Are there emergency stop buttons, with two circuits and key reset
For a safety application in a civilian nuclear application, we need an emergency stop button which will interrupt two independent circuits when pressed.
Two independent safety systems make current flow - a few mA - in respectively these two independent circuits.
Once pushed, both circuits remain open and current flow is interrupted. Resetting the button shall be done using a key.
No semiconductor is allowed inside the button, since the radiation fields prevent any usage of semiconductors. Passive components like resistances or capacitors are OK. Sensing logic is away from radiation fields.
Thank you for your kind answer.
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Simplest method would be to use a mushroom head EMG push button, with a key lock mechanism.Once the EMG button is depressed, the button can be rotated and pulled back only by way of turning the inserted key in the direction of release.You can use addon NC contacts to increase the number of push to break circuits.
The contacts in this case would be mechanical.I am unsure whether this setup would meet any particular intrinsic safety requirements in a nuclear application setup.