Circuit diagram

A circuit diagram , also known as a circuit diagram or circuit diagram , is a graphic representation of an electrical circuit used in electrical engineering and electrical installation technology, mostly at the level of individual modules or elements used in electrical installation technology such as switches , fuses , contactors , electric motors or light bulbs . It does not take into account the real shape and arrangement of the components, but is an abstract representation of the electrical functions and the current flow.

A circuit diagram is usually understood as a document that is addressed to the customer, an approval authority, the builder or the maintenance electrician. Some of the symbols used overlap with the circuit diagrams used in the electronics .

Basics

Circuit diagram and circuit diagram and their symbols

(Mostly standardized) symbols are used. In addition, there is a designation system in which each component is assigned to a group and finally receives an identification number. Reference information enables you to find it quickly within the plan.

By definition, circuit diagrams should represent the switched-off, de-energized and empty situation of the associated machine or system. If there is a deviation from this, this must be explained by means of a written notice (e.g. "container full"). Circuit diagrams belong to the function-related documents according to DIN EN 61082. These plans are created at the beginning of the design of a system, device or assembly and are also required later for repairs and maintenance.

General

Electrical circuit diagrams can be created individually, company-specifically or according to standards , for which the following current standard specifications exist, for example:

DIN EN 60617 Graphic symbols for circuit diagrams
DIN EN 61082 documents of electrical engineering
DIN EN 61355 Classification and marking of documents for plants, systems and facilities

The elements of the circuit ( electrical equipment and lines ) are represented by standardized circuit symbols , also known as symbols. You can use all or parts of it, such as B. working circuits or just control circuits, the steps of the workflow , the components of the circuit with their identification and the lines and connections. The spatial arrangement of the components is usually not taken into account.

In industrial production , the circuit diagrams can be supplemented with additional documents such as assembly plans , wiring plans , terminal plans , etc.

Execution types

Some typical types of circuit diagrams in electrical installation technology are particularly common in practice:

The operating diagram , sometimes called "circuit diagram in a coherent representation" -, the circuit is such that the effect relationship is visible, mechanical, for example, by adjacent positioning of the symbols functionally of related components and additional symbol display lines of action. All components of the circuit are included in the plan, roughly true to the real structure.

The circuit diagram , sometimes also called "circuit diagram in exploded view" to distinguish it, represents the circuit strictly according to the individual current flow sequence of the components, the operative connection results from the tracking of the alphanumeric identifications of related parts (signal names) so that several pages are used to represent a device can. In electrical circuit diagrams, the outer conductors , neutral conductors and protective conductors of the main supply lines usually run horizontally at the upper and lower edge over the entire drawing. The individual current paths are drawn in between. The circuit diagram, which is often several meters long, can then also be divided into sections with specific assemblies (motor circuits, control circuits, lighting, etc.).

The current paths drawn vertically are numbered to allow referencing. The links between the assemblies, which are far apart on the plan, are established using references. Particularly prominent potentials are marked with an identifier in order to avoid repeated turning of pages and searches. The same applies to assemblies and components, which are also marked in a special way. A characteristic of the circuit diagram is that it is drawn as free of intersections as possible so that the paths do not overlap. That is why the PE conductor is usually left out in electrical energy and building technology , as otherwise the connection of the vertical paths with the protective conductor inevitably leads to a crossover with the outer or neutral conductor .

The line diagram is a variant of the circuit diagram, "one-dimensional" view in which are running parallel lines, inter alia, with the same components result to the drawing summarizes the number of parallel strands is marked by dashes or numbers. This is particularly the case with circuits with numerous three- to five-pole three - phase cables or also parallel data buses. Electronic circuits can be combined into function blocks ( block diagram ).

The installation plan is similar to the general plan, except that in addition to showing the wiring, the installation plan also shows the furniture, doors and windows of the room to be developed.

A single line diagram is a simplified form of the circuit diagram which is primarily used in the field of electrical energy technology such as power plant construction. In single-line diagrams, circuits, including multi-phase circuits, are reduced to simple lines, which allows a rough overview.

Laws and norms

DIN EN 88 Graphic symbols for circuit diagrams
DIN EN 61355 Classification and marking of documents for plants, systems and facilities

literature

Alfred Windmüller: Circuit diagrams in heavy current control technology as a means of increasing performance ; Mannheim; Brown, Boveri & Cie; 1942
Joachim Weinert: Circuit drawing in electrical power engineering . 4th edition, Carl Hanser Verlag, Munich and Vienna, 1981, ISBN 3-446-13436-0
Hans-Günter Boy, Uwe Dunkhase: Electrical installation technology The master's examination . 12th edition, Vogel Buchverlag, Oldenburg and Würzburg, 2007, ISBN 978-3-8343-3079-6
Winfrid Hauke, Rolf Thaele, Günter Reck: RWE Energie Bau-Handbuch. 12th edition, Energie-Verlag GmbH, Heidelberg, 1998, ISBN 3-87200-700-9