Estop Design Advice

I have 4 pieces of OEM machinery that need to work together and they are in very close proximity and some mechanically connected to each other.

I have all the signals between them figure out but they each have their own estop system and I wanted opinions on if I should connected all the estop systems together and what is the best method.

I don’t know if they have to be connected or not but I remember once hear that any estop within sight of the equipment should stop it. Is this true and how firm is it?

What is a more clear definition of within sight? As there are a lot of estops within sight in the cell areas on either side that I would not want to stop equipment in this cell.

If I do connect them together I was thinking of using the new guard master safety relay based on the micrologix 800 from Rockwell and taking a relay contact from each OEM’s control cabinet as an input to the guard master and an output from the guard master driving a relay in each OEM’s estop chain.

I was thinking of programming it so that if an estop is hit on machine A it will trigger the estop relay in machine B, C, D and if an estop is hit on machine C it will trigger the output to A, B, D etc.

They guard master would be mounted in a control bucket in the MCC for that cell and the reset would be there and I can have the guard master outputs trigger the individual resets from there.

I would also have 4 pilot light on the mcc control bucket to indicate which OEM system triggered the estop

Any feedback on this proposed design method would be helpful

...they are in very close proximity and some mechanically connected to each other.

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I think that the "mechanically connected" fact would mean that Machine 1 could pass energy or cause a hazard on some other machine, so that the E-stops would also need to be interlocked together.

There could be a case where Machine 1 can pass energy to Machine 2, but not vice versa (Machine 2 cannot affect Machine 1). In that case, if #1 E-stop is pressed, also activate #2, but if #2 is pressed, do not activate #1.

What about any estop within sight should stop the machine? Is that correct?

What about any estop within sight should stop the machine? Is that correct?

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I don't think so. If the machines within sight work together "in a coordinated manner", then all the E-stop NC contacts should be connected in series. But if a machine cannot be easily confused as being part of or working with other machines (a complete packaged, stand-alone machine), then I don't see any standards that require it to be shut down when other machines in the area are shut down by an E-stop.

It comes down to making the risk assessment and deciding which E-Stop connections would be the safest and least confusing to someone needing to stop ANY machine in a hurry. Having clear names and labels on each control panel and E-Stop button will help a lot for operator safety during an emergency stop.

Using the programmable relay is a good idea IME. Once the cell goes live there'll likely be complaints from operations about the e-stops killing everything. The relay will make your life way easier IF operations can get EHS to sign off on changing it