Criticality of the installation
One of the most important factors in determining the scope of the control system upgrade is the criticality of the system.
The level of criticality depends on the application the unit is in. Redundancy of engines is the most important parameter here. Most installations, when newly built, have one or two units spare. This makes it possible to do routine maintenance on one unit, running the remaining units and still have one spare in case of sudden mishaps. However applications change.
Demand for availability increase
For example: offshore platform power generators tend to feed newly built satellite platforms. On gas compression stations the volume of gas being pumped increases every year. And with the free gas and electricity market the term ‘running season' seems to be no longer applicable. The result is that the demand for availability of the installation increases year by year - while at the same time the true availability of the installation decreases due to aging.
The role of the control system
The control system plays an important role in two aspects here:
- the availability of the system itself
- the quality of information it can provide to the operator about malfunctioning of the unit or system it is controlling
The question to pose is: what is the financial damage if I loose machine x on an event which is difficult (> 1 month) to repair?