go to top scroll for more


Projects: Projects for Investigator
Reference Number NIA_NGET0012
Title Induced voltages and currents on transmission overhead lines under NSI 4 working practices
Status Completed
Energy Categories Other Power and Storage Technologies(Electricity transmission and distribution) 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
National Grid Electricity Transmission
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 February 2014
End Date 01 June 2016
Duration 28 months
Total Grant Value £135,000
Industrial Sectors Power
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , National Grid Electricity Transmission (100.000%)
Web Site http://www.smarternetworks.org/project/NIA_NGET0012
Objectives The key objective of this project is to establish working practice requirements based on the application of innovative modelling techniques developed by Cardiff University. Production of a Induced Voltages and Currents progress report Production of a Safety Assessment progress report Production of a final report on Induced Currents and Voltages and safety practices on OHL transmission lines
Abstract Previous detailed calculations carried out by National Grid, led to the currently adopted drain earth requirements being applied to National Grid transmission towers and specified in the National Safety Instruction Guidance document NSI 4. Based on questions and feedback from field engineers and maintenance staff, the NSI 4 working group propose to reconsider some of the background assumptions and explore different approaches to re-assess maximum levels of induced currents and voltages which inform work practice on or near high voltage lines. Research The method that has been proposed for this project includes; Induced voltages and currents Calculate the maximum level of induced voltage (steady-state and switching transient) on a de-energised phase conductor of a 275kV and 400kV line when Drain Earths are applied at every 10th tower and with Primary Earths at both circuit ends. ALARP risk assessment Quantify the individual risk (IR) of electrocution, measured on the ALARP scale, when accessing terminal towers and taking into account missing or broken earth tapes between the substation main earth grid and the tower. The IR will be determined for scenarios such as climbing the tower to apply drain earths* and if a significant risk is found an evaluation will be made to determine whether the risk can be controlled to acceptable levels by limiting the time spent in the vicinity of the tower*. The IR will be calculated for both steady-state and fault (EPR) conditions.Note : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above
Publications (none)
Final Report (none)
Added to Database 20/08/18