Gone are the days of Buttons and Switch’s. In almost all facilities we now use Distributed Control, Programmable Logic Controllers and Human Machine Interfaces. The primary advantage of this type of system is the ability to retain history. If we look at older control systems we could start, stop and monitor the process but we really had little indication of where the system variables were going or where they had been. In the event of a trip or failure we received some annunciation and alarm bells but little indication as to the root cause or sequence of events leading up to the trip.
By adding a Computerised Control system, the data collected from a process can be archived against time and reviewed or trended allowing historical revenue. Typical operation is not done by looking at pictures representing the physical path but by monitoring of trend lines and data. In this way operators can spot changes in given parameters which may highlight a potential issue.