Hi.
I am drafting a schematic/wiring diagram for a large electrical panel.
At present it has the components - contactors, controllers etc showing numbered wires. None of the wires of "nets" are joined up on the drawing. This makes it difficult to grasp how the components relate to each other.

I would appreciate suggestion about what documentation methods are possible for such a circuit. I could show the connections as lines (coloured where possible), but that would be a great big rat's nest and still difficult to read.

Ease of editing and revision for myself and others in the future is a factor.

If possible I would like to avoid introducing a sophisticated new graphics software package because me and my colleagues would have to learn it, but there might be software that lends itself to the job.

I would appreciate your advice.

 

Do you have NFPA79? Electrical wiring for control panels. Shows Both logic and panel layout etc.
It would be a starting point , in NA the ladder logic rungs proceeds across from left to right, with the boolean result show at the extreme right.
Rung wire conductors are identified by adjacent alpha/numeric ID's.
In Europe, the top down method is often used.
In panel wiring where the physical layout is shown, the only useful details are the termination points maybe.

 

The electrical wiring protocols and the ladder diagrams serve a different purpose - The ladder diagram defines the flow of control logic.

I want newcomers to understand what does what in the panel, and what controls what - eg this output of the PLC is connected to this terminal of contactor No. 3 (which might be in a different panel). Looking up wire numbers across multiple pages is laborious.

My electronic PCB and schematic software will highlight a connection to a component when you click on the wire (line) and the connection will flash on another part of the drawing even though the line representing the connection is not drawn in. That helps me to understand an unfamiliar circuit. Hyperlinks in a webpage or .PDF do something similar.

I was wondering if there is something similar in general use for large wiring diagrams.

Thank you for your suggestions.

 

Well I have been servicing Industrial machinery for some decades and primarily use the ladder format schematics for servicing and on occasion , the location of an individual panel located item.
As per the previous referenced NFPA79.
Many systems will offer display on a portable unit or PC for e.g.
On many, most useful, The S/W will high-light the particular rung function when it is active or conducting in order to display whether the logic path is completed or not.

 

I haven't the NFPA79 document. I wonder if it carries recommendations for documentation of control systems. 'Could be useful if it does.

 

If there are a lot of address or data lines , they are sometimes shown as a buss, with angled lines entering. then it is sort of possible to see that the 8 or 16 lines go from a set of outputs to sets of inputs. And the heavy line indicates multiple signals in one line.
Please avoid colors because that does not work for very long.
Non-uniform spacing of parallel lines makes following a bit simpler. And certainly arranging the blocks so the signal flow is in a fairly consistent direction also helps follow it. And always, pin numbers outside the device box, and function or signal names inside the box.

As a last bit of help, a net list with signal names will help both the PCB layout checker and any service person trace things. and it is vital for any wire-wrap construction.

 

There is an older version of NFPA79 out there that gives the idea. https://atapars.com/wp-content/uploads/2021/01/atapars.com-NFPA-79-2007.pdf
Towards the end is the documentation formats, this version shows the European top down method of ladder for some reason??
There is basically 3 display types, the ladder diag, the Cabinet physical wiring, and enclosure component layout.

 

Certainly enclosure layout is very important, both for function and for safety, as well as assuring that it all fits. A well thought out ladder diagram is a very valuable tool, the most important of all.
A cabinet physical wiring drawing is very seldom needed unless there are low level signal circuits involved. And connection and cable details work best on their separate sheet, unless the whole system fits very well on a single sheet. Of course, individual elements must be identified on the sheet that they appear on, although that may be by ID tag rather than model number. The BOM may appear on the enclosure layout sheet if it is not extensive, and will fit easily.

 

Thank you(s) for the information.
It looks as if there is no one best way, and it depends on the end use.
I shall use some combination of block diagrams, netlists and wiring diagrams.

 

Block diagrams and wiring diagrams work best for understanding how a circuit works. Net lists work best for auto-routers and wire wrapping.

 

Hi.
I am drafting a schematic/wiring diagram for a large electrical panel.
At present it has the components - contactors, controllers etc showing numbered wires. None of the wires of "nets" are joined up on the drawing. This makes it difficult to grasp how the components relate to each other.
I would appreciate your advice.

Does the panel include any kind of intelligent controller such as PLC etc?
These use the form of ladder logic that I referenced earlier, these typically use cross reference sub objects that are related to the main unit, e.g. contacts pertaining to a main contactor unit etc.
and are labeled as such .
What or who is the end use of the drawing intended for ?

 

Labels can be very helpful, "Pump#1 " for a motor starter "HSV#1" for a hydraulic solenoid valve, and even for indicator lights, if an HMI (Human/Machine Interface) display is not used. Consider that at some time, somebody will need to start the machine the very first time, and if any portion does not function as required somebody will need to understand why, and correct whatever was not correct. That may be the designer, or it may be somebody who has never seen the system before. I have been both of those persons, and thus I can vouch for the value of labels.

 

The panel has a fanless Intel/Windows computer and two data loggers that we design ourselves. The panel has connections to sensors and battery charge controllers. plus connections to other panels like it doing other tasks.

Th purpose of the documentation is to help newcomers learn them and also provide comprehensive information for maintenance personnel.

The software for the fanless computer and data loggers is documented elsewhere.