Safety of machinery

Hazardous machines and systems are frequently equipped with safety elements (safety doors) with a locking mechanism to protect the operator. Their function is:

a) to prevent hazardous machine functions if the safety door is not closed and locked,

b) to keep the safety door closed and locked until the risk of injury has passed.

A general example: A machine has one or more maintenance openings (part-body access) or is accessible through one or more doors (full-body access). On the one hand, it has to be secured that the machine isswitched off, before one of these openings or doors can be opened. 

 Trapped-key interlocking system HST: Safety of machinery

...On the other hand, the machine must only be re-set into operation, if all openings and doors are closed, and nobody is present inside the machine.

door interlocking