"You need to do both measurement and control devices," he adds. "Your plant performance will only be as strong as your weakest link."
Jeff Dobos, president of ProComSol and developer of DevCom2000 PC-based HART communicator software, notes that in the past the use of a PC-based HART communicator in plant environments could be awkward at best. "Carrying a laptop up a ladder is dangerous," Dobos admits, "but the advent of wireless Bluetooth-to-HART modems has changed that. Connect the Bluetooth HART modem in the hard-to-reach location, climb back down and use your PC-based HART communicator safely from the ground." Of course another option is to connect the HART modem anywhere on the 4-20mA loop.
Setting the Stage for Fulltime Connectivity
As valuable as it is, offline HART connectivity through handhelds, communicators and portable PCs really represents only the opening volley in the HART value proposition. To realize the full potential for HART communication to enable improved plant reliability, a significant and growing number of users are moving to full-time, integrated HART connectivity.
Back at We Energies, for example, the Valley Plant has progressed to HART instrument communications that are fully integrated with its process control and asset management systems. Automated valve tests run seamlessly in the background, kicking off tiered levels of alerts -- all using HART. If no issues are detected in the course of an automated test, no alerts are generated. Issues that need attention -- but are not expected to affect operations in the near term -- go straight to a workstation running Emerson Process Management's AMS Suite asset management software for subsequent resolution. Only issues that the operator really needs to know about go to the Emerson Ovation control system operator console. "We're leveraging HART to do proactive diagnostics," Gordon explains. "We want to solve problems before they appear to the operator."
The power plant also uses WirelessHART to boost safety and to quickly and easily add new measurement points. One example was a hard-to-reach temperature transmitter and thermocouple that had been installed five years ago, "but we never pulled a cable," Gordon says. WirelessHART solved that problem in short order. The company also uses WirelessHART to monitor safety showers and eyewash stations scattered through the remote areas of the plant.
Today, the plant is migrating standalone local control loops over to HART-based digital valve controllers and transmitters. Similarly, on/off valves are being retrofitted with digital valve controllers to provide diagnostic capabilities over HART. "With HART and a digital valve controller, I can remotely run a five-minute valve test and tell whether the valve is leaking through without ever taking anything apart," Gordon says.
"HART technology has made our job of keeping things up and running a lot easier," Gordon says. "When you look at how we previously used HART versus what we do with it now, it's an incredible leap in technology. Today, our rule of thumb is that if a device we're buying comes with HART, we want it."