The TVM traction drive voltage monitoring is usually used as a voltage monitor for catenary voltage in DC traction systems. This is necessary, for example, when measurements have to be carried out before connecting the different parts of the S-Bahn or U-Bahn.
An electrical connection of the sections may only be made if all voltage values are within a certain window.
In addition, the TVM can indicate high voltages in safety areas, e.g. at the conductor rail of a subway.