Schematics technique 3 : Return of the Can o' Worms

[TimothyMoulder]

How much detail do you go into in your schematics?

I've seen schematics where every termination is labelled, every cable line is explicitly identified, and every wire in between is marked with a unique ID number.

On the other extreme, I've seen schematics where there is a line between output and solenoid, marked with the wire number, and any number of cables and plugs are simply ignored.

Some people seem to think the higher level of detail is overkill. Others think the lowest level of detail isn't helpful.

What do you guys think?

TM

 

[rsdoran]

Jes an example, lets say you have Output O:2/15 (SLC) and number that wire 215 then it should stay 215 to its destination, if'n there are terminal blocks between where it starts and its end please reference them.

Output                TB2-15            TB4-15   
(2/15)------------------< <--------------< <-----------(SOLENOID)--:
          Wire#215           Wire#215         Wire#215

This may seem overly detailed but dang if it dont let ya know where something is or should be. Eliminates having to sift througn wires with tracer or ohmmeter and some secondary wire to verify you have the right wire.

Ya know some of us guys aint the sharpest knife in the drawer, we need pictures, pretty flashing lights, and tell us what wire it is and where its going and how it got thar.

 

[Sebastien]

In my company we take this approach:
1) The more info the better
2) My boss would be able to troubleshoot from the drawing
3) All the required information is on the drawing so troubleshooting is easy.

The result is about the same as what "rsdoran" wrote. Terminal block, wire color, labels, room location, panel number, rack name. It's all on the drawing.

We use different wire number for each section. Sometimes with the suffix "a" "b"...

For a solenoid, we would add the Watt rating if know (when the drawing is done). We would also indicate a comment like: "Energize to vent" or "Power to close". For inputs: "P<60 psi closed"

 

[Terry Woods]

Who the hell wrote (or drew) this ****!
(Knowing full-well it was me!)

Too much GOOD INFORMATION is a hell of a lot better than too little.

I kick myself in the A$$ everytime I find that I wrote a "Microsoft-type" description (words or drawing) - tons of info - but No "Picture"!

 

[Doug_Adam]

After arguments, accusations and the appliance of a big spiky club, my company settled on a drawing standard similar to what rsdoran explained.
Actually, everyone agreed from the start that this standard was needed. The grief came when we were working out a standard method of numbering that would cause no conflicts accross site.
Overall, The more detailed, the better.

There is, however, one detail that I find curious.
Whenever I get a machine from europe, it seems that a full third of the drawings seem to be blank except for an earth point symbol randomly located somwhere on the page. Has anyone also had the same experience? And does anyone know what these drawings are for?

Thanks,

Doug

 

[EagleElectric]

Just a thought

when it is your anniversary and you get called away from dinner and you have to go to work and its 15 degrees F outside with a 40 mile an hour wind and your RTU just went down and you have to troubleshoot the panel with a drawing that had no wire numbers or some that were duplicates of others.......Boy, your wife is gonna love this sob story.


Moral: The more you bleed in training the less you bleed in war.

 

[Sparky]

You decide

What is most important is "does this make sense". Also who is going to need/read this info. If you are the only person reading the scematic then who cares after a few years you know just about every I/O in the system. But then you hire some one else to ease some of your work load. Can they trouble shoot with what is in the schematic.
what ever you do or decide keep it the same. The hardest thing we deal with is when we have a new project by an outside contractor who programs the project and writes the schematic. Now we either rewrite the definitions or have no clue as to the number scheme they use for their wires and I/Os.

 

[seppoalanen]

Hi Doug, I'm from €.

I have done Projects to allmost anywhere, even NZ and US
but not to Australia.
I understand (guess) in US they use 'potential-point' labeling, so same potential point is the same in PLC-cubicle, terminal boxex etc.

Somewhere in €, Germany, North-€ they uses terminal numbers and
it can be diffrent in the same potential point. Terminal block ID can be the same than cable-ID (terminal block is for that cable in this case) and terminal numbers are numbers of the cable-cores (wires).

Other hand terminal numbers can be what ever without any logic, but
labeling must be done as terminal numbers and this is not enough, yuo like know where is the other end of the wire (other terminal, I/O-point etc.). Usually wire-labeles are not separetly market to Circuit drawings, you must guess by terminal numbers. Sometimes we don't use any labels in the wires, so if there are more than one wire in the terminal, you can't know other end addresses without extra work.

Many times our final customer give us their instructions and we try to do everything as customer likes. Some times there are instructions for fiel devices etc. what we must use, and some times there are equipment whose manyfacturing have ended since 1966, so please update your Instructions time to time. Some times it's wery hard to buy some eq. outside € if delivery time is short for us.
My mother tongue is finnish, so be patient with me.
-------------------------------------------------------------------
We don't need nuclear power plant, we can get electrity from socket outlets.

 

[BobB]

Basically we do not worry about terminal numbers lining up with anything. They are just terminals. However, wire numbers are a different kettle of fish. Use the same wire number all the way through the circuit.
THEN, we win the order to manufacture the control panel and someone else makes the main board. Bedlam takes over. The only way to get around this one is mark the main board terminal numbers on the control drawing as a cross refernce, if you can obtain drawings from the devils, and then the customer can track to the main board and use that drawing for trouble shooting the large beast.
banghead