Erdungsstab

摘要

1356353 Earthing rods ALLEGHENY LUDLUM INDUSTRIES Inc 16 March 1972 [16 March 1971] 12343/72 Heading H2C [Also in Division F2] An earthing rod comprises a thin-walled tubular shield 2 of corrosion-resistant material, e.g. stainless steel surrounding a thin-walled tubular conductor 4 of low impedance metal, e.g. aluminium or carbon steel and a core 6 of semirigid, e.g. plastics material substantially filling the tubular conductor. In another embodiment, Fig. 2 (not shown) a further tube (5) of steel may be provided in addition to or instead of the core 6. A driving point 8 may be provided to enable the rod to be driven into the ground and to preclude direct contact between the tubular conductor and the ground. It is stated that the shield and driving point prevent the tube from galvanic corrosion, the tubular conductor enables the rod to handle large current surges and the further tube and/or core permit some flexing of the rod during installation while preventing buckling. The tubes, which need not be circular in cross-section are typically 8 feet long, 5/8 inches O.D. and may have wall thicknesses much less than 0À07 inches i.e. 0À03 inches. The core is preferably under compression in the tube and may be of an epoxy, polyurethane or an elastomeric material i.e. non-reactive with the material of the rest of the rod. The rod may be made by drawing the tubes over the core; if the core has the same diameter as the inside of the tubular conductor then the required compression is achieved. Alternatively, oversize tubes may be used and subsequently drawn down, the tubes may be extruded over the core, or tubes may be filled with a core material that expands on hardening. A coupling device 12 (see Division F2) is also described.