Wind tunnels, used for aerodynamic and acoustic testing in the automotive and aerospace industries, use one or more electrically driven fans to push or pull air through a test section. Some tunnels have one large fan, while others have multiple smaller fans. Air will either recirculate through a closed loop or be drawn in from the surroundings from one end of the tunnel and exhausted out the opposite end.
Around the wind tunnel, there are several full body access doors to allow for maintenance. It is critical to ensure no one enters the tunnel while in operation. Incorporating a trapped key interlock system ensures the proper sequence of energy isolation is performed. Introducing electromechanical interlocks within the system allows contacts to be tied into a PLC system, signaling when an interlock system has been engaged and the tunnel doors have been accessed. This process prevents unexpected startup until all maintenance is complete and everyone is safely out of the tunnel.