Selection of Automation Equipment

Now that the essential aspects of the project design work have been explained, the following article concentrates on the equally important questions in this context of the selection of automation equipment. These selections are particularly relevant for the preparation of the EMCS block diagrams and equipment lists since, apart from the functional integration of the automation equipment into these diagrams, their layout is also of importance (e.g. measuring ranges/sensors and correcting ranges/actuators).

In general, the task of the project engineer is to select the automation equipment so that it represents the optimum solution for the automation system to be constructed. Initially, the following generally applicable requirements can be listed for this:

>> Realisability

The automation task is to be solved by an appropriate means of automation equipment.

>> Reliability

The fail-safe aspect of the automation equipment used must be adequate for the operation of hazardous processes.

>> Process condition

The conditions characteristic of process technology operations such as temperatures, pressures, aggressive media, explosion risks, irradiation, electro-magnetic fields etc, must be taken into consideration as a whole.

>> Customer requirements

Customers frequently specify from which manufacturer and with what functionality the automation equipment is to be procured.

>> Integratability

It should be possible to realise the expansion of an existing automation system by means of additional automation equipment with the least possible expense/trouble (e.g. without changing of existing auxiliary energy).

>> Energy consumption

The energy directly taken up by the automation equipment (auxiliary energy) or the energy expenditure required in the process (e.g. control valves, pump motors, etc.) is to be utilised in the most efficient way possible.

>> Cost determinants

The price comparison of different automation equipment for the solution of an equivalent task represents an important factor of project costing.

>> Miscellaneous

The aspects to be considered under this heading are, for instance, size, weight, possible installation of automation equipment, customer service, etc.


Moreover, the importance of the various evaluations of these requirements should be considered in this context whereby, for instance, the guarantee of process reliability is always of greater importance than a reduction of costs. If we now revert back to the already mentioned small-scale experimental modules or other process technology systems, then the analysis of the PI flow diagrams and the EMCS block diagrams clearly shows that the selection of automation equipment mainly applies to actuators and sensors.