Machinery Protection Devices - British Automation & Robot ...

5.3 Emergency stop devicesEvery machine must be fitted with a control to bring it to a completestop safely. On a complex machine, each workstation must be fittedwith a stop so that all or some of the moving parts can be renderedsafe. Where machinery has complex movements or high inertias, thestop function must not cause damage to the machine or create adangerous situation. This means it is vital to consider the way inwhich the machine is brought to a safe condition. The energy supplyto the machine’s actuators must be removed once the stop has beenachieved.Section 9 of EN 60204-1 categorises stop functions as follows:Category 0: Stopping by immediate removal of power to themachine actuators, all brakes or mechanical devicesbeing activated (i.e. an uncontrolled stop).Category 1: Stopping by means of the machine actuators (i.e. acontrolled stop). Power is finally removed once the stophas been achieved.31127Machinery ProtectionDevicesCategory 2: A controlled stop with the power left available to themachine actuators.In reality, all machinery should be fitted with a category 0 stopfunction, but where safety or functional requirements demand it,category 1 or 2 should be provided. Category 0 and 1 stops havepriority over all machine functions.