Distributed control systems (DCS) are designed to be used for a long period of time, 25 years is nothing special. However, at a certain point in its lifespan some important considerations have to made concerning the costs of maintaining the current DCS versus the costs of migrating to a modern DCS. One thing is certain: waiting until a system starts failing is not an option. Everyone, that has a decision-making role concerning distributed control systems, knows that every DCS faces obsolescence after a long and useful life. However, they also realize that migrating to a new DCS requires a considerable investment. The choice to migrate is obviously a very difficult decision. After all: “The current DCS has worked for all these years, why would it stop working anytime soon?”. The answer is relatively simple; when obsolescence makes it hard to work with the current DCS any longer, it is time to consider a DCS migration. Moreover, the growing risk of dangerous failures due to obsolescence makes a DCS migration inevitable.
Why migrate your DCS?
Obsolescence by original equipment manufacturer (OEM)
When spare parts for the current (obsolete) DCS become harder to come by, migration will be a logic consideration. If not because spare parts for a new DCS will be much easier to find, it can be financially justified by the fact that spare parts for the obsolete DCS will become very expensive due to scarcity.
Also, expertise for the current obsolete DCS becomes scarce, while expertise for the new DCS is growing. Throughout the 25 years of functioning well, the DCS was operated by a couple of (expert) engineers. Many of these engineers have retired and took their expertise with them. Newly hired engineers, which are mainly educated in the operation of new DCSs, do often not have the expertise to operate old DCSs. Let alone to recognize necessary maintenance, problems and risks. This would require training of new engineers to operate (soon to become) obsolete DCSs, which is highly inefficient; the obsolete DCS will start failing sooner rather than later. Therefore it is recommended to start the migration process to a new DCS before real problems and risks start to occur.
Lack of production data
A lack or production data might also be a consideration to start the migration process. While your old DCS still provides you with data about the production process, this might be inadequate for nowadays industry. New technologies create many new opportunities. The obsolete DCS has been running for many years without renewal of the technology (hardware). The new DCS with innovative technologies results in better visibility and easier access to plant and production data for better decision making.
Limited network and/or expansion options
Some distributed control systems do not have open communication options. While new control system have real-time information available throughout the enterprise for better decision making. These control systems can be integrated to process networks such as HART, Fieldbus and Profibus. Also, when a plant is expanded and the existing control system is still supported, many companies do not want to install obsolete technology on new process units. Therefore, they will migrate to a new DCS.
Technical end of life
Some distributed control systems have grown obsolete and are showing small failures which might eventually grow into large failures. This causes a growing concern related to the reliability of the (obsolete) DCS. Data often shows the occurrence of failures that do not immediately have an impact, but indicate future reliability issues. Companies endeavor a reliable and stable process and are therefore recommended to start planning a DCS migration as soon as the reliability of the obsolete DCS becomes questionable.
Lack of flexibility and production efficiency
The lack of flexibility and production efficiency of obsolete DCSs has changed to a great extent by introducing scale-able and flexible DCS solutions. “Today’s scale-able and flexible DCS solutions enable process end users to extend their scope at any time from process control and management to include personnel and assets, and to even integrate the resources of their entire business operation” (Honeywell, August 2016).
The afore-mentioned reasons are just a few to take into consideration when thinking of a DCS migration. Once a company recognizes the necessity to migrate the obsolete DCS to a modernized DCS, a financial justification is the next step. How do you justify such a large investment? The following article explains more about: the financial justification of DCS migrations.