A new deal for safety and quality on MV networks

Various neutral grounding techniques are applied in medium voltage distribution networks throughout the world. This is due to the fact that implementation of a particular grounding solution is the result of compromise between several objectives which are sometimes contradictory. The right compromise depends on the physical characteristics of the networks, type and density of load and the importance awarded to safety and power supply quality. Use of digital protection and automatic control systems may also have an impact on selection criteria. The authors of this paper summarize the major possible alternatives and the reasons which may lead a utility to modify its original choices. Developments by EDF are analyzed and the resulting potential benefits in terms of safety and power supply quality are indicated. The result of this analysis is the decision to change the neutral earthing of rural MV networks.