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The Modular Concept: Substation design naturally lends itself to a modular design approach, even when companies existing engineering standards do not necessarily align with this methodology a change in perspective can achieve desirable results.

As mentioned in previous articles, I opted for a modular approach to the development of 3D Cad parts, subassemblies and top level assemblies. This is how it works:


This area is the 44kV area incorporating a structural framework on which we have various electrical components comprising insulators, circuit breakers, switches, busbars etc. The existing 2D engineering standard drawings were elevations spanning 5 or more gridlines for each grid; which for the 2D world worked okay but not conducive to working in 3D.

The company had attempted to simply reproduce these engineering 2D standards as 3D models with the top level assembly comprising the entire elevation at each gridline which did not work out too well. The notion of simply converting existing 2D data to 3D models without considering opportunities for improvement is a typical approach for most companies. To me this was not ideal thus the reasons for researching their historical projects from which I was able to devise the eventual modular solution.

When I researched the past projects I recognized that some areas for every project virtually stayed the same whereas other areas changed considerably according to the design requirements. It transpired that these same areas had only 2 or 3 variations typically used to satisfy the design needs for those last 9 projects thus providing the data for a modular solution.

Shown here is the evolved modular approach. The company 2d engineering standards were designated as Work Packages that represented the specific areas of a typical sub station design. For the purpose of relating the new methods with existing, we elected to retain the Work package designations.


For each area, we identified logical assembly modules as shown below. The example shown here is for the structural framework showing the different modules and their locations. I had already devised a numbering system for identifying these assemblies and parts. A similar approach was devised for the other work packages.



The Electrical content was then created as separate modules based on the structural assemblies as shown above. For each area, there was a minimum of one Electrical module for each grid quadrant that may be subject to variation according to historical project data and therefore we may have 2 or 3 different configurations covering the most common assemblies which we then built and maintained in a 3D standard library.

The 3D library comprised a hierarchy that replicated the various ID categories and class codes from the existing ERP catalog system.

Cad Library

So we now have a library of 3D modules (sub assemblies) for the 44kV area that contains units representing the most common configurations of Electrical/Structural units based on historical data that are likely to be used for the majority of future projects. Essentially a plug ‘n’ play arrangement where we simply selected the appropriate modules from the library and drop them into the project. Today the ability to copy entire assemblies is greatly enhanced with the latest versions of Inventor.

By researching historical projects and identifying consistency and common features in the design of various projects we can devise a modeling regime that incorporates these observations in a modular context thus saving considerable time for future projects.

We also paid attention to the model format and description content for the purposes of creating a BOM similar to the following (early example). This was later improved to be more consistent with descriptions and model/drawing numbering.


The other main advantage to working with a modular system like this relates to Procurement. I developed a database specifically for the purpose of tracking materials used by the Procurement guys to manage costs even as the Substation design was in development without requiring access to the actual Cad system.

The database was an indexed based design which the Microsoft guys went to great effort to advise could not be done; I did it anyway and it worked fine. This gave us the ability to interrogate model material lists and track costs at any stage of the project without annoying the engineers for constant updates. Effectively a useful procurement and project management tool. For more details on how this worked refer to my later post.