Resetting the button should only allow restarting of the machinery and not physically start the equipment directly. Emergency and standby power systems are designed to provide an alternate source of power if the normal source of power, typically the electric utility service, should fail. These are concerned with the safety of. The emergency stop function is a category 0 or 1 stop function in accordance with EN 60204. The preferred sources of power to the EP system are the Normal Station Supply Transformer (NSST) and the Reserve Station Supply. In this guide, you'll learn everything from how to wire an emergency stop switch, understand the working principle of NC contacts, and troubleshoot common issues, with step-by-step instructions and expert tips. Boats, vehicles and other stand-alone applications.