What is earth fault protection for DC system?

Techniques for detecting DC ground faults include insulation resistance monitoring and residual current detectors (RCDs). It is advisable to perform a grounding test using an insulation resistance monitor every morning to measure the resistance to ground.

To prevent the earth fault in both terminals, the DC earth fault relay is used in the DC system. When one of the DC terminals is grounded, it will detect by the DC earth fault locator. The earth fault in the DC terminal needs to attend immediately.

The DC ground point can be any single terminal, existing or added, that is conductive and connected to the ground of the building wiring system and then eventually to earth ground. Connect the DC common point to the DC ground point, making certain there is only one conductive path between these two points.