The three-year project, which is funded by Ofgem’s Network Innovation Allowance, could save time and cost compared with traditional ground patrols.

Insulators are often made of glass or ceramic and protect pylons from the current on the power line to prevent the tower becoming live. They produce electric fields when in operation, which have distinct profiles that are altered by defects on the insulator.

A purpose-built electric field sensor system can be flown by drone near to a pylon to analyse the insulators’ e-field profiles and assess their health, without the need for circuit outages, lineworkers scaling pylons, or insulator samples being sent for forensic analysis.

National Grid estimates that the initiative could save £2.8m over a 15-year period through cost and resource efficiencies in transmission network monitoring.

The technology will be developed and tested in the University of Manchester’s high-voltage laboratory, which has been the testbed...