(In some cases the sections are run with different voltages or frequencies.) The grids could be synchronised on a normal foundation, but functions may well interrupt synchronisation. This is simply not a problem for DC devices. AC programs have a certain basic safety implication in which the railway electrification process would work as a "Backdoor
Trolleybuses utilize a 2nd parallel overhead line for that return, and two trolley poles, one particular calling Every overhead wire. (Pantographs are typically incompatible with parallel overhead lines.) The circuit is done through the use of equally wires. Parallel overhead wires may also be employed within the unusual railways with 3-stage AC ra
[9] Once the overhead line was raised in the Simplon Tunnel to support taller rolling inventory, a rail was applied. A rigid overhead rail may be Utilized in places the place tensioning the wires is impractical, for instance on moveable bridges. In modern uses, it truly is very common for underground sections of trams, metros, and mainline railways