3D Substation Design Explained

By George Flew, P.E.

Since Thomas Edison designed his Pearl Street Station in 1882, engineers have had to contend with the presentation of their design on paper – the very essence of 2D space. Edison’s answer to the need for a 3D presentation was to prepare an artistic rendition of the space.

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Today, we have one advantage that Edison lacked – the computer. Engineers are now free to let their visions soar, to investigate options that make facilities more economic, more dependable and safer to operate. This can be achieved utilizing the power of 3D design. But to do this, a Toolbox of building blocks and software is required. It can be a very time consuming task to develop such a Toolbox.

Figure 1. Artist rendition of Edison’s Pearl Street Station (Copyright unknown)

History of AutoCAD 3D

The use of Computer Aided Design (CAD) in the preparation of substation design drawings goes back to the 70s and 80s. These early systems generally utilized main-frame computers and dedicated workstations putting the cost out of reach for the average Utility system. Autodesk®, then based in Mill Valley, CA, released PC-based 2D AutoCAD 1.0 in December, 1982. Support of 3D, even rudimentary, would not arrive until 1985. The following chronicles AutoCAD’s development of 3D.

1985 – Version 2.1 introduced 3D Level 1 which included 3D wireframe visualization.
1987 – Version 2.6 added 3D Level 2 with 3D Line, 3D Face and 3D Plot capabilities.
1994 – Release 13 included 3D solid modeling functions based on the ACIS 3D kernel.
2007 – Release of AutoCAD 2007 in 2006 introduced the SectionPlane command which allowed for the generation of section objects acting as cutting planes through 3D objects.
2009 – AutoCAD 2010 introduced the SectionPlaneToBlock command which saves selected section planes as 2D or 3D blocks or as drawings.

With AutoCAD 2009, all of the necessary drawing tools were available for the efficient production of 3D Substation Design.

In 1999, Autodesk released Inventor® (a non-AutoCAD product) which has become their flagship application for “professional-grade 3D mechanical design, documentation, and product simulation tools”. It has been used extensively for 3D substation design. However, with the annual prescription rate for Inventor around $2,000 per year per user, it is not economically feasible for many smaller utilities. Alternately, many smaller utilities do currently utilize AutoCAD for Work Order production and/or mapping. And, with the right tools, it has all of the features necessary to be an economical and efficient method of producing quality 3D design drawings.

Substation Design

A complete substation design project typically consists of three major tasks as follows:

1. Structure design – This involves the physical layout of all structures and appurtenances. It consists of a Plan View and a number of Section Views (or Elevations) that convey the layout of the substation to the substation material packager. From this all of the material required to construct the substation can be determined. This represents 30%-60% of the design time.

2. Relaying and Control design – This includes relays, housing, wiring and conduits required to interconnect the various equipment. This requires physical drawings as well as circuit, schematic and wiring diagrams.

3. Specifications and contract documents – These are the documents required to procure the material and employ a contractor to construct the substation.

Substation design is commonly accomplished in one of two methods. The design can be achieved using staff personnel or a design consultant can be retained. In many instances, a consultant is retained because either the Utility’s staff does not have the expertise or, more often, they do not have the time. The consultant fee for the preparation of a complete substation design for even a modest substation can easily range from $75,000 to $200,000.

While a Utility may not have the personnel to accomplish all of the design tasks, it is possible to undertake the Structure design and cut the total consultant fee by 30%-60% or more. The key to this is to be able to efficiently create the physical structure layout. This is where 3D design is a major advantage.

Figure 2. Plan View with Section Lines

2D vs 3D

In substation design, there are several major steps that must be taken to develop the Plan and Section (Elevation) drawings. These are detailed in Table 1.

Figure 3 –Typical Elevation View with Dimensions, Bus Labels and Bubbles

In 2D design, if any modifications are made to the Plan View, one or more of the Elevations must be checked and possibly modified. Likewise, changes to the Elevations may result in modifications to the Plan View. And in all cases, conflicts must again be reviewed and resolved. And the BOM will need to be reviewed and possibly updated.

However, changes made to the 3D Plan View can easily be reflected in the Elevation views using AutoCAD by modifying the Sections and regenerating the elevations with the SectionPlanetoBlock command. If necessary, the BOM can be easily regenerated.

Benefits of 3D over 2D Design

There are several benefits to utilizing a 3D approach to design.

The design cycle is reduced. This is crucial to the justification of utilizing staff personnel for this task. The substation design is prepared completely in the Plan View utilizing a Toolbox of 3D parts and software applications. All Elevation views are then generated from the Plan View. Changes to the design on the Plan level are easily reflected in the Elevations with minimal time expended. The results are fewer design errors encountered during construction.

Construction costs are reduced. The more accurate design inherent in the 3D process results in fewer conflicts, fewer errors during construction and fewer Change Orders in the construction phase. Additionally, by presenting a perspective view, the contractor can more easily interpret the drawings.

Total project cycle cost is reduced. Overall project cost is reduced as a result of the reduced design cycle and construction cost savings.

And operational safety is increased. 3D design allows the engineer to check for adequate clearances as the design progresses not only for bus and structures but also for the operation of equipment such as switches and fuses.

