When working with drawings for the fabrication of electrical machinery, switching devices, electrical motors, electrical generators, and other “mechanical” elements associated with electrical equipment are all based on the same principles.

Because the complexity of modern electrical circuitry and technology a considerable amount of graphic symbols have been developed for describing the connection or function of the circuits. Those approved by the American National Standards Institute (ANSI) are published in” Graphic Symbols for Electrical and Electronic Diagrams.”

For any drawing or design intended to be reproduced, line thicknesses and letter sizes should be selected according to the amount of reduction or enlargement involved to te extend dictated by legibility requirements. A line of medium thickness is recommended for general use on electrical diagrams. A thin line may be used for brackets, leader lines, etc. When emphasis of special features such as main or transmission paths are essential, a line thickness sufficient to provide the desired contrast may be used. Line thickness and lettering will generally conform to the American National Standard.

As just stated symbols used for designs should conform to ANSI or to some other nationally approved standard. If no symbol is available, a special symbol may be placed if a explanatory note is attached to the drawing. It is recommended in ANSI that symbols be drawn roughly 1.5 times the size of the samples shown, provided the anticipated reduction is no greater than 2.5 to 1. Following these recommendations, circular tube envelopes will be about .88″ to 1.00″ in diameter and circular envelopes for semiconductors will be about .62″ to .75″ in diameter, although the envelope for semiconductors may be omitted if no confusion results. Some textbooks on this subject contain much more detailed recommendations about symbol sizes, and spacing arrangement than my website.

Switches and relays should generally be shown in the “normal” position, with no operating force or applied energy. If exceptions are necessary for switches that operate in several positions with no applied force, an explanatory note should describe the conditions of the electrical design.

In other Fields of technical drawing, abbreviations on electrical diagrams should conform to ANSI recommendations. When certain parts or components are naturally grouped as in separately obtained subassemblies or assembled components, such as relays, tuned circuit transformers, hermetically sealed units, and printed circuit boards, this grouping may be indicated by means of an enclosing dashed line “box” or by extra space from adjacent circuitry.

When working with and designing Electrical Diagrams you have to maintain the industry standards. CAD software programs have made the process of designing these complex electrical diagrams much easier while still maintaining the standards of ANSI. With the use of these computer programs the task of designing electrical schematics has been less time consuming and much more efficient. These programs include functions specifically for the design of electronic diagrams, and user-friendly tools that are easy to manage. To learn more about Electrical Engineering and CAD Design you should visit eLine Design LLC for their Free Resources on all Electrical Engineering topics.

Tags: Engineering, Lessons, Resources

Posted in CAD Lessons
Comments Off Posted by eLine Design