General safety switch knowledge

In the event of danger, the escape release must allow unlocking without aids from the danger area/machine side. The device must be manually operated and act positively on the locking means. The actuation must lead to a permanent blocking of the guard locking (see also auxiliary unlocking).

Emergency unlocking is used to unlock guard locking in an emergency. Unlocking can be performed without tools from the access side/outside. During emergency unlocking, the switch engages in the unlocked position and can only be reset to the initial position with a repair-like effort.

Safety Integrity Level is the level that describes the probability that a safety-related system will perform the required safety functions under all specified conditions within a specified period of time. For this purpose, the Safety Integrity Level to be achieved (SILr; the "r" stands for "required") is compared with the "actual" SIL that is achieved.

If a guard locking device fails, it can be unlocked with an auxiliary unlocking device from the access/external side. Unlocking is performed using a tool or a key. The auxiliary release should be secured against misuse (lead seal, varnish).

Discrete level that specifies the ability of safety-related parts of a control system to perform a safety function under foreseeable conditions (definition according to standard DIN EN ISO 13849). In simpler terms, the performance level is a measure of the reliability of a safety function. A distinction is made between the performance level to be achieved (PLr; the "r" stands for "required") and the "actual" PL that is actually achieved. There are five performance levels, which represent different residual risks.