I have started to document the electrical system in a custom machine that we own. I'm using TinyCad for the schematic and that's working OK. I also want to create wiring diagrams to represent the routing of wires, which DIN rail they equipment they are connected to is on, etc.

I'm new to ALL of this. I'm trying to figure out why DIN rail mounted terminal blocks don't seem to be represented on the diagrams I see when I google. To be clear, I'm referring to terminal blocks like this:

enter image description here

Two questions:

  1. Is there a standard symbol used to represent a terminal block?
  2. Is there a reason why I don't see terminal connections depicted in wiring diagrams?

In my experience, and what is the format in several CAD packages I have used is something similar to the following, for the schematic view you have the following:

Figure 1

Source : Link

Above the Terminal Blocks are the circles, label TB1:9 through TB1:14 on the right. Which stands for Terminal Block (Strip) 1 - Terminal 9 through Terminal 14.

And usually there is a Terminal Block Overview which would look similar to this:

Figure 2

Source : Link

Which depicts a three level terminal block, and the wires (cables) connected on each side, and where those cable go.

These are certainly not the only ways, but is common to several CAE Systems I have used.

  • \$\begingroup\$ Thanks for the reply Tyler. I get it, I think. Let me confirm some things: 1) In the first image you posted the content to the left of the dropshadowed arrow isn't relevant. 2) A "terminal block" isn't the individual terminal, but rather is 1+ terminals together on a DIN rail. 3) TB1:9 through TB1:14 I presume are single circuit terminals (i.e. single level). If this isn't the case, what is the notation for multi level terminals? \$\endgroup\$ – Steve K Dec 26 '17 at 23:33
  • \$\begingroup\$ I would also like to ask what application those screen shots came from, if you know. I'm always interested in learning about new tools. Especially something that may have terminal block support. \$\endgroup\$ – Steve K Dec 26 '17 at 23:34
  • \$\begingroup\$ 1) Yes, that image came from an Autocad Electrical terminal block tutorial, it is a before and after (adding terminal blocks) picture. 2) Yes, a "terminal block" can have more then one circuit, as seen in the second picture, they are three level (circuit) terminal blocks. 3) In the second image you can see they used "top", "mid" and "bot", I don't think there is a consensus on the "correct" way. I have used "A", "B" and "C" just to keep it shorter. This constraint mostly comes from the physical installation of labeling the terminal blocks. You could number them all sequentially. (continue) \$\endgroup\$ – Tyler Dec 27 '17 at 13:24
  • \$\begingroup\$ But then you would need to get pre-printed terminal block number to increment by three. As far as CAE packages go there are several I have had experience with, as mentioned earlier, Autocad Electrical, ELCad, and Promis-e. This is not a recommendation (as recommendations are off limits) just some names to get you started. \$\endgroup\$ – Tyler Dec 27 '17 at 13:29

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