Electrical Modeling vs. Manual Drafting

As an applications engineer I often find myself having to explain to a potential customer the difference between electrical modeling and manual drafting.  Showing the value of this difference is oftentimes a challenge not only due to the difference in technology but also the change in the culture required to move from one to the other.

As I begin to work with a new account one of the first steps is to understand their current design process.  While we are sure our tools can help the account we want to be careful to consider the parts of their current process that work.  We do not want the customer to take a step backwards by adopting our tools.

I often come across customers who use anything from paper napkins to mechanical drafting tools to define their electrical systems.  These tools and processes have a few advantages for the group or organization creating the drawings:

1. Easy to train and use.  Almost anyone can pick the tool up (or the pencil in some cases) and start creating drawings right away.
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2. Easy to create drafting standards.  Because these tools are free form without an underlying model anything can be drawn in any shape or format the organization desires.
3. Easy to purchase.  These tools are typically very cheap as they are simply drafting tools.

There are many disadvantages I see to using these manual methods - I will list a few of my favorites:

1. Static data.  Because the data that is being “drawn” is nothing more than a picture no downstream systems can consume it.  This results in human data entry and interpretation error when the same data is entered multiple times into various systems.
2. Compliance with corporate standards.  Because drafting tools allow user’s to draw without constraint it is difficult to enforce drawing compliance across the enterprise.
3. Data validation.  There is often no method to enforce design rules and constraints with drafting packages.  How do we know the wires fit the contacts (terminals)?  How can we be sure the user has selected the correct terminals for a certain wire/connector combination?  How can we be sure two inline connector pairs will actually mate?

Many company’s I work with have created a “throw it over the wall” culture - one group creates static drawings that are then sent to another group for consumption.  This group then must interpret these drawings, by hand and most often enter the information into yet another drafting tool or perhaps a spreadsheet or database.  I have seen company’s that do this three or four times and they readily admit many of their errors stem from data entry mistakes - the same data is entered and interpreted by hand several times.  With no electronic method to validate the data many hours must be spent using pen and paper to validate the designs from start to finish.

Enter electrical modeling and Capital Harness Systems (CHS).  As I was a systems and harness designer for automotive electrical systems prior to coming to work for Mentor Graphics I understand the flow of electrical data in an organization.  With CHS you can capture electrical connectivity, validate that it is correct and without entering the information again propogate it to the Harness Design activity, Procurement or any other area that needs to consume the data.  A few of the many advantages I see in electrical modeling over manual drafting are as follows:

1. The model can be electronically validated.  Because we are not simply drawing lines and boxes as with the manual drafting tool the content can be validated electronically.
2. Rules based design.  Because CHS was create specifically for electrical systems and harness design there are many rules and constraints one can apply to the design to automate common tasks such as wire sizing and component part selection.
3. Electronic data propagation.  Because CHS data resides in a database there is not longer any need to hand enter data into various systems upcoming completion of the connectivity drawings.  The drawings a designer or engineer creates in CHS are simply an extension of the underlying data in the database.
4. Drawing standards compliance.  CHS has a very sophisticated styling engine that allows company’s to create a drafting standard and apply this standard to any model that has been created.  User’s can focus on creating the point to point content, CHS will then ensure the style of the drawing is correct.

When I was working as a systems engineer we did not have tools this sophisticated.  We spent a good amount of time validating that our wiring schematics matched our harness form-boards manually - circuit by circuit.  With tools such as CHS engineer’s can get back to doing what they do best - engineering and worry less about drafting and drawing pictures that no one else can use.