Siemens pa module p03-01 manual Theory, Hierarchy Of Flow Diagrams, Multi purpose plant, Curves

Industry Sector, IA&DT

THEORY

HIERARCHY OF FLOW DIAGRAMS

In chapter P02-01 the objectives of process control as well as of basic design concepts and techniques for OCM interfaces (operator control and monitoring interfaces) were described.

Chapter P01-03 introduced the physical model of a system consisting of a plant, a plant section, equipment module and an individual control unit. Analogously, a hierarchy of flow diagrams exists in process visualization that is arranged as follows, according to [1]:

–Plant diagram

–Area diagram

–Plant section/group diagram

–Detail diagram

The hierarchy of the flow diagram facilitates orientation and specific display selection. The uppermost levels Plant display and Area display provide an overview and are usually represented schematically. In small plants, the plant display corresponds to the area display (refer to Figure 1). In the plant display, it has to be possible to select each area directly. In the area display, the plant sections are displayed in a manner that their state can be recognized and the plant section can be selected and operated. The plant section and group display reflect functional relationships; typical units, final control units and control systems can be operated. Detail displays are of great importance to parameter assignment, commissioning and error search if there are plant faults. In detail displays, individual devices and units are represented and by means of effective lines, the functional relationships can be visualized. For example, the signal flow of a control loop can be tracked. [1].

Multi purpose plant

Educt tanks Reaction Product tanks Rinsing

Tank 1	Tank 2	Tank 3	Reactor	Reactor	Tank 1	Tank 2	Tank 1
			1	2

Figure 1: Hierarchy of mimics

CURVES

Plant and area

display

Plant section

display

Detail display

Curves are used for process control during intended operation, or for diagnosing faults [2]. They supplement the display with flow diagrams, particularly because they indicate the dependence of process values on time.

Related displays are: the display of a process value depending on the path, on other process variables, and even of several reference variables that are not described here, however.

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