While operating DC traction systems with return conductor via the running rail voltages can occur because of the different earthing resistance. These voltages can be hazardous for passengers and equipment. One of the measures to protect passengers against impermissible touch voltages is the temporary short-circuiting of the various earthing systems according to EN 50122-1
The newest Witt short circuiting device is already conforming with the most up-to-date version of the European norm EN 50122 and was developed for Berlin Metro (S-Bahn).
Additional information about the range of protective devices for DC operated rail systems you can find in our brochure: