ARC Advisory Group‘s recently published ARC View, Emerson Brings DeltaV SIS into the Future with Version 11 Release, describes the continuing advancements of the DeltaV SIS safety instrumented system. DeltaV SIS launched over 5 years ago and this whitepaper provides an update of its original and continuing objectives:
Emerson designed DeltaV SIS to address the issues that face safety system end users today, from flexibility in design to increased reliability, increased visibility into the system, reduced complexity, and easier regulatory compliance.
The flexibility is described:
DeltaV SIS can support a simplex or redundant logic solver. Both are certified for SIL 3 applications. Each logic solver has 16 integrated I/O channels. These are software configurable, eliminating the need for separate I/O cards.
The SIS scales from an individual logic solver upwards:
Emerson has also considerably increased the potential size of DeltaV SIS systems to the point where they can handle very large applications. The architecture can expand from a single 16-channel logic solver to 30,000 I/O… SISNet Domains further increase design flexibility, provide improved support for large projects, easier expansion of existing systems, and easier isolation of separate SIS applications. Basically, this eliminates the capacity limits for DeltaV SIS.
The purpose of a safety instrumented system is of course to take the process to a safety state if it enters a hazardous operating condition. The flip side is that you don’t want the SIS to shut down the process when it shouldn’t, such as in the case of a failure of a transmitter or final element. The whitepaper notes where the reliability concerns in a safety instrumented function (SIF) typically occur:
When it comes to safety system reliability, most failures are the result of a faulty valve or sensor. Emerson’s recent enhancements to its 3051 S intelligent pressure transmitter for SIS applications include plugged impulse line detection. Emerson’s DVC6000 SIS intelligent valve positioner for SIS applications includes partial stroke testing capabilities.
Diagnostics from these intelligent sensors and digital valve controllers within each SIF are sent back to the DeltaV SIS logic solvers to help identify problems in advance, before a spurious trip occurs.
Increased visibility with the process automation system occurs because:
…integration of the control and safety system in the operations, maintenance, and engineering environments, but provides complete physical separation of control and safety hardware, software, and communication networks. This separation of the basic process control system (BPCS) and safety system hardware provides the independence necessary to eliminate the possibility of common mode failures.
Though physically separated, the advantages of this integration:
…are reduced costs due to common HMI and software tools, and, more importantly, increased visibility into the process. The integrated architecture allows the user to see everything that happens in their SIS, including device diagnostics and alerts. It allows the user to take a proactive maintenance approach by addressing problems before they become incidents, such as through partial stroke testing and plugged impulse line detection.
The final point, easier regulatory compliance involves not only the functions within the SIS, but the people and processes required in a process manufacturer’s IEC 61511 safety compliance efforts. The Syncade smart operations management software can play a role in this work process management. Noted in the whitepaper:
Now the same level of integration between the DeltaV control system and Syncade is available between Syncade and DeltaV SIS. This greatly eases the process of safety system validation, competency management, document management, and workflow management. The document management capability of Syncade can help users be sure they are doing things properly from one phase of the safety lifecycle to the next.
Regulatory compliance is also assisted by the AMS Asset Portal, built on Meridium technology, which measures:
…key performance indicators such as overall equipment effectiveness (OEE).