Safety functions: Stop functions and their standard reference

Stop functions are found on almost all machines. EN 60204-1 defines 3 categories of stop function for the various functional requirements:

• Stop category 0
• Stop category 1
• Stop category 2

A category 0 stop leads to an immediate removal of power to the machine actuators. Activation of the mains isolating device automatically triggers a category 0 stop, as power is no longer available to generate the movement.

With a category 1 stop, power to the actuators is maintained to enable a controlled stop.

Stop category 2 is used if power is required even in a stop condition, as power is maintained after the controlled stop.

These stop categories should not be confused with the categories in accordance with EN ISO 13849-1 or EN 954-1, which categorize structures with a specific behavior in the event of an error. For speed-controlled drive systems, EN 61800-5-2 assigns stop functions to the stop categories listed in EN 60204-1.