PLC Schedule

[will apprentice]

help please

A pressure vessel supplies compressed air to an industrial process.The process operates as follows
1.The process is turned on by pushbutton (S1) and off by pushbutton (S2)
2.A contactor KA1 controls the compressor that feeds the pressure vessel.
3.A pressure switch (Pr1) controls the pressure of the pressure vessel.
4.An indicating light L1 lighting indicates the process is on

Need a Plc input/output ladder diagram for steps 1,2,3,4,

 

[Mickey]

Need a Plc input/output schedule for steps 1,2,3,4,

Seems to me you have already completed it.

 

[will apprentice]

sorry ladder diagram

 

[Mickey]

will, you are going to have to show your work. Then forum members will be happy to help from that point. What brand of PLC are you using?

And welcome to the forum.

 

[will apprentice]

im studing for an exam i failed and i cant find any one 2 give me grinds so i said id give this a try. its a question off an exam paper. sorry if im confusing you

 

[Mickey]

I'm not confused, no one is going to do your homework for you. You need to show some effort and believe me you will get lots of help here. That's what this forum is about.

See my signature, I truly believe it and I think most here do.

 

[Longhorn]

If you look through what you have learned in this subject you have probably covered normally open and closed contacts, coils and how to create your own latches ( seal Ins), exams are usually based on the criteria of the subject e.g. Plc programming, so you should have all the info in your notes required to answer the question.

Draw a sketch of how you think your logic should look.

LH

 

[will apprentice]

-[ ]--------------[/]---------------------[ ]
x0(s1)__________x1(S2)______________mo(KA1)

[ ]----------------[ ]-------------------------[ ]
mo_____________ s3(pr1) ________________ y1(L1)


Any good

 

[kamenges]

First, a little tip on screen formatting. As you have seen the spaces will get pulled out of your post unless you put ladder format tags around the stuff you want put space formatting around. Type it in the way you want it to look, select the area and click on the normally open icon in the toolbar at the top of the editting window. The result will then look like:

 

-[ ]--------------[/]---------------------[ ]

x0(s1)           x1(S2)                 mo(KA1)



[ ]----------------[ ]-------------------------[ ]

mo               s3(pr1)                     y1(L1)

Now for the logic:
How is mo staying on after s1 is released?
If KA1 is the compressor contactor you don't want it on any time the process is enabled. you want it on only when more pressure is required.

Keith

 

[Mickey]

Typically in motor starter logic the pushbuttons are momentary switches. They are only true when they are held in (pushed). So to keep the compressor running after you push the start button you will need a latch around the start button. Usually done with the "mo" contact in your case.

 

[will apprentice]

-[ ]--------------[ / ]-----------[ ]
[mo] . [x1] [mo
[km1]----.

cant get the hang of this

 

[Mickey]

-[ ]--------------[ / ]-----------[ ]
[mo] . [x1] [mo
[km1]----.

cant get the hang of this

If you are working with your PLC's software you might do better by taking a screen shot of your logic then posting that here.

 

[Ned_Flanders]

Are you familiar with basic motor starter circuits? The ladder logic is pretty much identical for a motor stop/start circuit.If you are not, look at this one http://www.europacomponents.com/images/DOL%20Wiring%20Instructions-e774af4de0d443cb400ce28d6181174a.pdf Dont worry about the three phase side of things, just look at the coil, start and stop buttons.(and holding contacts)

 

[Mickey]

Are you familiar with basic motor starter circuits? The ladder logic is pretty much identical for a motor stop/start circuit.If you are not, look at this one http://www.europacomponents.com/images/DOL Wiring Instructions-e774af4de0d443cb400ce28d6181174a.pdf Dont worry about the three phase side of things, just look at the coil, start and stop buttons.(and holding contacts)

Here is an animated version.

http://www.patchn.com/index.php?opt...circuit&catid=18:motors-and-drives&Itemid=116