·Safety interlock device is an effective measure to prevent misoperation. Commonly used safety interlock devices include electrical operation safety interlock device, hydraulic operation safety interlock device and combined operation safety interlock device.

·According to the power source that causes the action of safety interlock device, it can be divided into three types: direct action safety interlock device, indirect action safety interlock device and combined safety interlock device.

·The concept of "safety switch", which is widely used in safety switches, position switches and interlocking devices, does not appear in the standard, because there are many sensor designs and technologies suitable for interlocking devices, and it is impossible to define general requirements.