In the past few years, we have seen changes to our controls projects' scope and nature. What used to be a landscape of greenfield projects now regularly includes smaller process additions and the upgrading of legacy control systems. Legacy control systems are upgraded for several different reasons, and the available solutions are just as varied. So, how can you determine what can or should be done? Let's start by asking why.
Why does the system need to be upgraded? As your control system ages, you need to identify, mitigate, and eliminate the obsolescence risks associated with a dated system. Some manufacturers cannot get the products they need to build legacy modules. As hardware lines are discontinued, it becomes challenging for plants to find the replacement components they need to keep their facilities functioning. There are also financial consequences from extended downtime from failed, unreliable and obsolete hardware and/or software. A proactive strategy will allow you to consider options to migrate products to newer technologies that are more easily obtained and supported, ensuring that critical spares are readily available, and facilities stay operational when they are needed most.
Control system failures are a possibility, and you need to be aware and prepared. One way to mitigate risks associated with the failure of a system is to perform an installed base evaluation. A good evaluation is more than just creating an inventory of your parts; it is a detailed analysis of your critical plant assets and these components' conditions. You'll obtain life cycle data on your aging equipment, thus allowing you to understand what is current, outdated or even obsolete. An installed base evaluation should include these essential components:
- Field Collection
- Delivery of Reports/Recommendations
- Implementation/Remediation Processes
If and when your control system needs to be upgraded, a design team can investigate the latest technologies and hardware solutions that best support your systems requirements. New technologies such as HART-enabled analog I/O modules can leverage increased capabilities in either existing or new instruments. Ethernet communications allow current technologies to be used but may require cabling installations, in addition to new networking hardware, to be implemented.
During the design and implementation of an upgrade is an opportune time to update your control system documentation. Documentation can be generated as basic as to support the upgrade components and wiring needed, or as extensive to document where each control signal for motors and devices are connected to the control system.
There are many options to consider when determining how best to upgrade a control system, and there is no one-size-fits-all answer. If your control system is aging and you do not yet have a plan for mitigating current or future risks, take a proactive approach and engage your design team to help recommend the solution(s) that best fit your facility and needs.
Jamie Schmidt & Jeff White