Summation current sensors play a central role in earth fault detection in medium-voltage grids – especially in so-called RESPE grids (resonant earthing with voltage limitation).

The summation current sensor is generally used for earth fault detection in medium-voltage networks, the RESPE networks, with the Sigma D+. It enables the precise detection of earth fault currents, even at very low fault currents, and thus supports the rapid localization and signalling of earth faults in the network.

By using a suitable summation current sensor in conjunction with a directional fault indicator such as the Sigma D+, faults can be detected selectively – regardless of the neutral point treatment. The sensor is typically routed around all three phase conductors and measures the residual currents with high accuracy.