Drawing Symbols

[ettikudiappan]

I am currently specing a electrical and controls system for one of our suppliers. When specifying the standard to be used for the drawing sensors and solenoid valves, I realised that there were many standards to choose from. ISA, ANSI, IEC. Which one is best suited for control diagrams? Where can I get the symbols on the web, so that I can see how it looks like before I spec?

[Pierre]

<<Where can I get the symbols on the web>>

Simply do a search (like www.google.com) with the words CAD and symbols ... you will get tons of link.

I kinda like the mechanical engeneering sites... they do have many symbols files.

[Tom Jenkins]

Symbols vary slightly from industry to industry, and widely from drawing type to drawing type, at least here in the states. For example, for Process and Instrumentation Diagrams (generally the first drawing created in the process controls industry) the symbols established by the Instrument Society of America (ISA) (ISA-S5.1) are generally used, although in some industries the letter designations vary slightly. For panel wiring the symbols developed by the JIC (Joint Industry Conference) for switches, relays, etc. are used, but in Europe the symbols for many items vary slightly. For power and distribution (for example MCCs and switchgear) a whole different set of symbols are used for switches, transformers, etc. If pneumatic controls are part of the system, the National Fluid Power Association has a whole set of symbols that are used, but they are different than the ones used on the P&I Diagram! When it comes to the physical panel layout, here in the states we use third angle projection with the top view above the object, but in most of the world they use first angle projection with the top view below the object.

Confused? You should be, because it is in many ways a mess. However, history creates strange artifacts, and that is what is going on here.

What I suggest you do, after a tall cold beer and surfing the web per the above suggestion, is to get a good set of "similar too" drawings. These will be a clean looking set of drawings from a past project created by someone you respect. Use these as the guideline for symbols, nomenclature, and format. Drawing symbols and technique don't have to "right", they just have to be consistent. If you use symbols that are per national standards but aren't familiar to your local contractor you will have problems. If you use symbols normal for your area you will communicate your design intent clearly. And, after all, clear and precise communication is the objective of creating the drawing in the first place!

[Goody]

These days we all read drawings from all over the world and the symbols vary widely. I like a drawing where the symbol looks just like what it is representing. It is probably advisable to print a bibliography of the symbols somewhere and then there can be no ambiguety.

[chakorules]

I think most people might still be using the JIC standard even though it's kinda dead. (JIC standard of a snap .125 inch scale)

Do you have AutoCad 2000? If so, you can download a FREE addon menu symbol libray at this place:

http://www.mrplc.com/cgi-bin/code/filedisplay.cgi?category=misc

Scroll down to:
AutoCad 2000 JIC Electrical Symbols Menu Add-On 1.0

Download that menu pack. Works like a champ.

If you want to make this into an IEC standard, just scale the symbols to a metric scale. You'll be fine.

Good luck.

[hordener]

I normally use the IEC standard and have had no complaints.

hordener.

[Platootod]

Let try some software name The constructor from koldwater.com,or Automation Studio fro m Famic
You can select standard (IEC or ..) to make control diagram with
several symbols.

Platootod

[shooter]

ask the supplier what he is used to. If you can live with his symbols fine do it.
however i would recommend to use one set of symbols all over the project. And i would like to give you my symbols, no problem just ask me.