Schematic Guidance

J

jdawson

New User
Location
Anaheim, CA
Occupation
Electrical Engineer I
Howdy all,

I graduated in May with a BSEE. I've recently got a job for a company that manufactures devices controlled by PLCs. Mostly just simple (on/off) fan motor control, light control, E-stops, button control, the odd sensor.

As far as I know I'm the only BSEE employed by the company. My boss and all of my coworkers are mechanicals. My predecessor was too, although more electrically inclined than some. Early on in my onboarding I was told by some of my coworkers to not take anything I learn here as the... right, or standard way to do things, compared to other companies.

Most of what I've been doing in the last few weeks has been rubber stamping schematics before production. Yeah, this product has slightly different outside dimensions but identical electrical components? Copy-paste the schematic from an old model, tag it with the new serial, ship it.

Now though, they're having me select components and design a control box for a new product. I need to draw the schematic for this.

I'm looking for good examples of drawn schematics of industrial control panels that I can compare my own drawings to. I'm also looking for general advice. Power Systems was one class two years ago and I had never touched a codebook until I started this job.

jdawson
 
If your are building control panels that will be Listed to standards like UL508A, then NFPA70, the NEC, will not help you as much as NFPA79, the standard for industrial machinery.

Neither of them contain much in the way of standards for schematics. You might want to look at some wiring diagrams from companies like Rockwell, or Schneider Electric. They used to have booklets for common starters and such.
 
First off, congrats on graduating and welcome to the field! My second job (~25 years ago) sounds a lot like what you're getting into, only that I was trying to break another programmer's logic in new and creative ways and writing some relatively simple PLC automation of my own.

As Jim says, you'll not find a whole lot in how to create schematics in the various codes and standards; those are going to tell you "For situation A, THHN is an acceptable wire type, SJ is not. Running through environment R requires EMT rather than LFMC. Emergency egress lighting requires N minutes of battery," and stuff like that. Companies will have their own methods for creating schematics (the one I was at just doodled with MS-Paint on WinXP, they were too small to afford AutoCAD), but symbols for things like fuses, motors, relays, and the like will be common among all, so make sure to learn those. On the plus side, it sounds like you'll be the one creating your company's standards, so the field's wide open when it comes to choosing what tools to use. If your designs are relatively simple and very cookie-cutter, Visio might be enough to get the job done. If you're getting into really crazy complex stuff, it might be worth looking into an AutoCAD subscription.
 
At one time mfgs had catalogs that had all sorts of wiring diagrams to pick & choose from.

I used The Constructor from CMH software to draw my own. Diagrams could be run in a simulation mode to prove operation.
AD also has PLC and HMI software that can be simulated. I would expect others to have similar.
 
jim dungar said:
the NEC, will not help you as much as NFPA79, the standard for industrial machinery.
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I'll give it a read then, thanks. They are going to have me submit stuff to UL later but I figure that's a question for them and their book.
ModbusMan said:
Companies will have their own methods for creating schematics
Click to expand...
That kinda answers my main question. I was worried there was some standard.
ptonsparky said:
I used The Constructor from CMH software to draw my own.
Click to expand...
This looks pretty cool, thanks, I'll have to mess around with the trial.
 
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