Applications
Strategies for modernizing and optimizing legacy DCSs
SOURCE: ROCKWELL AUTOMATION
Plants with an aging DCS will require an upgrade to a modern automation system at some point. Selecting the right upgrade strategies and the right project management team are critical to success. A third-party service provider can often assist in project management and the development of the upgrade strategies.
A modern automation system provides tight integration among various controllers and computing systems, allowing for integrated monitoring and control of the entire plant. MANY INDUSTRIAL MANUFACTURERS TODAY have aging distributed control systems (DCS) in place. These legacy systems may work fine, yet as time goes on, there is increased potential for exposure to risks, which may prevent them from capitalizing on productivity benefits from state-of-the-art technologies. As a DCS reaches the end of its useful life, modernizing to a new automation system is essential. Once the decision to modernize DCS systems has been made, there are four main strategic decisions that need to be considered: • Replication vs. Innovation • Horizontal Approach vs. Vertical Approach • Rip and Replace vs. Phased Migration • Hot Cutover vs. Cold Cutover If you or your operation are considering converting an existing DCS to a new
48
automation system, learn how each of these decisions can impact your overall strategy, minimize cost and reduce potential risk.
Decision 1: Replication vs. Innovation
One of the key decisions to make when modernizing a legacy DCS is determining whether it should be merely replicated or enhanced by implementing a more innovative, modern DCS system. Replication is a replacement of existing automation hardware with new components, keeping all functionality identical to the greatest extent possible. The main benefit of replication is that the new automation system components will be supported by the supplier for decades — particularly important when the DCS is reaching the end of its useful life. Some improvement is typically realized, as the new
controllers often have superior algorithms for loop control, and new hardware brings more memory and CPU power, so some consolidation is possible. However, any existing HMI-related problems with poor process adjustments, alarm handling, and identification/resolution of issues will still exist. I/O may be replaced one for one, with no upgrade to distributed I/O via digital networks. Changes are only made to I/O to resolve any compatibility issues among I/O and field devices. Conversely, innovation means improving the existing system to perform optimally with a new automation system. These improvements may lead to increased production and throughput, quality of product and increased safety performance. New controller configuration and code can be developed to automate existing manual
in d u s t r ial et h er ne t b o o k
09.2021
