Transmitters as part of an Asset Management System

Edited by the Engineeringtalk editorial team Jan 22, 2002

Utilising smart transmitters for anomaly detection, in addition to introducing open-networking and on-line software systems, will ultimately improve both economic efficiency and plant performance

The most important task for control engineers today is to increase the economic efficiency of their industrial plants.

Optimisation of the process control system has been on the agenda for many years, with the development of advanced control software improving targets.

Further efficiency improvements are expected to derive from increasing plant availability and reducing maintenance, which will have a big impact on improving economic efficiency.

Increasing plant availability requires improving component availability, which can be achieved through the early detection of anomalies in the equipment, and by providing real-time maintenance.

Understanding the failure rate of various pieces of equipment is key to a predictive maintenance program.

It is of equal importance to know when an instrument is fully functioning, as it is to know when it has failed.

If the health of an instrument were known at all times, those unnecessary maintenance trips could be eradicated.

There have been many attempts to improve plant availability by applying signal validation schemes to process control systems.

To detect signal anomalies in the past, engineers would utilise consistency checking or model-based techniques, whereby the normal behaviour of a sensor is modelled by auto-regression time series and then its behaviour monitored.

Signal validation has since been integrated with high-level control systems and their data acquisition systems.

However, these schemes showed signs of inefficiency.

Occurrences of signal linearisation, damping, and communication delays can mask the true readings of the sensors, and could result in the loss of critical information hidden in the raw data, rendering the results inaccurate.

Transmitters are devices that contact processes and provide measurements on these processes.

However, performing anomaly detection is another task.

Driven by demands to improve asset management and diagnostics technology, considerable advances have occurred in communications and software over recent years, leading to a new generation system of 'field-based systems'.

Field-based systems provide the ability to network field devices, such as sensors, valves and motors, with controls and asset management systems to offer an integrated information system that can be used for both control and automated maintenance.

In a modern field-based network, the transmitter is able to provide diagnostics information on the health of the sensor and the health of the general process, including the condition of equipment connected to the process, such as the valve and compressor.

Transmitters can now be made aware of changes in their environment.

Asset Management can be defined by 'properly maintaining product equipment to deliver maximum performance and service life at minimal cost'.

Included in the asset management system are smart field devices, namely transmitters, communication protocol and on-line software.

The foundation of an integrated plant Asset Management System is to provide a standard set of diagnostics from networked field devices and provide advanced maintenance scheduling.

The ultimate aim of the Asset Management System will be to increase plant uptime and reduce maintenance costs.

Utilising smart transmitters for anomaly detection, in addition to introducing open-networking and on-line software systems, will ultimately improve both economic efficiency and plant performance.

As industry increasingly demands improved performance, productivity and efficiency, the transmitter's function and responsibility in the process is expected to change dramatically.