Single Line Diagrams or SLD drawings are a useful tool for visualizing and communicating the layout and interconnectivity of complex electrical and industrial control systems. However, creating sld drawings that are detailed yet remain clear and informative can be a challenge when dealing with highly interconnected systems. This blog post will provide some tips and best practices for creating sld drawings that effectively convey the necessary information while maintaining clarity even with complex designs.
Simplify Where Possible
One of the keys to creating readable sld drawings is to simplify the design where logical and omit unnecessary detail. For example, if multiple components have identical or near identical connections, consider combining them onto a single drawing element rather than drawing each one separately. Similarly, common subsystems or circuits that don’t impact the overall connectivity can sometimes be represented as black boxes rather than fully drawn out. The goal is to focus on the core information needed while removing unnecessary visual clutter.
Use Layers and Grouping Strategically
Taking advantage of drawing layers and grouping elements is extremely helpful for complexity management. Major subsystems or circuits can be placed on their own layers and turned on/off as needed. Similarly, related components can be grouped so they behave as a single entity that can be easily manipulated. This allows breaking the drawing down into more manageable sections without losing the overall context. It’s also good practice to use different layers or colors to distinguish different voltage levels, circuits, fluid/gas lines etc.
Headings and Sections
Providing clear headings and sections within the drawing helps users navigate and comprehend a complex sld drawing. Major sections can each be on their own drawing sheet or placed in well defined areas. Consider including a table of contents style index to call out the sections. Sections should be logically grouped based on location, function or other organizational schema. Consistent heading styles and numbering schemes aid readability.
Use of Symbols and Icons
Utilizing standard symbols and icons for common components, rather than just simple shapes, adds clarity and conveys meaning at a glance. For example, using an iconic representation for things like pumps, valves, instruments etc rather than just circles or boxes. Stick to consistent, recognizable symbology throughout. Consider including a legend calling out any non-standard or customized symbols used.
Appropriate Annotation
While too much annotation can clutter a drawing, key labeling is important for disambiguation and contextual clues. At a minimum, all terminals and connection points of major equipment should be labeled. Additional annotation explaining flow directions, interconnections or complex sections can aid comprehension. Keep annotation styles consistent and place it strategically to not block important detail. Use additional text boxes, balloons or leader lines as needed.
Hierarchical Design
Whenever possible, design sld drawings with a clear hierarchy and flow. Place components, subsystems and related elements near each other in a logical, sequential arrangement. Visually group related items and use consistent layout rules to make implicit relationships obvious even in complex designs. The overall flow should be intuitive and visually guide the eye in a sensible order.
Appropriate Scale and Layout
Proper scale and whitespace management is important for legibility even with many elements. Leave generous space between unrelated groups and avoid overcrowding similar components right next to each other. Consider using different line weights, dashed vs. solid lines etc. to emphasize important interconnects over less critical ones. Provide enough overall drawing area that elements are clearly distinguishable at a reasonable zoom level.
Identify Revision History
It’s common for sld drawings to undergo many revisions over time as systems evolve. To aid traceability and incorporate changes, include a revision block noting key changes between versions. This might include a revision table listing dates and high level descriptions of updates. Numbering revisions in the title block ensures the correct documentation is referenced. Revision histories allow maintaining accurate as-built documentation over the system lifecycle.
Connections and Terminations
Clearly depicting how components interconnect is a core function of sld drawings. Consistently indicate connections using symbolic lines, numbered terminations, line identifiers or other conventions. For complex termination areas, consider including an enlarged detail view for legibility. Differentiate between physical interconnections like cable runs vs. abstract interconnects like data/signal links. Proper representation of connects and terminations is paramount to the drawing’s usefulness.
Use of Best Practices
Following standard industry practices and guidelines ensures sld drawings are compatible with how facilities engineers expect to interpret them. Refer to sources like ISA-5.1 for general instrumentation drawing standards or specific manufacturer symbologies. Consistency with other onsite documentation like P&IDs and installation drawings is also important. When in doubt, seek input from local engineering subject matter experts to align with expected site practices.
Conclusion
While sld drawings alone can’t capture every detail, following good principles for structure, hierarchy, clarity and abstraction allows effectively representing even highly complex systems. With practice and experience, it becomes easier to identify opportunities for simplification without losing critical information. The focus should be on enhancing comprehension and usability for the intended audience. By implementing tips like those discussed here, sld drawings can serve as valuable visualization and communication tools.