Earthing

EARTHING: o Purpose: To ensure safety of life and apparatus against earth faults. o System Earthing: Earthing associated with current carrying power conductors, usually neutral conductor, is normally essential for the system. o Safety Equipment Earthing: Earthing of non-current carrying metal works of equipment bodies is essential for the safety of life and property. o Basic requirements of Earthing : 1 Should capable of carrying the earth fault current and to avoid dangerous contact potentials being developed on metal works. 2. Should limit earth resistance sufficiently low to permit adequate fault current for the operation of protective devices in time and to reduce neutral shifting. 3. Should be mechanically strong, withstand corrosion and retain electrical continuity during the life of insulation. o o o o o o

Earthing shall meet the requirement of IS: 3043. Importance in the process area: Earthing Installation grade. Earthing Installation Overhead Earthing Installation for Buildings/substations/analyzer house/pump station. The resistance of electrical system shall be: a. Electrical systems and equipments: A value that ensures the operation of the protective device in the electrical circuit and not in excess of 1 Ω. b. Lightning protection: Not in excess of 5 Ω. c. , static electricity: 1 MΩ.

o Types of Earthing o Measurement of Earth Resistance of Electrode. o Formula For Earth Resistvity ` o Acceptable value for Earth resistance. o I.S. for Earthing.