Recent Advances in Electrical Earthing Systems

This paper describes the earthing system that is used in Malaysia, based on British Standards BS7671, focusing mainly on TT, TN-S and TN-C-S systems. The main purpose of earthing is to ensure personnel safety and equipment performance. System earthing is the intentional connection of a phase or neutral conductor to earth for the purpose of controlling the voltage to earth or ground within predictable limits. This paper concentrates on case studies involving nuisance tripping of Residual Current Device (RCD) and equipment damage due to high neutral to ground voltage. By implementing a proper earthing arrangement system based on TT, TN-S and TN-C-S systems and applying a separately derived system, these problems can be mitigated. The description of power quality elements is highlighted herein. The events of neutral to ground voltage disturbance are analyzed using a CBEMA curve. The events of neutral to ground voltage that occur outside the CBEMA curve could easily contribute to the power quality problems mentioned above. With adequate wiring and proper grounding installation, and by adding a separately derived source near the load, the high neutral to ground voltage events can be eliminated