Calculations in the modern digital age

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junkhound

junkhound

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Renton, WA
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EE, power electronics specialty
Just curious what others who need to do complex system analysis are doing:

Has anyone, other than helping a grandkid with homework, actually needed to solve a differential equation or use calculus in the last 10 years? 60 years ago pocos had big analog computer setups for system analysis, am not aware of any of those still in existence?

Think the last I actually did a differential equation solution for a dynamic electrical system response solution was 45 years ago, from then till late 80's still used Laplace; after mid-late 80's have pretty much only used FEA methods and programs. There are a few simple structural and thermal problem still use just simple math.
Calculus similar time frame.

A simple voltage drop question thread brought this to mind. A string of constant current loads is simple addition, constant power loads a bit more complicated, and 3 phase with PF a bit more. Once into RLC circuits with active elements then simple math becomes exceedingly cumbersome even with spreadsheet.

For a quick answer to the poster on the volt drop question it took only 2 minutes to put the question into PSpice and get an answer for constant power loads; would have had to solve 5 quadratic equations for the constant power load situation. The constant current string case one can do in one's head.

In reflecting realize I've forgotten how to even setup a differential equation circuit analysis solution without recourse to 55 YO textbooks, too easy to use Matlab or PSpice for exact answers.


What are your go-to FEA programs? -- mine are Orcad PSpice for circuits and Maxwell 3D for thermal, fields, electrostatics, and combined systems.
 
Interesting, 160+ views and no comments,

Must be like an old electrician told me "calculations, we don't do no stinkin' calculations, that's for the eng to put on ht drawing"
 
junkhound said:
Interesting, 160+ views and no comments,

Must be like an old electrician told me "calculations, we don't do no stinkin' calculations, that's for the eng to put on ht drawing"
Click to expand...

Hold On. Have some patience. I was trying to remember what a differential equation was so I could be honest about it. I’m sure there were at least another 120 doing the same.
 
Most electrical analysis can be accomplished with linear methods. Gets us close enough to construct buildings. The only complex software we use is SKM. At the end of the day, SKM analyzes linear systems, but with way too many degrees of freedom to practically do on a spreadsheet, for example.

Manufacturers, on the other hand, use modelling software that absolutely takes advantage of those high order maths to create their transformers, starters, drives, led drivers, motors, generators, etc. An exception would be a company like Lutron. A simple solid state wall dimmer can probably be solved by hand in a few minutes, granted someone remembered how to setup the equations.

just a consulting engineer's 2 cents. :)
 
I agree with drktmplr12. For consulting engineers and electrical contractors, the BSEE curriculum is overkill.

My degree is in general engineering - not BSEE. I learned just enough electrical to pass the PE exam - which turns out to be way more than I've ever needed to produce code-compliant designs for the last 30 years.

Maybe If I knew how to do complex systems analysis I'd be getting a different level of commissions, but in my experience, the electrical construction field requires knowledge that's broad, not deep.
 
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