Low resistance terminal embedded in rock - has oil and carbon mixture between concentric tubes separated by apertured diaphragm

摘要

The earthing terminal comprises two concentric tubes (1,2), with the inner tube (2) passing through the top end plate (3) of the outer tube (1). The inner tube is fitted to the bottom end plate (7) of the latter. The inner tube (2) is of metal, while the outer tube (1) is made of metal, plastics or an insulating material. The space between the tubes (1,2) is filled over the bottom two thirds of their height with a mixture (6) of oil and carbon powder, with a plate (5) separating it from the remaining third which is filled with oil (4). This separation plate (5) has a central aperture for locating the inner tube (2) and smaller surrounding apertures (9) allowing infiltration of the oil (4) into the mixture (6). The earthing terminal exhibits a low resistance.