Figure 4. 3D Substation perspective view

There can be one major drawback to 3D drawings. The development of 3D blocks and their manipulation in the 3D space can be very tedious.

When initially delving into 3D design, the first problem that becomes evident is the need for 3D blocks that accurately represent the various pieces and parts that go into the substation. This requires research of the numerous manufacturers of the many parts involved and the best manner in which to present them.

Once this is overcome and the structures and equipment are placed in the drawing, then the electrical interconnections must be made. This requires the placement of bus and jumpers that not only do not lie in the same physical plane, but often lie in planes that are skewed from each other. It is at this point that the engineer may reconsider the decision to design in 3D.

The solution is a third party system that can provide pre-defined substation blocks and applications that greatly simplify the total process. One such system is the 3DToolbox offered by the3DUtility.

The 3DToolbox

The 3DToolbox consists of 3D AutoCAD blocks (referred to as Units) and software applications that empower the Design Engineer to create Structure design drawings suitable for the procurement of material and contractors. The applications are built on AutoLisp, an intrinsic AutoCAD programming language and Microsoft® Visual Basic for Applications (VBA) for AutoCAD. VBA is distributed by Autodesk for free and is easily integrated with AutoCAD for all supported releases.

The 3DToolbox utilizes Microsoft® Excel for reporting of the Bill of Materials. However, output to .CSV file format is also supported. No other software application is required for the operation of the 3DToolbox.

The 3DToolbox contains over 600 3D Units in the following folders:

Condulets – Used for control conduits and low voltage circuits.
Connectors – Bus supports, couplers, stud connectors, tees and terminals for tube and conductor bus.
Equipment - Lightning Arrestors, Bushings, CTs, VTs, Lighting, etc.
Insulators - Standard TR as well as High Strength, Extra High Strength and polymer, 15kV thru 230k.
Major Equipment - Breakers, Circuit Switchers, Power Transformers and Switchgear Houses, 15kV thru 161kV.
Structures - Switch and Bus supports, Breaker and Terminal structures.
Transmission – Transmission pole line hardware including fittings, insulators, and conductor clamps, etc.
Distribution – Distribution pole line hardware including fittings, insulators, crossarms, conductor deadends, etc.

Figure 5. Connector Units

In addition to individual Units, Units can be nested within other Units and blocks to form Assemblies. Assemblies can be placed in a single operation saving the Engineer considerable time dealing with minute details. The following are examples of Assemblies:

Breaker Assembly – contains Structures, Insulators, Connectors, Busses and Jumpers, Switches and Breakers.
Metering Assembly – contains Structures, Insulators, Connectors, CTs, VTs, Meter Cabinet with Condulets and conduit.
Switch Structure Assembly –a Structure complete with Switches, switch operator and grounding pad.
Using the 3DToolbox Units, the system is easily extensible by creating additional Assemblies specific to each Utility and could easily be customized from the 3DToolbox as required.

Figure 6. Units & Assemblies insert form

In addition to the Units and Assemblies, a number of software applications are provided to simplify the drawing preparation process including:

Unit Insert Form – Provides a simplified method for inserting Units into the drawing and manipulating their orientation. This is a VBA app.
Jumpers – Six routines are provided that cover all jumper connection configurations including - connector to connector, multiple connectors and connections between busses and between busses and equipment. These apps simplify one of the most complex tasks since the manipulation of jumpers in 3D space, often not linear in nature, can be quite time consuming. These are AutoLisp apps.
Bus creation – One of the advantages of 3D is the visual aspect. Bus creation tools simplify the production of pipe, angle, flat and conductor bus. These are AutoLisp apps.
Section & Elevation creation – Simplifies the AutoCAD Section and SectionPlaneToBlock commands.
Bill of Material (BOM) – A major advantage of 3D is that the Plan drawing includes all of the parts and pieces necessary to construct the substation. This provides an accurate count of all of the Connectors, Equipment, Switches, Busses, etc. required to construct the substation. This is a very powerful tool to assure that the substation packager’s list of provided material is accurate thus alleviating delays due to material delivery. This is a VBA app.
Miscellaneous applications for the manipulation of blocks, design checks and display of drawings.

Design of substations in 3D has been available for many years. However, the cost associated with the specialized software and training has left it out of reach of many smaller utilities. With the advent of systems such as the 3DToolbox, any utility that currently uses AutoCAD or any of the AutoCAD compatible programs (such as BricsCAD®) can enter the 3D arena with little cost. And the potential savings are considerable.

The 3DToolbox was developed by George Flew, PE. He entered the CAD substation design field in 1982 with Release 1.2 of AutoCAD when he presented it to his employer, Allen & Hoshall, Inc. He spent his career in the Public Utility sector designing substations, transmission and distribution systems and system planning. Since retiring in 2017 as the VP of Engineering for Jackson Energy Authority, Jackson, TN, he has devoted over a man-year developing the 3DToobox. After 43 years of memorable and dedicated work in the Public Utility field, he has release the entire 3DToolbox free of charge to any public utility entity.

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