Difference between Process Guard Locking and Safety Guard Locking

 

DIN EN ISO 14119:2014 defines the function of a protective device with guard locking. Its purpose is to ensure... 

•    the machine cannot operate when the safety device is not closed and locked   
•    the safety device remains locked until there is no longer any risk of injury            

 

 

 

Due to these requirements, it is essential to differentiate between a  process guard locking and a safety guard locking, as their operational mechanisms are significantly different. A process holding works based on the working current principle and loses power when opened. On the other hand, a safety holding works based on the resting current principle, meaning it stays closed without power, as the actuator is held in place by a spring. A process holding uses an electromagnet to keep the door or access point in place using magnetic force. If the electromagnet loses power, the process holding can open immediately. For example, in the case of a power failure, the door may open right away while movements inside the system are still slowing down. This is why the after-run time and safety distance to the danger zone (see pages 6/7) must always be considered when using process holdings.
In simpler terms, safety holdings are used in systems with long after-run times, while process holdings are used in systems with short after-run times. The C-standard for packaging machines, DIN EN 415-5:2010-04, section 5.2.2.1.7, defines the stop time in more detail. If the system stops within one second after the protective device is opened, a process holding is usually the right choice.

 

 

 

 

 

 

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