Service Brief – Control System Migrations

Introduction

In the ever-changing control system world sites are often faced with a migration from an older, perhaps obsolete, control system to a different or modern platform. These projects can vary from a ‘simple’ Human Machine Interface (HMI) replacement to a full platform replacement, including controllers and I/O subsystem. These are often expensive and can take place over many years. However, they also provide an opportunity to make some significant improvements to the design to bring the system closer to current standards and best practices. This is where UCDS can help by providing services to support your project team.

HMI replacement

Consider first a replacement of the HMI. It is not uncommon for system vendors to update their HMI systems with ones that take advantage of new technologies, especially as older technologies become obsolete.

The simplest option is to simply replace the current systems like for like, often citing operator familiarity with the existing and the lack of time to train them on a new system. Although this seems simple, often there are constraints on the new systems that still means some compromise in the design. This is especially true with older HMIs that are configured with heavy scripting to implement features not native to the platform. Navigation is a good example of this.

The biggest issue with this approach is that there is little return on investment (ROI), and it is a big investment.

So where are the opportunities to generate some ROI or even some project cost savings?

From an ROI perspective an improvement in operator performance can ensure that the operator makes fewer errors and thereby reduce downtime, reduce off-spec material, and possibly avoid environmental and safety incidents. This requires that changes to the system to improve the operator’s situational awareness are made. For example:

• Improved navigation – adopting a hierarchical information and navigation system can significantly improve the operator’s ability to detect a problem, diagnose the problem and act. A true Level 1 display will help the operator identify issues before they go into the alarm state and direct the operator to the appropriate Level 2 where they can diagnose and act on a single screen.
• Improved graphic design – ensuring that graphics are designed to facilitate the operator’s tasks and improve situational awareness by adopting best practices such as layout and color usage.
• Optimized console design – ensuring that the console is designed to meet ergonomic best practice and to accommodate the appropriate number and layout of screens, including any large screen displays.

By implementing a proper hierarchy and optimizing Level 3 and Level 4 design can also result in a lower total number of graphics that reduces project costs and future maintenance costs.

Complete platform replacement

With a complete platform change it should be obvious that the improvements associated with replacing the HMI can be achieved. However, there are some other potential improvements that can be made when replacing controllers and the reconfiguration effort required for that.

• Improved alarm management – this is an ideal opportunity to look at implementing improvements to the alarm management system. This is not just rationalizing alarms, although updating static and dynamic alarms is beneficial, it is also an opportunity to adopt state-of-the-art alarm management software that can simplify complex controller-based alarm management. This might include functions such as alarm help, alarm enforcement and a state engine to manage dynamic alarming.
• Optimized operator workload – many older systems are inflexible when assigning equipment to a console. More modern systems are more flexible and allow assignment across controllers that can facilitate load balancing of operator workload. This can be determined from an operator workload study. With improved systems this may also allow for consolidation of console positions to reduce headcount.

Summary

A control system migration is a good opportunity to make improvements that can reduce operator error and thereby reduce off normal and abnormal operations leading to less downtime and unwanted incidents. Improvements can increase ROI and potentially project and long-term maintenance and operations costs.

UCDS can be a trusted partner to help guide you through the process.

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