Description
Application
With direct current, the risk of possible stray currents must be prevented by connecting the return conductor directly to the water earth. Stray currents would damage buildings, bridges and other metallic (electrically conductive) systems and system components through corrosion. Hazards also arise from impermissibly high contact voltages. One of the measures to protect people from impermissible touch voltages is the temporary short-circuiting of the various earthing systems in accordance with DIN EN 50122-1 (VDE 0115 Part 3).
Description
The WITT EKS 8 is an independently resettable Earthing short-circuiter in accordance with DIN VDE 0115 Part 300 and Part 320. It can be parameterized and used to monitor voltage differences between the return conductor and water earth. The combination
of anti-parallel thyristors and a power contactor guarantees a short switching time and a high current carrying capacity. This Earthing short-circuiter has a particularly compact design.
Function
If the entered voltage curve is exceeded, the Earthing short-circuiter responds, i.e. after the switch-on criteria have been met, the thyristors are ignited simultaneously and the contactor is switched. The thyristors switch in a few microseconds, the contactor has a closing time of approx. 90 ms. When the thyristors ignite, the voltage drops to a few volts. The thyristors remain energized until the closing of the contactor is detected by the position of the contactor’s auxiliary contacts. The thyristors are then extinguished. The contactor then takes over the load.
