Contacto normalmente abierto, NA. Contacto normalmente cerrado, NC. Se produce primero la apertura del contacto NC y luego el cierre del contacto NA. Contacto conmutado NANA. Se produce primero el cierre del contacto NA y luego la apertura del contacto NC.
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General description Introduction Structure of the database Normative references How to use existing symbols Choice of symbols Symbol size Orientation of symbols Representation of terminals How to create a new symbol from existing elements How to process requests for new symbols General description Symbols by: Symbol identity no.
It defines an international "pictorial language" used in electrotechnical diagrams. In a way similar to how words can be combined to form more complex expressions and meanings, the pictorial representations of this standard can be combined to build more expressive or specialised symbols. The concept "graphical symbol" is normally defined as a visually perceptible figure used to transmit information independently of language. Contact Support material: Drawing grid template Maintenance: For the purposes of the IEC the notion of a graphical symbol is somewhat broader to encompass objects that contain information on concepts including their associated graphical representations.
Each object has an identifier symbol identity number , a name, a status level, a graphical representation and a set of optional attributes.
These are described as follows: Application notes Symbol identity number an identifier of the form "Snnnnn" where n is an integer from 0 to 9. The numbers are sequential but carry no semantic meaning. CR by number a short description of the meaning of the symbol CR for action Alternative names synonymous, "almost synonymous" and possibly branch specific names, etc.
When a symbol is approved, its status is set to "Standard". If the symbol is later replaced by another, or if it is deemed technically obsolete, its status becomes "Obsolete - for information only". In the case of technical obsolescence the symbol may still be used, although it is no longer maintained.
These are also entered into the database as application notes, referenced from the symbols where they mainly apply. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies. The entry "Application Class" indicates for which kind s of diagram a symbol is intended. The defined application classes are: Overview diagram including Block diagrams, "Single-line diagrams", etc.
Relatively simple diagram, often using single line representation, showing the main interrelations or connections among the items within a system, subsystem, installation, part, equipment, software etc. NOTE — This document kind can serve as an overview on different levels for circuit diagrams and function diagrams as well.
Function diagram including Logic-function diagrams, Equivalent-circuit diagrams, etc. Diagram showing details of theoretical or ideal operation of a system, sub-station, installation, part, equipment, software, etc, by means of theoretical or ideal circuits This is a preview - click taking here to into buy the full publication without necessarily account the means used for implementation.
Circuit diagram including Terminal-function diagrams, "Schematic diagrams", etc. Diagram showing the implementation of the circuits of a a system, sub-station, installation, part, equipment, software, etc, depicting parts and connections by means of graphical symbols arranged to show the functions without necessarily taking into account physical sizes, shapes, or locations of the items.
Connection diagram including Connection diagrams, Unit connection diagrams, Interconnection diagrams, Terminal-connection diagrams, Cable diagrams, etc. Diagram showing or listing the connections of an installation or equipment. Installation diagram Installation drawing showing the connections between items. Network map Overview diagram showing a network on a map, for example generating or transforming stations and power lines, telecommunication equipment and transmission lines.
Rules for the application of the symbols are generally contained in IEC The following paragraphs contain a few of the basic application rules from this standard. Choice of symbols [top] In cases where there are alternative forms of graphical representation for one concept indicated e.
Some symbols have "general symbol" as part of the name. These symbols are usually the source for a whole group of more specific symbols. The general symbols are to be used in cases where the more specific ones are neither required nor desired.
Symbol size [top] The meaning of a symbol is defined by its shape and by its content. The size and line thickness do not affect the meaning.
The minimum size of a symbol shall be such that the rules for line thickness, spacing of lines, lettering, etc. Within these constraints, the symbols intended for installation diagrams and network maps may be enlarged or reduced to suit the scale of the plan or map.
The symbols in the database are shown on a grid pattern with a modulus M to specify symbol proportions. For readability the modulus shall be equal to or greater than the lettering height. In some cases, it may be necessary or advantageous to use different sizes of symbols: — — — — to to to to increase the number of inputs or outputs; facilitate the inclusion of additional information; emphasise certain aspects; and facilitate the use of symbol as a qualifying symbol.
When enlarged or reduced the general shape of the symbol should be maintained and, if practical, also the relative proportions. For detailed guidance of the design of symbols and their adaptation to the use in a CAD environment, please refer to the different parts of ISO and IEC This is a of preview - click[top] here to buy the full publication Orientation symbols Most symbols of IEC are designed for a signal flow from left to right.
This principle should also be maintained in all diagrams as a general rule and the symbols preferably shown as in the standard. In some cases it is necessary to deviate from the basic orientation of the symbols. Therefore the symbols may be turned or mirror-imaged if the meaning will not thereby be changed. In other cases it may be necessary to redesign the symbol to suite different orientations. Generally, it is not necessary to add symbols for terminals, brushes, etc.
In a few cases, the terminals are part of the symbol shown in the database and shall be shown also when applied in a diagram. How to create a new symbol from existing elements [top] When the graphical symbol required is not found in the database, it may be possible to create one from the existing ones. Pick the symbol for the basic concept and then combine it with one or more appropriate supplementary symbol. Supplementary symbols are: — primarily symbols explicitly depicted as "Qualifiers" in their application class, or, — principally, any other symbol in the database, if necessary suitably modified in size.
The supplementary symbols can be placed inside, outside or across the basic symbol. No simple rule can be given, since the placement to a high degree depends on the shapes of the symbols, available space in or around the basic symbol, etc. Do not overload the symbol. Limit the number of supplementary symbols to what is required to emphasise the wanted concept. For further guidance on the design of symbols, please refer to ISO and IEC Design of graphical symbols for use in the technical documentation of products - Part 1: Basic rules and Part 2: Specification for graphical symbols in a computer sensible form including graphical symbols for a reference library, and requirements for their interchange.
The database contains numerous examples on how combinations are done. A symbol created as a combination of already existing symbols and in line with the rules given in ISO and IEC is considered to be in line with the IEC standard.
How to process requests for new symbols [top] If there is a need for a symbol that cannot be satisfied with the already existing set of symbols or by combinations of these symbols it might be necessary to create a new one, and to get this internationally standardised. The description should preferably be accompanied with a proposal, including the graphics as the textual descriptions.
Use the information in the database as a model. This as is awell preview - click here to buy the full publication Your National Committee will then, after possible discussion and consultation, forward the proposal to the relevant Technical Committee in IEC: TC3 Information structures, documentation and graphical symbols.
The symbol will be initially entered into the database with the status: "Proposed". The proposal will then be quickly reviewed and evaluated by a Validation Team composed of representatives from the different National Committees, leading to a decision whether or not the proposal should be the subject for further work, and if the "normal" or an "extended" procedure should be used. In case of a negative decision the status of the proposed work will be changed to "Rejected" and the reason will be explained.
In the case of a positive decision the proposal will be given the appropriate technical form, and the status changed to "Draft". The proposal will then be subject to formal vote by the Validation Team and if accepted, the status will be changed to "Standard".
With this fully electronic procedure the processing time from the moment that the Technical Committee gets the proposal until the possible release should be less than 20 weeks in the case of the "normal" procedure. If the proposed graphical symbols are concerned with an entirely new technical area another approval mechanism is used, namely the "extended" procedure, which involves the National Committees directly.
In that case the processing time is approximately 56 - 74 weeks.