motor control

[wgreen]

I am in a basic PLC class, just learning, can anyone give me a ladder diagram for a three phase motor, running forward, (non-reversing), that can also be jogged. One stop, one start, one motor. Thanks

[olias]

This is an excellent way to learn to program. This is as simple as you get. Good luck and stop asking others to think for you.

[mark sutherland]

come on you just want your course work done for you ill give you a clue you need 3 inputs 1 output and 2 retaining coils now use your brain and try

[olias]

Actually, He only has two inputs, start and stop, so he'll have to hold the stop button and jog with the start. Now, he only needs one output.

[JDW]

start Phase
A
---| |--------------------------()-
Start phase
B
---| |--------------------------()-

start phase
C
---| |--------------------------()-

[mark sutherland]

Ok though you had a jog switch as well.are you running the 3 phase motor from the PLC or through a contactor.

[Tom Jenkins]

This is a standard motor control ciruit. If this is an industrial application you should have some manufacturer's catalogs laying around that you can look at for hints. If this is a student exercise, yopu should make an attempt, however feeble, and post it here. We will then give more hints and critique the logic.

[rsdoran]

I can offer 2 sites that may help you in this endeavor

http://claymore.engineer.gvsu.edu/~jackh/books/plcs/
download the PLC harware PDF

http://www.reliance.com
Has abundance of info pertaining to motors and controls

As stated your request is for a simple circuit that is easily found if you take the time to look and read. If we misunderstood your question then rephrase and ask again please.

[DickDV]

In my experience, jog can mean at least two different things.

First, it can mean that there is a separate jog button that, when pushed causes the motor to run, and when released, causes the motor to stop. Operation is completely independent of the start and stop buttons.

Second, it can mean that there is a two position selector switch which, in run position, causes the start button to latch up leaving the motor running until the stop button is pushed. In jog position on the switch, the start button causes the motor to run when pushed and does not latch up, allowing the motor to stop when released.

The control scheme for these is significantly different.

[wgreen]

Sorry if I didn't ask my question correctly, I diagramed a logic ladder with a stop, start, overload, memory, and ote, when I added the jog button the program would not run, after working on it for three days I ask for help because I thought there was something I was doing wrong. Tonite in class I discovered that it was a trick question and I have not been given all of the necessary info. I have since figured it out. Sorry if I was confusing.

[Mr. Allen Bradley]

start stop overload contactor coil (C1)
-----||-------------------|/|---------|/|----------()----
|
C1 JOG |
-----||--------|/|---|
|
|
JOG |
-----||--------------|

try it!

[Mr. Allen Bradley]

excuse, they have some problem with my last reply

[Mike Williams]

Mr. Allen Bradley, Please lower your prices!

[Steve Bailey]

Mike, I expect that your solution is for a separate 'Jog' pushbutton wired as a normally open device, and the intent is to have the motor run while the Jog pushbutton is pressed and stop when the Jog pushbutton is released.

Unfortunately, The logic that you presented will not work that way. The starter will seal itself in with the Jog pushbutton just as it will when the 'Start' pushbutton is pressed.

[Mike Williams]

I put up what MR. AB attempted to show just that. YOU CAUGHT IT TO QUICK! You guys are awsome.