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How to read and understand an Electrical Schematic

Article by Joseph Lyon created/updated May 22, 2018

Ever wonder what’s behind the walls at home or researched how an electrical device works? Maybe you want to fix something that runs on electricity? At first glance an electrical schematic may come across as a confusing cluster of multicoloured lines and symbols of various shapes and sizes, which can be true, however they are much more than that.

Three-phase power distribution for a packaging line

Three-phase power distribution for a packaging line

An electrical schematic is a logical representation of the physical connections and layout of an electric circuit. A well documented schematic outlines the functionality of an electric circuit and provides the basis for assembly and troubleshooting of a system. A schematic can contain few or many symbols and connections and is normally read from left to right, top to bottom.

Symbols

Symbols are quite literally the building blocks to any electrical schematic. Symbols are a pictorial representation of the electrical component and usually display their respective connection points. The two most common standards for electrical design symbols are ANSI and IEC.

Common electrical schematic symbols

Common electrical schematic symbols

Device Tags

Marks and tags serve as an identifier to each electrical component on the schematic. They usually begin with a few letters followed by their assigned order number. Marks help operators distinguish between many of the same object.

Device tag of a motor

Device tag of a motor

Attributes

Attributes provide a detailed description of an electronic component beside its symbol. In SOLIDWORKS Electrical, attributes are variables directly linked to the manufacture part library, allowing values to be displayed or hidden as needed. The manufacturer and reference part number are commonly displayed symbol attributes. Attribute information is usually then populated on a Bill of Materials (BOM) or list of parts required to make the system.

Wires

Wires create connections and join components together, completing a circuit. The colour of a wire is usually indicative of its purpose. For example, green wires in a schematic often indicate the connection is going to ground.

Three phase wiring

Three phase wiring

Wire Labels

Components, wires and cables are assigned: labels, tags, marks or numbers to assist in traceability and allow for systematic troubleshooting of the design. A typical tagging scheme may include combinations of: device id, wire type, page number, row number, wire size and order.

Title Block

A title block is the border and text of the drawing that describes the project and current sheet. Common information displayed in a title block are: project name, company name, job number, company logo, title, author, sheet number, approvals and page scale.

ANSI Size B Title block

Once you know how to read an electrical schematic, the next step is to design your own. There always exists the method of brute force drafting and then there are intelligent tools to bring your designs to fruition quicker. In SOLIDWORKS Electrical, complex schematics can be created in a matter of minutes and portions of the circuit copied and saved for re-use. SOLIDWORKS Electrical comes pre-packaged with device libraries containing thousands of symbols, 2D footprints and manufacturer parts along with a variety of power, control, hydraulic and pneumatic wire styles to suit any electrical design. The best part is all the built-in tools and library data can be fully configured as necessary to adhere to industry and company standards.

See if making the switch from DraftSight to SOLIDWORKS Electrical is the right move for your electrical engineering team.

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Joseph Lyon

Joseph is on a twelve month internship with Javelin Technologies and studies mechanical engineering with a mechatronics specialization at Ryerson University.

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