DCS Upgrade Detailed

FROM THE OCTOBER ISSUE: Distributed control systems continuously evolve. Trident Automation has tips for staying current and efficient.
By Jason Hurst | September 04, 2018

The distributed control system (DCS) is the brain of any manufacturing plant, providing the intricate knowledge and responsiveness needed to keep production running smoothly. For many plants, the decision to upgrade a DCS is often made well beyond the life of the system, when operations are starting to fail or falling behind current technology.

So how do plant managers know when it’s time to upgrade? Here are some key points to consider.

Success with Partners: The best DCS upgrades are done through planning ahead with both the manufacturer and a solution partner—an integrator with a long-standing relationship with manufacturers, in product availability and the latest technology. Knowing the direction a DCS manufacturer is moving and the technology it provides is critical. It’s not wise to invest in a control system manufacturer that has no long-term strategy. It’s important to build a relationship with the manufacturer to know its long-term product strategy and how it plans to get the most updated hardware and software for a facility. Try to stay ahead of obsolescence and systems that have high cost of ownership. 

Solution partners typically have lower overhead than the manufacturer and will offer options in product integration rather than representing only one product line.

Security Concerns: Viruses and ransomware have become a real concern for every business. Having a secure network, anti-virus servers, latest security patches and flash-able DCS hardware can secure plant operations. Many manufacturers offer software subscription services for annual fees that keep systems secure with updated software patches. Plant managers might be tempted to avoid these fees, but they could be the difference between secure systems and hackable software.

New Technology: Newer doesn’t always mean better, but in control system technology, even a few years of innovation can provide enhancements and improvements for plant operation. Most manufacturers now include multivariable predictive control (MPC) and advanced regulatory control (ARC) as part of the controllers. The human-machine interface (HMI) will allow team members to visualize sequences and interlocks right on the operators’ screens. Often, several old controllers might be replaced with one new, more powerful controller. Having an OPC-compliant system allows for flexible interfacing to any third-party data analysis package and historian servers. It is now easier than ever to have a read-only web interface view of process graphics available anywhere online.

Cost and Maintenance: As a DCS matures or is slated for obsolescence, cost for those products tends to rise at an alarming rate. Delaying an upgrade can lead to increases in both cost and deliverability of a product. With an outdated DCS, downtime is further complicated by waiting for replacement parts that might no longer be available through the manufacturer. Finding parts from third parties is challenging and the reliability of the parts is often questionable.

Obsolescence of Current DCS: If a plant’s operating system is obsolete, what are the next steps? First, don’t panic. Chances are the current vendor has a product solution or competitors have a product strategy to upgrade an old system. Start asking questions of vendors or a solution partner, but make sure the current system is factually represented, and itemize performance issues. The more information provided up front, the better manufacturers and integrators can help design a DCS strategy for a specific plant.

Approach Options
Two common approaches exist for upgrading a DCS:

• Phased-in

The phased approach spreads the upgrade out over several years. The first step is usually the HMI. The servers and operator interface are changed, leaving the main control system and inputs and outputs in place.  Later, the controllers and inputs and outputs are replaced, resulting in an entirely new system.

Advantages include lower process interruption risk, cost spread out over time and less interruption for operators. Disadvantages include delayed implementation of control technology, as well as 10 to 20 percent higher cost than a full DCS replacement because of multiple visits to a facility and possible manufacturing price increases.

• Full Replacement

A full DCS replacement involves shutting off the current system and replacing it with a new one. This method requires extensive planning. In most cases, plants experience several days of downtime to make the full transition, followed by several days of onsite training for operators.

Advantages include reduced cost, full access to the most updated technology and a robust, new platform. Disadvantages include operational disruption, and new vendor and integrator relationships.
Most important in a DCS replacement is to do the research. Every ethanol plant will eventually need a new DCS and it’s not wise to wait until a system is on life support. Small failures can roll into catastrophic failures, so developing an upgrade plan with foresight will help reduce downtime during a system migration and eliminate maintenance cost pile-ups. Work with a current manufacturer and find a trusted independent systems integrator to customize the best solution for any site. Being proactive with upgrading an operating system will keep business in business, continuing to meet the needs of customers.

Author: Jason Hurst
CEO, Trident Automation