Considerations in Control System Modernization Projects

Emerson’s Laurie Ben and John Dolenc will be teaming up at the year’s Emerson Exchange to present Modernizations & Migrations: Lessons Learned. The workshop is in two parts because of the vast ground they cover with respect to control system modernization and migration. Part 1 addresses an overview of modernization and migration projects, choosing the appropriate strategy, ROI-based project justification, and cost impacts. Part 2 addresses risk mitigation, best practices, and lessons learned.

In this post, I’ll zero in on the strategy portion of their presentation and save the rest for those that join their workshops in San Antonio. Once the decision is made that something needs to be done with the existing control system, a number of migration issues face the plant staff. Questions include:

  • What will be gained in the process?
  • Who can do the plan/design/implementation/startup required?
  • How much will it cost?
  • How long will it take?
  • Will the process need to be shutdown and if so for how long?
  • What are the other risks such as delayed startup and off-spec product?
  • How will these risks be mitigated?

These are fundamental questions without easy answers. Perhaps this is why ARC estimates $53 billion (USD) in installed control systems are more than 20 years old.

Migration projects differ from new projects in many ways. Documentation may not be available or is often out of date. New control system equipment needs to fit into existing space. Some process units are not shutdown for years at a time so a hot cutover procedure needs to be implemented. If the migration is performed while the process is shut down (cold cutover), the time window is usually short and the project must be meticulously planned. Intensive testing of the new control strategies is required to ensure a successful startup–avoiding lost production. Finally, operations expectations need to be identified and implemented so they’ll see the operational improvements with the modern automation equipment.

Three migration strategies include as-found, functional replacement, and modernization. As found means that the functionality of the new control system exactly mimics the existing system. A functional replacement migrates the functionality of the existing system but takes advantage of the modern technologies where possible. Modernization considers all the capabilities in the new system to apply to the control objectives of the process–a clean sheet approach. This extends beyond the control system to field devices such as smart instruments, digital valve controllers, and asset protection equipment.

The scope of the migration can range from an entire control system replacement at one time, to a multi-phased approach that replaces portions of the control system at a time. Vertical or horizontal phased migration approaches may be used. A vertical migration is performed process area by process area. A horizontal migration is control system platform-focused: I/O card replacement, controller replacement, and operator workstation replacement.

Laurie and John share examples of horizontal migrations where field wiring is left untouched by marshalling field signals from the existing terminations to the new control system I/O. Based on the make and model of the existing control system, they also share ways to migrate operator workstations and/or the controllers while maintaining the existing I/O infrastructure.

If you’ll be at the Emerson Exchange and are in the process of evaluating your control system modernization options, you’ll want to attend both parts of Laurie and John’s workshops. There are many lessons learned based on the years of experience from helping perform these modernization and migration projects.

GreenPodcast.gif MP3 | iTunes

Audio clip: Adobe Flash Player (version 9 or above) is required to play this audio clip. Download the latest version here. You also need to have JavaScript enabled in your browser.

Leave a Reply