The mechanical interlock is assembled between two contactors to prevent them from simultaneously closing and is often used as an added safety feature to electrically interlocked contactors.
Even with a mechanical force against the magnetic system, the contacts of both contactors cannot close simultaneously.
An electrical interlock consists of two interlinked auxiliary NC contacts. While one contractor (eg 1KM1) is energizing, its interlocking contact (1KM1/21- 22) opens, preventing current flow. During this time current flows through the coil of the second contactor (1KM2).
