Technical requirements and field experiences with MV DC switching equipment

DC systems have been used for certain applications in the past. Compared to AC, DC systems have a better transfer capacity, improved flexibility, and controllability, and are able to provide better power supply reliability. DC power brings a strong set of attributes for the grids and its challenges, including lower distribution losses and higher power carrying capacity.

DC has already been used for a long time in HV. HVDC systems are used to bridge long distances exceeding the physical limit of AC transmission or link systems of conflicting parameters.

Most use of DC is on LV level as electronics applications operate at this voltage level. It applies to both loads and generation. Typical examples for loads are computer and control, converter driven motors and machinery, audio, and video…