WG C4.408 Lightning Protection of Low-Voltage Networks



In recent years, the growing use of sensitive electronic equipment and the increasing demand of utility customers for stability of the power supply have highlighted the importance of improving the reliability and power quality levels of electric systems. As lightning is a major source of faults on overhead lines and damages to or malfunction of sensitive electronic equipment, it is essential to evaluate the lightning electromagnetic environment in order to mitigate its effects and improve the power system quality. Due to the lower withstand capabilities of low-voltage networks (voltages less than 1 kV) in comparison with those of medium voltage lines (voltages in the range of 1 kV to 69 kV), they are more susceptible to lightning electromagnetic interferences.

Joint CIRED/CIGRE Working Group 05 "Protection of MV and LV networks against lightning" was established under SC33 in1993 with the task to prepare an application guide for distribution utilities focusing on practical methods of lightning protection of MV and LV networks, taking also into account economical aspects and quality of supply. After an interruption in 1997, the working group resumed its activity in 2002 under SC C4 with the name JWG C4.402 “Protection of MV and LV Networks Against Lightning” and the following documents have been produced:

  • “Protection of MV andLVnetworks against lightning – Part 1: Common topics”, which is a brochure that presents basic information and principles related to lightning protection of MV andLVnetworks;
  • “Protection of MV and LV networks against lightning - Part 2: Lightning protection of medium voltage networks”,which presents an application of the basic information provided in Part 1 to the lightning protection of MV networks containing overhead lines with system voltage in the range of 1 kV to 36 kV. It is applicable for higher system voltages as well, but it becomes gradually less relevant when the system voltage increases. This document will be finalized in May 2009.

This new CIGRE working group, with participation of several Cired experts, is proposed in order to accomplish additional, important activity focused onLVnetworks, through the following proposed scope of work:

  • to document a careful review of the characteristics of lightning overvoltages (amplitudes, shapes, etc.) of different origins (cloud-to-cloud and intra-cloud lightning, indirect lightning, direct strikes to the low voltage conductors, direct strikes to low voltage power installations, transference from the MV network) inLVnetworks;
  • to investigate the overvoltage characteristics as a function of line and lightning parameters, load frequency-dependent behaviour and distribution transformer representation;
  • to present specific methods of protectingLVnetworks and relevant equipment.



A technical report/ brochure providing guidelines for lightning protection ofLVnetworks.

Convener: A. Piantini (Brazil)