NN Asks: What have recent projects taught us about the move from analog to digital plant controls?

A great example is testing digital distributed control systems in the main control room (MCR) and the remote shutdown room (RSR) of an AP1000 plant, which utilize separate operator workstations digitally tied to the same computer.

Recent projects have taught us that getting digital I&C right requires a complete rewrite of our traditional testing and commissioning programs. Because modern reactor protection systems utilize digital controls, we can shift the risk profile by validating internal signals at the factory during assembly. This reduces the duration of the on-site testing program, focusing on ensuring field connections are correct and then conducting integrated testing.

The biggest pitfall for legacy commissioning teams is adding unnecessary layers of redundancy by treating digital logic like independent analog loops. For example, rather than validating alarms in both the MCR and the RSR, we can validate the software logic once, yielding significant time savings.

Ultimately, successful digital integration requires us to change our mindsets as much as our technologies. Modern I&C streamlines construction schedules and maximizes data clarity, but it still relies on foundational human expertise. Getting I&C right means recognizing that advanced technology is only as reliable as the engineers who bridge the gap between software and hardware.

Thomas Burnelis (burnelta@westinghouse.com) is the manager of electrical and controls integration at Westinghouse Electric Company. His current and previous expertise includes plant integration, AP1000 plant commissioning, and senior reactor operator/I&C training.