There has been a long term trend towards centralised control and monitoring of plant and distributed assets. This has been driven by advances in technology, economic pressures and generally higher expectations of management and
For instance, with through the availability of smart phones and access
to the web, it is not unusual for utilities to have centralised control systems
which communicate to portable, mobile devices. An example is the ROAMES (Remote Observation Automated Modelling Economic Simulation) project developed by Ergon Energy. For a given project or plant, the question is to what extent is centralised control and monitoring required? What are the benefits and what is the cost? This may be further complicated for a brownfield site, where there are legacy systems and operations procedures.
Items to consider are:
- Is it a valid to expect to operate and control a new part of the plant in the same way which was used for the section of plant which has been operating for maybe 20 years?
- What changes will be required to interface the new with the old?
- How will the new system be implemented?
- Is there a need to consider upgrading the legacy equipment?
- What is the budget?
- Should there be centralised monitoring?
- If automation is required, would this be centralised or part of the local equipment?
If installed, what is to be the method of control? Are they to be hardwired to a central Motor Control Centre or should remote PLC inputs / outputs be considered. Other factors affecting the detailed design may be:
- Safety – Emergency stop
- Maintenance – Local lockout
- Permissive control – Central permission
Finally, the application will have a big influence. For example, the automation of a remote substation in the distribution network would not be the same as the local / remote control of a boiler feed water pump in a power station.