection and analysis capabilities |
| Ability to integrate other control/information systems |
| Quicker product changeovers |
| Fewer manual operations required |
| Improved quality |
| Less energy required |
| Increased throughput |
| Advanced process control capability |
| Built-in cyber security features |
Comparing both tables gives you an idea of the factors that influence the decision to either start migrating to a new DCS or keeping the old DCS. This article is based on the original article by Rockwell Automation, which you can find here: http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/proces-wp005_-en-p.pdf
