Imaging of Electrical Trees in High Voltage Insulation

New methods of imaging and characterisation of electrical trees

more videos

Breakdown of electrical insulation materials in the high voltage electrical power system can occur, over the long term, as a result of development of “electrical trees” within the insulation materials.

As the age of existing power infrastructure begins to exceed its design life, reliability of such insulation and hence our power supplies becomes a major issue for society. Previously it has only been possible to observe these “electrical trees” in two dimensions in transparent model materials. 

The research has used a combination of X-ray Computed Tomography (XCT) and Serial Block Face Scanning Electron Microscopy (SBFSEM) methods to recreate the three dimensional structure of the electrical trees.  While these are beautiful structures their impact on the electrical power systems can be devastating.

Project aims

The techniques developed in this research allow the development of the “electrical tree” to be observed in three dimensions thus enabling a more detailed characterisation and understanding of the structure to be obtained.

By better understanding the growth of such defects we will be better able to manage existing network infrastructure and improve new equipment, providing more reliable lower cost electricity supplies.


We all depend on a reliable supply of electricity for our modern lifestyles yet give little thought to the mechanisms by which this useful and reliable power supply reaches our homes, offices and factories.

Operators of the electrical system need to understand how the various components of the system will fail so that they can replace items before catastrophic failure occurs but also minimise the cost to us, the customer, by using equipment for as long as possible.

By understanding in detail how the insulation materials within the system fail we hope to develop more reliable models of failure that provide better predictions for these companies.

Future development

The imaging techniques are being developed as tools. These will enable improved materials and designs of insulation systems to be developed in further research. They will also provide data for ageing models on which to base asset management decisions for existing plant.


  • R. Schurch, S. M. Rowland, R. S. Bradley and P. J. Withers. ‘Imaging and Analysis Techniques for Electrical Trees using X-ray computed tomography’, IEEE Transactions on Dielectrics and Electrical Insulation, Volume 21, Issue 1, pp.53-63 (2014), DOI: 10.1109/TDEI.2014.6740725

  • R. Schurch, S. M. Rowland, R. S. Bradley and P. J. Withers. “Comparison and Combination of Imaging Techniques for Three Dimensional Analysis of Electrical Trees”.  Accepted for publication in IEEE Transactions on Dielectrics and Electrical Insulation, (2014)


Academic staff: Prof Simon Rowland

Research students: Mr Roger Schurch

Please contact staff for further details of current research.



School of Materials: Dr Robert Bradley, Prof Phil Withers

Faculty of Life Sciences: Dr Tobias Starborg 


  • The Dielectrics and Electrical Insulation Society (IEEE-DEIS) Graduate Fellowship Award
  • CONICYT-Chile (Chilean Research Council)
  • EPSRC for the Manchester X-ray Imaging Facility
  • EPSRC for the Supergen HubNet project.
▲ Up to the top