best spot for E-stop button in a circuit?

[Jeev]

We just got a new machine in and it has 2 PLC's in it. One is a safety PLC that gets all the estops and guards in to it and it shuts off power to the second PLC outputs and gives a input to stop the logic. This way the safety PLC don't have all the control logic scan time in it so it can act faster. Also the HMI can read the guard and estop states from the safety PLC.

If you have motors or pneumatics, and the system does not include contactors, safe stops or dump valves; then I would consider this not to have a safety system at all. It has a control system governed by safety hardware. Our designs haven't used removal of output supply as "safey" for almost 20 years now.

Even a Category 1 stop (Timed, Zero Speed, or Positioned) is dictated by specialist hardware.

 

[Bering C Sparky]

Do you guys have some E-stop button models for recommendation?

Not quite sure what you mean by this, but here is one of the drawings I promised you earlier if this is what your talking about.

This is a SIMPLE circuit that has E-stop, stop, start, and a contactor coil with a seal-in circuit. This would represent a typical starter panel for a single motor.

This is NOT a application of a safety relay. For that type of application look back at willxfmr's post and see the attachment he gave you.

This simple drawing is just so you can get an idea of how this works and where the E-stop would be placed in a simple circuit.

Just to explain a bit so you understand what is happening:
The Red Lines in this case Represent the Voltage carrying conductor.
When you push the Start Button it completes the circuit and energizes the contactor coil.
Since the Start Button is not maintained when you let go of it, it will open back up, which is why you must have the seal-in to keep the circuit in tact so the contactor coil will stay energized.
This is done through the K1 contact, this contact is an auxiliary contact that is on the contactor. When you push the start button and the contactor coil first pull in, so does this auxiliary contact.
So you see how this auxiliary contact routes voltage around the start button and keeps the coil energized.
Now if you push either the E-Stop or the Stop button since they are N/C they will open and break the voltage going to the coil.
The contactor and auxiliary contacts will open and the motor will stop running.

Now look back up at the E-Stop button, you see the second contact on it, this one is N/O (At least in this drawing) when you push the E-stop this N/O contact closes and sends voltage to your PLC input for annunciation that your E-stop has been pushed.

Hope this helps you out a bit.

If you happened to mean actual E-stop button model #'s by what you said in the quote above, then just google 22mm or 30mm E-stops.
I use mostly Schneider brand, but there are many different brands available.

BCS


BCS