Earthing switches complete the range of disconnectors and can be:

• either “stand-alone” (usually provided with their own post insulators);
• or integrated Into any disconnector (with one, two or, in special cases, up to three earthing blades per pole).

Two different types are available (depending on the rated voltage and the rated short-time withstand current): 

• “single-motion” type, where the arm of each pole moves only perpendicularly to its rotation axis up to direct engagement of the moving contact into the fixed one;
• “double-motion” type, where the arm, upon completing its movement perpendicularly to its rotation axis, moves along its longitudinal axis leading to complete engagement and locking of the moving contact into the fixed one.

Under special circumstances, when the distance between the fixed contact and ground is very big, the earthing switches can be of semi-pantograph type (see also HVDC equipment).

Special earthing switches are available for the connection to ground of neutral points: in this case, the earthing switches are equipped with suitable insulators both under the supporting frame and along the vertical driving shaft.

Rated voltage: 17.5 – 800 kV

Rated short-time withstand current: up to 80 kA (1 s)