This project successfully trialled Mobile Asset Assessment Vehicles (MAAV) in the central London area, which contains over 2,000km of LV underground cables along with joints. The MAAV assessed all accessible road surfaces in the survey for the presence of contact voltage faults from buried cables and accessories.
The aims of the project were to:
The first survey aimed to cover all accessible carriageways in the central London Area. The “centreline distance” of the carriageways is approximately 926km and the MAAV systems drove over 1800km during each assessment. Any object or surface which was energised at more than 1V AC was recorded and investigated.
The second survey included the same coverage of the central London area using the MAAV approximately 4 to 6 months following the completion of the first survey. The second survey identified newly generated contact voltage faults, which was used to understand the generation rate of these types of faults in the area.
The data collected was analysed after each survey to provide a better understanding of the performance, behaviour and health of the central London network. The analysis included an assessment of the underlying types of faults present, the root causes of the failures and the generation rate of new faults.
Contact voltage surveys had only once been trialled in the UK with a previous generation of the
The impact that system design differences may have on the efficacy of the testing using current technology in the UK was unknown until MAAV was completed. As an example many US cities use unshielded LV cables which are installed in underground ducts, while the vast majority of LV cable in the UK is shielded and directly buried.