Hello Community, looking for a decent freeware electrical CAD I crossed these pages.
in general speaking there is very little on the internet making up a decent freeware electrical CAD.
Hence the Idea tossed around in this forum, on designing something based on a popular CAD package seems to me to be great.
My background; automation engineering on various levels of management. From junior engr. to senior mgt. my first contact with Electrical-CAD was in the early 90’s on a rothring E-Cad.
Now to the point, IMHO;
In this discussion there are two important things to be differentiated
• Electronic Engineering (Idea, circuits, PCB design, PCB manufacturing …)
• Electrical Engineering: (set of sensors and actors attached to something, e.g. house, machine, plant etc.)
• Automotive electrical drawings again are an other cattle of fish. Not further mentioned here.
Above results in two completely different needs.
For the electronics division, the circuit drawing is used for PCB routing, photolitho (or whatever PCB printing technique).
The electrical division will draw up schematic diagrams, of which terminal list, cable list and parts list are generated. Professional tools are also capable to lay out the control cubicle with the components defined in the schematic diagram and component data base. An important parameter is the geographical allocation of sub-cubicles, sensors and actors belonging to the control being linked to the “mother”cubicle. (Hence the suggested routing on cable trays is a very desirable feature)
Having been working on all continets (less Antartica
) I also learned that there is not an unique approach to drawing standards. The systems might be divided up in the American drawing standards and European drawing standards. Where in the US several square feet large drawings had been used, the Europeans use since many decades drawings of A4 size, in the old days sometimes multiple A4 (e.g.7xA4, all one paper). The main reason for A4 was easy handling of the schematic drawings in a book size. (Still today, many wiring workshops work on paper copie, though big Screens are applied in big outfits.)
The last comment does bring an idea to me, how to have a function where the workshop can thick off on a screen the wired wires in a soft copy of the schematics. This would open a new world to CAD/CAM in the world of wiring control cubicles. (well at least to my antiquated knowledge).
In this forum a lot has been kicked around on symbols. There are the DIN standards (most also EN / IEC standards ) on:
• Symbols (
https://std.iec.ch/iec60617 )
• Codes (abbreviations) for actors and sensors
https://de.wikipedia.org/wiki/Betriebsm ... rotechnik)
• Geographical allocation (EN 81346-2,
https://de.wikipedia.org/wiki/Betriebsm ... rotechnik) )
• Drawing setups
In principal there are only small deviations from the standards allowed as the el-schematics are part of the legal demanded documentation for EC conformty declaration.
From personal experience, depending on the location on this nice world, the symbols change slightly. A symbol editor would be probably a must.
As in many electrical schematics two symbols exist (mother symbol and daughter symbols, e.g. on a relay the coil being the “mother symbol” and the contact actuated by this coil would be one of the “daughter symbols”( one to many /1:m relation) it would be important to have a automatic update function if the name of the “mother symbol” changes.
Automatic naming according to the drawing path is standard.
The same applies for the reference table displayed at the drawing location of the mother symbol. each contact location (page and path)
One of the big deficiencies of Visio-CAD based technology compared to a desired free-cad; the first type has difficulties to move connections (end point of a wire) if the symbol is moved. It needs always to be done in two steps, move symbol (with one attached connection moving also) and the second connection has to be adjusted manually to be straight vertical up to the bars) , by experience a big source of capital mistakes.
Some nice videos on a usable, but with deficiencies littered commercial product:
https://www.youtube.com/watch?v=ZqHKKhzrrlA
Since I do not have a clue how to program such a thing, I am no help on the doings. If you need input on the specification ant further information on the workflow to create an electrical schematic diagram I am willing to participate with my share.
KR Conrad