Witt Solutions GmbH
The WITT EscS 7 is an auto-resetting earth short-circuiting device that accords to EN 50122 regulations for the protection of public and infrastructure. It is the only product available on the market that fulfills the newest requirements of the DIN EN 50122-1 and DIN EN 50122-3 regulations. Not only does it monitor DC and AC but also the interaction between the two voltages relative to the return conductor and the ground. A combination of anti-parallel thyristors and power contactors ensures a short switching period and high current carrying capacity. This device is built in an especially compact design. The WITT EscS 7 has been evaluated and certified by the Federal Railway Authority (Eisenbahn – Bundesamt) under the ID number: 3343340/0/016.
Function
If the set voltage curve is exceeded, the earthing short-circuiting device reacts. That means that if the criteria are fulfilled, the thyristors are triggered and simultaneously the contactor is switched. The thyristors switch in a few milliseconds, the contactor closes in approx. 60 ms. When the thyristors have been triggered, the voltage collapses to a few volts. The thyristors remain triggered until the contactor has been closed, which is confirmed by auxiliary contacts on the contactor. Afterwards, the thyristors are turned off and the contactor takes over the load.
