Weybridge to Byfleet

The brief

The client approached BPI to undertake a high accuracy thermal uprating study for an existing overhead line crossing a number of houses and adjacent features.  The overhead line comprised ten spans connecting two major substations.  With limited information on the overhead line available to undertake the uprating study, BPI’s in house survey team completed an onsite high accuracy survey of the underlying features with multiple observations of the existing conductor system.

The approach

BPI produced a detailed scope of work and methodology to produce a high accuracy onsite survey using the latest remote sensing theodolites.  Using specialist overhead line design software, the survey data was post-processed into a detailed 3D CAD model.  This accurately modelled the conductor middle and bottom phases in still air and swing conditions based on the conductor electrical rating on the day of the field survey.  We provided options to improve the thermal rating of the conductor with minimal increase in sag, including a replacement high temperature conductor and a new conductor insulator system.

The challenges

This particular project required a high accuracy ground survey with 3D post-processing techniques using the latest overhead design software.  As it was in a built-up residential area we had to work closely with the client and installation contractor to determine compliant constructible line modifications to achieve the required line rating.

The delivery

BPI completed the site survey and produced a number of detailed design options.  Further discussions were held with the installation contractor to provide a solution which could be installed on site with minimal circuit outage times and temporary protection.  A comprehensive report was produced providing the increased capacity of the line and the various clearances at different operating temperatures.