An interlocking device is usually mounted on a movable guard, e.g. on a door. Usually a stop command is given when the guard is opened and the hazardous movements are prevented during this time. An interlocking device does not need to have a locking function.

Locking devices such as Magne, Mkey and Knox are usually used when the door may only be opened at a specific time, e.g. at the end of the welding operation or when the dangerous movement has stopped.

Locking and interlocking are two different functions. While interlocking is a safety function, locking doesn’t have to be a safety function e.g. if the purpose is to protect the process and not the persons.

Eden is an interlocking device without locking function.

All locks of the ABB Jokab Safety range can be used as process locks but only Knox and the spring lock models of MKey can be used as safety locks. Why?

A process lock protects the process. An example of application would be a lock on a door giving access to a welding machine. The door should not be unlocked before the end of the welding cycle. Should the door be unlocked before the end of the cycle (as a consequence of a fault in the installation like a loss of power or a short-circuit) the process would stop. It might take a long time to restart the process, but no person would have come close to the danger or get injured. 

A safety lock protects people. An example of application would be a lock on a door giving access to a circular saw or another dangerous machine with a long stop time. The door should never be unlocked before the dangerous movement has stopped, not even as a consequence of a fault in the installation like a loss of power or a short-circuit. Should the door be unlocked before the machine has stopped, a person could get close to the dangerous movement and get injured.

Since a loss of power should not unlock a safety lock, only locks that require power for unlocking (e.g. +24 VDC) can be used as safety locks.