Smart valve positioners are digital valve controllers, microprocessor-based, current to pneumatic instruments with internal logic capability. They are designed to convert a current signal to a pressure signal to operate a valve. The ability to embed software commands into the memory of these smart digital controllers represents the real difference between digital and analog I/P devices. The software capability allows automatic configuration and setup of the valve when equipped with a digital controller. Most importantly, it allows two-way communication for process, valve, and instrument diagnostics.
Reasons for the Use of Smart Positioners
In most respects smart positioners perform the same basic function as the basic analogue positioners combined with current to pneumatic converters. However, the key advantages for using smart positioners are:
- Automatic calibration and configuration. Considerable time savings are realized over traditional zero and spanning.
- Valve diagnostics. Through the Distributed Control System (DCS), PC software tools, or handheld communicators, users can diagnose the health of a control valve while it is in the line.
- Reduced cost of loop commissioning, including installation and calibration.
- Use of diagnostics to maintain loop performance levels
- Improved process control accuracy that reduces process variability
