plc prints

[georgia boy]

hi guys

i am kind of new to print desighn standards . my application is i have a micrologix 1000 plc and i have a program that opens air solenoid vales on a conveyor system . when we have problems with these valves they have liquid tight all the back to the control panel so the easiest place to test the coil is the control panel . the L1 lead of any coil is easy to find because the address is marked on the terminal block . but the L2 side of any coil is marked L2 on the terminal block . with there being so many it is hard to find which leads to test. how can i mark these terminal blocks so that you can find each L2 wire and know which valve it goes to . but also still know it is L2 . also should my terminal blocks which contain plc output wires be labeled with the plc address or the wire refrence number from the print. if wire refrence how do you distingish between them . the print i have has 1 for L1 and 2 for L2 and these could be going anywhere i need to know how to use and label terminal blocks correctly

thanks in advance

gb

 

[olias]

Just curious, what is the coil voltage.

 

[kamenges]

Originally posted by georgia boy:

with there being so many it is hard to find which leads to test. how can i mark these terminal blocks so that you can find each L2 wire and know which valve it goes to .

I am assuming (I know, bad idea) that all the L2 wires on your valve are common. That is, all the wires labeled L2 tie to the same voltage reference. If this is the case you should be able to test from the 'hot' wire (L1) to any L2 and get just as valid a result as if you test to the actual L2 wire from the specific valve.

I have seem a few different schemes for terminal numbering. One of them simply labels the terminals in order starting with 1. You then need the print to determine which wire number should go to a specific terminal.

Another option that doesn't count on numbering is to use isolated dual level terminal blocks. Leave the top level independent for your 'hot' wire (L1). Tie all the bottom terminals together for your L2. Then put the L2 from any given valve into the same terminal as the L1 wire for that valve. This method, like any of them, relies on the discipline of the terminator to keep the system valid.

Keith

Keith

 

[Jimmie_Ohio]

For what you wish to do, I don't believe there is a design standard, assuming of course that the existing drawings reflect a design that meets all applicable codes.

What I would do here is to segregate the terminals you wish to test at the terminal strip by color. Several manufacturers sell different colored terminals. I would then label the areas above with an engraved tag indicating that these two terminals are for SOL1, SOL2, etc. Since the neutrals are jumpered anyway, you would have a specific test point assigned this way.

Be sure the final drawing reflects this. If you look at the terminal block manufacturer's accessories, you will generally find some neat marking options. I cannot make spacific suggestions unless I know which make and style you now use.

Hope this helps...

 

[Tom Jenkins]

I insist on wire numbers at both ends of every wire. My rule is that any wires that are going to be at the same voltage at the same time carry the same wire number. In other words, all leads directly connected to L2 as it enters the panel will have the same wire number, and I can connect to any of them to test. If a wire passes through a device, such as a switch contact, the wire number changes. Note that a terminal block, electrically, is not a device and the wire on both sides should carry the same number.

 

[mellis]

This is a pet peeve of mine...

When the electrician is landing the wires in the panel, they may say "all these terminals for neutrals are all the same, I'll land the wire on anyone I feel like". I prefer to keep track of which neutral is going to which valve. Sure they will work as long as all of them get terminated properly. But it doesn't make it easy to troubleshoot if one of them happens to have a bad connection.

What I like to do is use double terminals and land the output wire on the top deck, and the neutral wire that goes with that output right below it on the bottom deck.

I once designed a SLC remote I/O panel that served up to 64 automated ball valves (1 out and 2 in for each). The plant didn't like the double terminals and insisted I change it to all single terminals with one long +24v strip and one long common strip. It works, but if you lose the +24v at the valve for the position switches, good luck finding which of 64 randomly terminated wires in the panel is loose.

 

[mellis]

As far as wire numbers go, I am in agreement with what Tom said. And I find that fairly standard. One additonal item..

I generally use the plc address on the input or output wire. However, I do not try to put these long numbers on the terminals. I like slot-channel for terminal numbers. For example, for a 16pt input card in slot 3, I would use 16 double terminals numbered 3-0 though 3-15. Or, you can put the slot number on a divider between each group and simply number the terminals in each group 0-15.

 

[leitmotif]

This is a pet peeve of mine...

When the electrician is landing the wires in the panel, they may say "all these terminals for neutrals are all the same, I'll land the wire on anyone I feel like". I prefer to keep track of which neutral is going to which valve. Sure they will work as long as all of them get terminated properly. But it doesn't make it easy to troubleshoot if one of them happens to have a bad connection.

AMEN AMEN

What I like to do is use double terminals and land the output wire on the top deck, and the neutral wire that goes with that output right below it on the bottom deck.

YOU ARE impacting the job security and the joy of challenges for maintenance electricians. We dont have anything better to do than chase "lifted neuts" and we are bored without them. We just love untangling 20 or 30 wires all wrapped around each other.

I once designed a SLC remote I/O panel that served up to 64 automated ball valves (1 out and 2 in for each). The plant didn't like the double terminals and insisted I change it to all single terminals with one long +24v strip and one long common strip. It works, but if you lose the +24v at the valve for the position switches, good luck finding which of 64 randomly terminated wires in the panel is loose.

YEAH now that is the challenge I am talking about. I just dig it.
RO WWWW FFFFF

Dan Bentler

 

[georgia boy]

thanks for the various methods guys . i have just seen some terminal strips labeled 1 thru whatever . some have the wire refrence number and some have the plc address . seems to me the 1 thru whatever method may work best . but i wanted the be sure this was the best way to do it

 

[leitmotif]

thanks for the various methods guys . i have just seen some terminal strips labeled 1 thru whatever . some have the wire refrence number and some have the plc address . seems to me the 1 thru whatever method may work best . but i wanted the be sure this was the best way to do it

REPLY In my mind the BEST way is the one that makes sense to those that need to be able to come in at 3 AM and figure out what they did a year ago. I am convinced in electrical work there is NO magic way or the ONE RIGHT way to do things so you do it so it makes sense to those working with it.

Dan Bentler