What Is a Safety Plug?
A Safety Plug is a so-called interlock plug.
An interlock refers to something that restricts the movement of a machine or other equipment by making it a condition of operation.
Installing Safety Plugs in production and industrial equipment can stop their operation when a person unintentionally pulls out the Safety Plug. They are often installed in operating parts that may cause harm to people and play a very important role in ensuring the safety of workers.
Uses of Safety Plugs
Safety plugs are installed on the doors of safety enclosures situated along production lines, as well as on the doors of machine tools and industrial machinery. Some products are also installed in the operation panels of equipment and devices.
In the case of production lines, Safety Plugs are often employed as keys for safety doors. The Safety Plug cannot be easily pulled out while the production line is in operation. If a worker pulls out the Safety Plug while the production line is in operation, the production line will immediately stop operating, thus avoiding human casualties.
Principle of Safety Plug
The Safety Plug acts as an interlock in the electrical connection.
Production lines are often line-controlled by PLCs. In this case, there are two types of interlocking: interlocking by logic circuits in the PLC program and interlocking by hardware connections such as IO communication.
The Safety Plug is connected to the PLC hardware (electrically), and it plays the role of an interlock using IO communication. When the Safety Plug is removed, the electrical connection is interlocked, and the PLC doesn’t need to perform any logic calculations. Instead, it simply monitors the status of the electrical communication to determine the state of the Safety Plug. Thus, if the Safety Plug is pulled out, a process can be immediately implemented to shut down the production line.
To create an electrical connection, Safety Plugs integrated into safety doors often consist of two components, typically a key and a keyhole. These components are configured so that electrical communication is activated when the key is inserted into the keyhole and deactivated when the key is removed from the keyhole.