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EARTHING

The earthing system is an essential part of the power networks at high-, medium- and low-voltage levels. It is the total set of measures used to connect an electrically conductive part to earth. Elensol emphasises on a systematic approach to the design of the earthing systems, concentrating on the building installation aspects. There are internationally accepted guidelines on the design and calculation of earthing ground electrodes. In industrial installations, where both electrical and instrumentation equipment are installed, three types of earthing systems are usually designed and erected to provide safety and protective measures. These are electrical earthing systems, instrument earthing systems and lightning earthing systems. In an industrial unit with sophisticated power and electronic equipment, protective steps should be made to safeguard the instrumentation and the relevant control panels from the sudden high voltages which might hit the earthing system in the event of a fault in the power circuit of the unit. As a standard design practice, to achieve this, a separate earthing system is designed and installed in such industrial units.

 

Under fault condition on a specific point in the overall earthing network, a relatively high amount of rush current flows into the earthing system to find its way to the earth wells. The closer an earth well to the fault point, the greater the portion of the fault current absorbed and drained by that well. The remaining fault current is absorbed by the other nearby earth wells. The fault current value can be calculated and therefore predicted, based on the specification and location of the fault point. There are four factors influential with respect to the fault current value, i.e. the value of voltage applied to the fault point; the pure ohmic resistance of the fault point with respect to the ground, which includes the ohmic resistance of each individual well, as well as the earthing grid conductors, wires and cables; the number of rotating machineries and their rated power at the time of fault; and the distance between the fault point and the rotating machineries. Depending on the overall electrical specifications of an earthing system, established and erected in an installation, measurement of the pure ohmic resistance for any specific point in the earthing network system is practically possible for elensol engineers, through the state-of-the-art software packages used by us.

 

The elensol earthing system design is addressing the requirements of safety of human and animal life by limiting touch and step voltages to safe values; protection of buildings and installations against lightning; correct operation of the electricity supply network and to ensure good power quality; and electromagnetic compatibility, i.e. limitation of electromagnetic disturbances. Our earthing system design ensures that the system can manage all these functions in a single earthing system.