Challenges of new technologies non-based in SF6 for operating and protecting MV power transformers of distribution networks

The introduction of new SF6-free technologies in MV electrical networks requires to adequately solving the challenges, which were well solved with SF6 technologies along last decades and still today. One of those challenges is to provide appropriate protection and operation to MV power transformers. This paper shows which are the necessary considerations to take when selecting the technologies, and how a new simple design of three-position switch-disconnector and earthing switch operating inIndustrial Natural Airis able to provide equivalent performances as SF6 based ones provide for most of MV power transformers used in for distribution networks at voltages of up to 24 kV.