ABBs (www.abb.us/) vice president of global business development, John Murray, wasnt quite as specific but still provided sage advice. Users who choose the radical rip-and-replace strategy forego the opportunity to go back and typically incur larger upfront capital investments, experience major production downtime and acquire added costs in the areas of commissioning, training (engineers, operators and maintenance) and validation, explains Murray.
Murrays advice is right on the mark, but I would add one additional piece; discard any emotional baggage that is based on an unfounded grievance against a PAS manufacturer who says your system is now obsolete. A closer examination of the PAS modernization horror stories often revels that making hasty, emotional decisions contributed to eventual project problems.
Doing It Correctly
Each and every PAS manufacturer puts its own spin on whats required to successfully modernize an installed PAS solution, but when all the marketing talk is boiled away, the crucial steps that are required to do it correctly are
Identify and build a modernization business case, including
- Increased availability, throughput and safety
- Reduced manufacturing costs and plant emissions
- Improved product quality, response to customer requests, and ability to introduce new products.
- Conduct a detailed site assessment based on business objectives, including
- Key process measurements
- Process constraints, disturbances and limitations
- Equipment or operational limitations.
- Conduct a detailed use/requirements assessment and select a PAS modernization partner.
- Jointly develop a detailed evolution path and risk management strategy, including
Impact and resources required to replace I/O interface modules. Experienced migration specialists warn that this effort is frequently underestimated. You will be living with the I/O architecture for the next twenty or so years. Now is the time to get it right.
Interim interface cables and solutions between old and new equipment. Whenever possible, experts advise that it is best to go directly to the final solution. Even if it initially takes longer it will likely save time and reduce overall risk.
Third-party interfaces. Experts agree that much time can be saved by fully testing, in a controlled environment, all third-party interfaces, including the actual cables and connectors.
Full understanding of the state of the existing equipment, including its revision levels. All things considered, you may significantly reduce project risks by bringing all the existing (legacy) PAS devices to a common revision level before beginning any modernization efforts.
Control algorithms and tuning constants. Different PAS manufacturers use different PID (proportional, integral, derivative) algorithms that may result in undesired control actions if you plug in the old tuning constants. Understand what you have and what you are getting.
Defined terminology and agreed upon definitions. You and your PAS partners may be using the same words, but until those words have the same meaning to everyone project,t progress suffers.
Change management, or making the new PAS act like the old PAS. There will be some things that should not be changed, but you are paying for all sorts of new features and capabilities; why not take advantage of them now? If your argument against change is that you will get around to using the new features later, the reality is that you probably never will.
Footprint and layout. Newer systems generally require less space. Now may be the last time you get to rearrange cabinets, room layouts, etc. for a very long time.
Simulations. Development of simple database tiebacks from exported PAS databases and incorporating some first-principal models has become very easy. Not only can simulations help operators become familiar with the new system, but they also can also help ensure I/O points and other interfaces are functioning as expected.
Though this list represents a mere fraction of the elements users need to consider, developing a list that is relevant to your particular PAS situation does not have to be a stressful exercise, and you are not required, nor should you try to do it alone.
Stress-free retirement planning, whether for personnel or a PAS, requires a process and decision-making framework that covers an extended time horizon, draws from economics, leverages the advice and wisdom of experts who understand your unique requirements, considers a broad range of options and their influence on the outcome and is planned as though your job depends on it, because it probably does.
Dave Harrold is co-founder of the AFAB Group. He can be reached by e-mail at firstname.lastname@example.org.