…from an existing offshore manned platform was analyzed to compare the different combinations of capital cost of the as built wired / Foundation fieldbus versus Electronic Marshalling technology. The results show cost savings of between 7% and 26% which equates to $0.3M to $1.25M, depending on the options chosen, with additional value of saving of up to 30 tonnes in weight and up to 43 m2 of deck space in cabling, cable tray, junction boxes and cabinets.
The scope of the study includes materials and labor for a manned, offshore platform and its process automation system and associated cabling, cable tray, marshalling cabinets, system cabinets, controller I/O cards, and control room space requirements. David describes the layout:
The Control Room is situated at one end of the Platform, such that the average cable length on the cable tray is about 90 metres. In that room are System Cabinets containing controllers and I/O cards. From there, the cabling continues to Marshalling Cabinets, then onto cable tray which runs out onto the platform. At various positions on the platform, cabling exits the cable tray to local Junction Boxes. From the Junction Boxes, there is an average of 10 metres of cable to each field device, and in the case of a Fieldbus loop an average of 5 metres between the junction box and megablock and the megablock and the field device.
The cost analysis first considers the number of I/O that could be wireless I/O, based on the speed of the control loop or monitoring application. Based on the platform topology 30 wireless I/O can be connected per wireless network.
The whitepaper compares these scenarios:
- Conventional wired with Fieldbus (separate power) – as built
- Conventional wired, Control Room Electronic Marshalling with Fieldbus (separate power)
- Conventional wired, Field Electronic Marshalling with Fieldbus (separate power)
- Conventional wired, Field Electronic Marshalling with Fieldbus (integrated power)
- Conventional wired, Field Electronic Marshalling, Fieldbus (integrated power) and wireless devices
Pages 8-10 of the whitepaper show the I/O mixes used in the calculations. The savings, presented on page 12, range from 6.8% to 25.6% for the 1874 total number of points considered.
David has developed a calculator that an Emerson local business partner or sales office can apply to your application to how these I/O on Demand technologies can impact the financial costs of your project.