Long Term Stability Testing of Alternative Gases

Completed

Other Power and Storage Technologies(Electricity transmission and distribution)

Applied Research and Development

PHYSICAL SCIENCES AND MATHEMATICS (Chemistry)
ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering)
ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering)

Not Cross-cutting

Project Contact
National Grid Electricity Transmission

Network Innovation Allowance

Ofgem

01 January 2018

30 April 2020

ENA months

£353,000

Power

London

Network Innovation Allowance

Project Contact, National Grid Electricity Transmission

Project Contact, National Grid plc

A specialist stainless test rig will be used to conduct the tests. First, the effect of discharges and flashover in the gas mixtures will be measured in terms of by-products. Both short term and long term tests will be explored. An in-house technique employing a GCMS system will be used to analyze the gas by-products following incremental periods of time of discharges and number flashover events. A list of by-products will be developed for each mixtures tested in this programme and its correlation with severity of electrical discharge activity will be quantified. Furthermore, for the above tests, comparison of Novec gas with its various mixtures with CO2 and/or N2 will be conducted (at 100%, 50%, 20%, and 4%). This will work will help to indicate if any health and safety studies of the gas mixtures are required.The second major axis this work is to investigate the stability of the gas and its mixtures. Building on the previous work of by-product analysis, quantifying the impact of the gas and its mixtures on the surrounding materials will be necessary to determine the long term stability of the gas. In this case, various materials used in GIS technologies will be sourced (through National Grid) and investigated. Existing methods of life estimation for dielectrics will be considered and adapted for the gas mixtures in the presence of various materials and under various diverging electric field conditions. This work will determine the overall stability of the gas mixtures, their life expectancy and their reaction with the surrounding materials. Scanning electron microscopes (SEM) will be used to investigate the changes of surface properties of the various materials. This will form a solid platform for future detailed analysis of the gas long term stability, if required. This project will focus on health and safety of the new gas mixtures based on the NOVEC gas. It will also give an initial indication of the gas mixtures stability and their interaction with the surrounding environment and materials. Gas by-products, due to varying levels of electrical discharge in the gas mixtures, will be analyzed by adopting a Cardiff in-house technique using a GCMS system. The interaction with surrounding material will be examined through surface analysis using SEM techniques. The ultimate aim of this work is to gain a better understanding of the recently proposed alternative gases and gas mixtures to replace SF6 gas. This will reduce the environmental impact of the transmission network.The particular objectives of this work are to:Determine the impact of electrical discharges and flashover on the dielectric properties of the gas mixturesDetermine the by-products of the gas mixtures following flashoverDetermine the impact of the gas mixtures and their by-products on surrounding materials.Determine an indicator of gas mixture degradation and estimate long term stability.

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09/11/22