The section insulator (SI) is a device installed in the catenary system for electrical separation of two electrical feeds while allowing for the passage of a vehicle pantograph, such as in a crossover between two adjacent tracks.
The SI is designed to take into account all of the required electrical clearances necessary for the system voltage.
The SI shall consist of an insulator located in the messenger wire above an insulator located in the contact wire immediately below it. The contact wire insulator is designed to allow passage of a vehicle pantograph across it. To ensure continuous current collection during the pantograph passage, the SI unit contains a side runner located on each side of the unit; the side runners overlap. To ensure correct alignment of the unit, adjustable hangers are installed from the messenger wire to the lower section of the unit.
The section insulator shall be suitable for use on a high-speed auto-tension catenary system. The section insulator shall accommodate multiple pantograph passes at speeds from zero to the maximum operating speed.
Other Section Insulators Examples;
Related Standard; EN 50119 – Railway applications. Fixed installations. Electric traction overhead contact lines
Sources; gotransit.com; aflury.ch