11:2 Deep earthing system Benefits Elpress systems for deep earthing have many advantages: • The ground line has no joints – no risk of contact failure. • Tip and leading rod are manufactured for a large area range; 16 - 95 mm². • Can be used for different types of line e.g. soft or hard copper, galvanized or stainless steel. • When copper line is used, the extension rods act as sacrificial anodes and provide good protection against corrosion. • Full control over the line and tip is maintained and it is possible to continuously measure the earthing resistance. • Thanks to the few components of the system, driving is both uncomplicated and reliable. • The system has a low overall weight compared to other systems. • The overall cost of a complete earth connection will be lower than that made in a conventional manner. • Rod length 800 mm for best ergonomics. Radio base station is an application for Elpress deep earthing systems. Theory Elpress’ approach is an earthing system without joints. The electrode consists of a copper line that is driven down by a system consisting of 0.8 m long steel rods. A hardened steel tip paves the way for the ground line that is inserted into the steel tip and clamped by the leading rod. For every 0.8 m length of driven line and rod, an extension rod is pushed into the preceding rod. Because the earthing resistance can be continually measured at the other end of the line, one can stop driving when a suitable value is reached and the last extension rod is then withdrawn. Driving takes place with the aid of a power hammer with an adapted driving sleeve or a sledge hammer and impact sleeve FS62C. Impact sleeve FS62C Service life Elpress deep-earthing system consists of steel rods and a copper line. The steel rods act as sacrificial anodes with relatively high corrosion current against the copper electrode (cathode). This combination of metal both stabilises and equalises its surroundings. If a lead sheathed cable is located in the soil a few metres from the earth connection, the corrosion current from the lead anode to the Fe+Cu earth connection is 40% less than the value of an earth connection without FE rods. In other words, the lead sheath has a theoretical service life of almost double. Experiments have shown that after a few months, the corrosion current drops to virtually zero. The explanation is that a special layer – the polarization layer – is formed next to the electrode. The current is thereby reduced and thus also the corrosion. The amount of the reduction depends on the properties of the soil. An AC load should theoretically counteract the corrosion. This means that the practical service life is often longer than the theoretical.
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