Nov 2018
Electricity Transmission
High Frequency Earthing and its Impact on the Transmission System
Nov 2018
Dec 2020
National Grid Electricity Transmission
Linwei Chen
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Network Innovation Allowance
ET - Safety and health and environment
Given that High Frequency (HF) rods are more susceptible to installation difficulties and higher costs, there would be strong saving benefits if the need for HF rods can be avoided. Furthermore, early research at Cardiff demonstrated the superiority of HF performance of partially insulated electrode configurations overlaid on existing earth grids. Such a solution, if adopted, can help mitigate the effect of high frequency and surge currents more effectively and with associated cost savings on installation and maintenance. This project will involve extensive modelling and experimental testing to investigate the safety issues and the effectiveness of high frequency earth electrodes with various earthing methods.
The main objectives of this project are to:

  • Fully quantify any added benefit of the so-called High Frequency rod and assess its cost benefits.
  • Fully quantify the earthing down lead geometries and arrangements on the effectiveness of the earth electrode and earth potential rise under high frequency fault currents and surges on the system.
  • Further develop, refine and quantify the benefits of the Cardiff University proposed alternative method of overlaid insulated horizontal conductors for reducing earth impedance, improving the effective area of earthing systems and enhancing the high frequency earthing performance. Furthermore, establish the relative merit of this technique compared to HF rods.
  • Trial and validate test new techniques for earth impedance measurements under high frequency and surge conditions.