An advanced valve positioner is a digital valve control device that controls valve pneumatic actuators in response to commands from a Fieldbus control system using FOUNDATION protocol.

The Yokogawa YVP110 advanced valve positioner is a digital valve control device that controls valve pneumatic actuators in response to commands from a fieldbus control system. It communicates using the foundation fieldbus protocol. The YVP110 is a versatile component that minimises transmission lag, improves valve characteristics and response, and reduces flow-pressure variation effects.

It is designed for use in conjunction with Yokogawa's ValveNavi: a software tool that greatly facilitates the process of setting up, tuning, and maintaining the YVP110.

Today's field devices incorporate various self-diagnostic features, allowing external conditions to be diagnosed by the devices themselves.

This could include diagnostics of a valve by a valve positioner or checks for clogging in the pressure impulse line by a differential pressure transmitter.

To use these diagnostics effectively, mere transmission of simple process values and status is not enough: more information needs to be acquired from the field devices and presented to the user in a form that is easier to interpret and use.

An example of such an approach is the diagnostic functionality of the YVP110 valve positioner including the ValveNavi utility.

ValveNavi runs on a PC or as a plug-in for the plant resource management package to facilitate initial adjustment and parameter tuning, display trend graphs and diagnose the valves.

The YVP110 valve positioner features both online and offline diagnostics.

The online diagnostics include the device's own self-diagnostic functions plus online monitoring and integration of the valve operation information.

The offline diagnostics, also known as 'signature functions', include measurement of the input/output characteristics of the valve (input pressure versus valve position); measurement of the step responses of the positioner; and measurement of the input/output characteristics of the positioner.

The YVP110 contains a compact pressure sensor, and in operation scans the output pressure and measures the valve position.

After scanning and measurement, the software acquires the measured data via the Fieldbus, and displays the results as a graph.

The data can be saved in the computer and overlaid on past measurements for comparison to check changes in hysteresis and the slope of the curve.

As a result, anomalies such as looseness of the gland packing, damage to the return spring, clogging or erosion can be detected.

Input/output characteristics are measured at the various points in 10% increments as standard, but high-resolution signature measurement at more than 1000 points is available as an option.

Up to two sets of measured signature data can be saved to the device's non-volatile memory.

A typical example of a ValveNavi application is in displaying the step response of a valve/positioner system.

The step width and measurement period are set prior to measurement, and the response data measured in the positioner is displayed after measurement.

As with the input/output characteristics, the step response can be compared with past response data, allowing detection of excessive overshoot and limit cycle due to an anomaly in the actuator or positioner.

Up to 600 measurements can be sampled at variable intervals from 20 to 1000, so that various patterns of response can be obtained as required.

* About Yokogawa Electric Corporation - Yokogawa's global network of 18 manufacturing facilities, 83 affiliate companies, and over 650 sales and engineering offices spans 28 countries.

Since its founding in 1915, the US$4 billion company has been engaged in cutting-edge research and innovation, securing more than 7,000 patents and registrations, including the world's first digital sensors for flow and pressure measurement.

Industrial automation and control, test and measurement, information systems and industry support are the core businesses of Yokogawa.

* About Yokogawa Europe - the European headquarters were founded in Amersfoort, the Netherlands, in 1982.

Throughout Europe Yokogawa has its own sales, service and engineering operations.

This dedicated network has been extended to Central and East Europe and Southern Africa to further enhance the coverage and support associated with serving the process control and automation market place.

We develop and produce flowmeters at Rota Yokogawa in Germany, liquid analysers and industrial safety systems in the Netherlands.

In addition to this dedicated network of Yokogawa subsidiaries a select organisation of Test and Measurement (T and M) subsidiaries and distributors is established in certain areas to support the specific customer needs of this continuously developing and specific market of T and M instrumentation.

* About Yokogawa UK - Yokogawa UK, part of the global Yokogawa Corporation, is a supplier of enterprise technology solutions to the process, manufacturing and utility sectors.

The company is a technology and market leader in instrumentation and control, and holds many key patents and national and international approvals.