The SF100 series modular cubicles, integrates in a little module filled , with sulphur hexafluoride gas (SF6) the necessary switchgear for each one of the operation and protection functions on transformation centers of electrical utilities loop distribution networks, and also on medium voltage industrial and wind turbine parks distribution networks, up to 24KV. The connection between them is performed by an air insulated busbar, accessible through the front door. The switches are rotatory type of three positions: Open, Close and Earthed; and due to its special high security design, there is not possibility to connect the earthing without the previously opening of the switch.