JDI Contracts worked with a major EPC and end user to study the project impact of wireless. They compared engineering, construction, startup and overhead costs for approaches using wired HART, wired bus technologies, WirelessHART, and combinations of each. Wireless was used for non-safety, low speed control and monitoring, amounting to about 25% of the total points.
Overall plant engineering, construction and startup savings were about 10% of considered costs as compared with wired HART; for the bus installation, wireless savings were on par with wired busing. Although not quantified, other considerations of flexibility and schedule impact were deemed very important in each approach:
Case 4, an integrated approach to using wireless together with Foundation fieldbus, DeviceNet, and 4-20mA hardwired HART was deemed optimal.
“By implementing wireless with other technologies, we found we could deliver a smarter plant at the same or lower cost,” says Roger Hoyum, principal engineer, JDI Contracts.
According to Hoyum, wireless benefits accrued to nearly every aspect of the project:
- Engineering: Reduced complexity and simplified application.
- Construction: Reduced scope, simplified installation.
- Startup: Highly flexible, responsive to changing needs.
- Overheads: Schedule savings translate to significant costs savings.