Industrial Control Systems
The term Control System, in its broadest sense, can apply to a very wide
range of different systems that operate at different levels within an industrial
system. One good way to classify different types of control systems is
in terms of functionality:
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level 0 - emergency shut down system (ESD) - contains all the fail-safe
mechanisms for the system
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level 1 - low level control - direct control of actuators
-
level 2 - supervisory control - co-ordination of several, or plant-wide,
low level controllers
-
level 3 - management systems - including resource planning systems and
management information systems
These levels have a very different emphasis for each type of control system
application. For example simple servo control applications have very little
in terms of the upper-most level, whereas a within a Chemical plant the
level 0 systems are critical to plant safety, but level 3 systems are the
ones that improve the economics of the plant.
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