The PCT loop concept not only helps you to comply with DIN and ISA, but also NAMUR recommendations (e.g. NA 50) during plant planning. Structuring of the PCT plant is carried out in the pre-planning navigator. You can create, edit and manage structure segments, PCT loops, PCT loop functions, containers and general planning objects in the pre-planning navigator.
PCT loops
PCT loops are managed in parallel to general planning objects, and behave in a way similar to them in the pre-planning. At PCT loops, macros can be stored, but not parts or function templates. PCT loops are either loops or consumers.
PCT loops are also called MSR loops or EI&C loops. EI&C stands for electrical, instrumentation and control engineering. The term PCT loop is used in EPLAN. The abbreviation "PCT" stands for process control technology.
PCT loop numbers
Together with the designation of the PCT loop, the PCT loop number allows identification of a PCT loop in the plant structure. Compared to general planning objects, PCT loops have the additional properties listed below. On the basis of these properties, the PCT loop number is automatically compiled.
- Technical facility: You can assign an optional further identifier to the PCT loop through this property.
- Measurand: The measurand describes the process value of the PCT loop.
- Processing function: A PCT loop can have multiple processing functions. The processing functions describe the tasks of the PCT loop functions assigned to the PCT loop.
- Number: This PCT loop number element is mandatory in EPLAN. This number allows PCT loops to be systematically sequentially numbered and, if desired, a distinction can be made between PCT loops with the same measurand and processing functions.
The number element of the PCT loop number is numbered when PCT loops are copied and pasted in accordance with the configuration of the segment definitions. PCT loops can also be renumbered subsequently in the pre-planning navigator and in the property dialog. The other PCT loop number components (such as the measurand) are only taken into consideration during numbering if these properties have been defined as identifying in the numbering settings.
Representation of PCT loops in accordance with the standard DIN EN 62424
The following three properties are available in the property dialog of the PCT loops for representation of PCT loops in the P&I diagram in accordance with the standard DIN EN 62424:
- Relevant to safety (ID 44060)
- GMP-relevant (ID 44061)
- Quality-relevant (ID 44062).
On the basis of the symbols displayed additionally in the graphical editor you can recognize whether a placed measuring point or consumer is relevant to safety, or GMP- or quality-relevant.
If the associated check boxes in the property table are activated and the properties added on the View tab of a property arrangement, the following additional symbols are then displayed at the components of the placed measuring points and consumers:
|
Symbol |
Meaning |
|---|---|
|
|
Relevant to safety |
|
|
GMP-relevant |
|
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Quality-relevant |
These special properties can also be output in the reports, the labeling and the block properties for the planning objects (for example at the "Pre-planning: Planning object plan" report type in a "Data sheet PCT loops"). In order to also display the symbols in accordance with the standard DIN EN 62424 for the safety-, GMP- or quality-relevant PCT loops on the report pages, you can use the technology via the form property Assignment Property / value to graphic (ID 13026). The symbols PCS_SQU, PCS_CIR and PCS_TRI are available in the GRAPHICS symbol library for the assignment of the graphic in the dialog of the same name.
PCT loop functions
The PCT loop function describes a subfunction of the PCT loop. This may be either a measuring or a consumer function.
Containers
In process engineering, containers belong to the apparatus group. They can be a plant element and are inserted below a structure segment level.
Containers are managed in parallel to general planning objects, and behave in a way similar to them in the pre-planning. Function templates and external documents / pages can be stored at a container, but not PLC addresses, parts or macros. Accordingly the properties dialog of a container only disposes of the Container general tab, which corresponds to that of a planning object, and of the Documents / Pages and Templates tabs.
A container can be inserted in pre-planning below a structure segment, but not below a planning object or a PCT loop. The containers themselves can also contain PCT loops and planning objects in their structure.
See also
Creating and Editing Structure Segments
Creating Planning Objects, PCT Loops, PCT Loop Functions, Containers and Connection Planning Objects