Electrical control system graphics, symbols, and drawing principles

Sep 05, 2023

一     Electrical diagram and classification

Electrical diagrams are technical language used to illustrate the composition of circuits, the operating principles of components, electrical characteristics, and installation, debugging, maintenance, and use in electrical systems or equipment.

Electrical diagrams can be divided into three types according to their purpose:

Electrical schematic diagram: According to the nature of the circuit, the component symbols, wiring, and installation positions are arranged in the same plane. This diagram can clearly represent the principle of the circuit, but reading this diagram is more troublesome.

Electrical installation diagram: A drawing used to represent the relative position, size, installation method, etc. of electrical equipment and equipment.

Electrical system diagram: A drawing that represents the composition and connection method of the entire electrical system using graphical and textual symbols.

Electrical diagrams can be divided into seven types:

Circuit diagram: Use symbols and wiring to represent the working principle and composition of a circuit.

Outline drawing: used to represent the external shape and installation position of electrical equipment.

Layout diagram: used to represent the positional relationship of internal components of electrical equipment.

Wiring diagram: used to represent the wiring method of electrical equipment.

Installation diagram: used to represent the installation method of electrical equipment.

System diagram: Use graphic and textual symbols to represent the composition and connection mode of the entire electrical system.

Terminal diagram: used to represent the type and connection method of terminal blocks.

二  Electrical graphical symbols

Electrical graphical symbols are a type of graphical symbol used to represent electrical components and circuits on drawings. It is a type of electrical technical language that consists of textual and graphical symbols.

Text symbols are short characters or letters used to represent component names, states, action characteristics, etc. They are divided into basic text symbols and auxiliary text symbols. Basic textual symbols include single letter symbols and double letter symbols. Single letter symbols are abbreviated according to the first letter of an English word, while double letter symbols consist of a letter representing a type and a letter representing a specific function. Auxiliary text symbols are used to represent the model, specification, size, etc. of components, consisting of a letter representing quantity and a letter representing unit.

A graphic symbol is a type of graphic used to represent the appearance and action characteristics of electrical components and circuits on a drawing, which is divided into basic graphic symbols and auxiliary graphic symbols. The basic graphical symbol is a simple figure drawn according to the outline of the component, such as a resistor with a straight line, electrodes at both ends, and a resistor body in the middle. Auxiliary graphic symbols are added to supplement information on the actions, characteristics, and other aspects of components. For example, the graphic symbol of a diode is a straight line, with electrodes at both ends and a broken line in the middle, indicating the conduction and cut-off states of the diode

三  Principles for drawing electrical diagrams

The layout in the drawing must comply with national norms and standards, as well as drafting standards.

The annotations in the drawing must be clear and clear, including textual symbols, graphical symbols, technical parameters, etc.

The proportion of the drawings in the pattern must be accurate and in line with the actual situation.

The text and numbers in the pattern must be clear and easy to read, and the font should be standardized.

The lines in the pattern should be clear, of moderate thickness, and should not overlap or cross.

The title block in the drawing must include information such as the drawing name, drawing number, and drawing date.

The legends in the pattern must be clear and clearly labeled, in accordance with national norms and standards.

The annotations in the drawing must be accurate and free from omissions or errors.

The format of the drawings in the drawings must be standardized and comply with national norms and standards.

The technical requirements in the drawings must be clear and in line with the actual situation.

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