Control wiring

I'm wiring a project in which I'll have a series of solenoids and limit switches in order to determine where a slide is in place. I have all the I/O's, I just need to know how to hook it all up. I've got the 480v wired to the motors which was no problem, I'm just having trouble figuring out which limits and solenoids would be Inputs and outputs and how to run the wire. The 480v is run through one conduit while I have the control going through another.

The limits would be inputs.
The solenoids would be outputs.

You say you have the 480 wired to the motors, I'm guessing you have wired the 480 to contactors?

Do you have drawings?

I have a concern about your level of expertise and whether you should be attempting this project.

I have a concern about your level of expertise and whether you should be attempting this project.

Click to expand...

I second that motion.

DJM said:

The limits would be inputs.
The solenoids would be outputs.

You say you have the 480 wired to the motors, I'm guessing you have wired the 480 to contactors?

Do you have drawings?

I have a concern about your level of expertise and whether you should be attempting this project.

Click to expand...

I have concerns about my own expertise at times. Safety is an issue because electricity is involved, so it would be appropriate if the level of training in this area was known.

If the electrical aspect is of no concer i.e. you are maintenance or equivalent that may work with it but not familiar with plcs then I will address the plc part.

A plc is just a "brain" of a sort just like humans, it needs to have input before it can decide on an appropriate output. In other words an action has to be perceived (input) to determine if an action (output) is needed or decide what action (output) is appropriate. Example1: Your stomach growls, this is an input that tells you "time to eat something". Example2: Wife says "Honey do..., may have to leave TV and big game...LOL, may reset timer to delay that action.

Some forms of digital inputs for a plc:

1. Pushbuttons
2. Switches: on/off, auto/off/hand ....
3. Limit switches
4. Sensors: proximity, inductive, photoelectric, capacitive..
5. Auxillary contacts from contactors, drives,......

Digital inputs use devices that send a signal to the plc, how the plc reacts depends on how it is programmed to react with that signal.

Some forms of digital output signals:

1. Relays, for isolation or for use with a different voltage...
2. Contactors or starters, motor, lights, or any load that requires 3 phase and/or high currents.
3. Solenoids or valves: this could be any fluidpower type actuator.
4. Motor drives or other type controllers.

I did not see a brand of PLC stated so picked one with an online manual that offers examples of wiring:
http://web3.automationdirect.com/static/manuals/d006userm/d06uservol1.pdf
Look at Chapter 2.

To address your specific question, as mentioned, the limits will be inputs and solenoids (valves) will be outputs.

Thanks Ron for your very tactful and thorough reply. I am sometimes sorely lacking in that regard, but my concern was this persons safety and it was never my intent to condescend. This almost looks like a class project, possibly tech school. I can't imagine someone being thrown to the wolves in the field to this degree.. well; except for me, most of the time!

Other things to consider:

Are the inputs and outputs 24 VDC or 120 VAC? Are the devices NPN or PNP? You said series, how many? What are the power requirements? Will you protect the output of the modules with fuses? If it is 24 VDC, will you ground one side or float the voltage? Moving slide - what are the safety aspects? Are there guards? Are e-stops needed and hard wired? Is the system properly grounded? Is there a starter for the motor and are the overloads properly sized? Is the starter rated for the available short circuit in case of a fault? Is there primary protection? Has this been coordinated with the upstream devices? In your panel with the plc and starters, have you done an arc flash calculation? Is there a risk assesment for the system? If this is your project, then these items (and many more) must be addressed.

The Inputs (Digital)are
Push Buttns,
Switches,
Sensors,
Commands from other PLCs/DCS or MMI,
Contacts of relays, timers etc
IN order avoid signal interferance better to use screened cable.

The outputs are
Lamps,
Announciator,
Solenoids,
Relay/Contactor Coils for Stating motors etc.,
Feedbacks to VDU and Data Loggers/DCS/PLCs.

For 480v output applications better to connect the output through interposing relays of 24v DC (or may be any other voltage as per standard of respective PLC being considered) It is not advisable to directly take 480v to PLC.

R.Thiyagarajan.