RPAS Corona surveys of high voltage powerline infrastructure

Using a CoroCAM 6D Solar Blind Corona Camera from UVirco, fitted to a Altura Zenith ATX8 multi-rotor RPAS from Aerialtronics, Aerial Vision Africa is able to conduct low cost and highly effective aerial surveys of high voltage overhead powerline and sub-station infrastructure.

High voltage lines are electrical lines that distribute power at high voltages. The maintenance of these lines is a risky job, which requires careful attention and caution. Power line maintenance involves examining the pylons, inspecting their insulators and detecting thermographic problems.

Inspection is currently performed from the ground or by helicopter. The difference is that line inspectors who work from the ground are required to climb posts to access the lines whilst inspectors using helicopters do not. Although inspection with helicopters is much faster and safer, the downside is that this method is much more expensive and sometimes restricted in terms of time to avoid disturbance.

Electrical discharges into air cause the formation of the corona phenomenon. The corona phenomenon is the fluorescence of air, the fluorescence signature is mainly in the UV range with a small portion in the visible blue range.

The discharges cause power loss and causes damage to surrounding hardware.

A discharge from high voltage hardware is an indicator of:     

• Pollution
• Damage
• Incorrect design / fault situation
• Poor installation and/or workmanship

Electrical discharge into air can occur on many HV equipment.i.e

• Generator windings
• Along power lines
• On insulators
• On transformer / substation switch gear

The UV light emitted by the fluorescence event is collected and overlaid onto the visible image. This allows the operator to not just see if a discharge is present, but also to see it's location.

Being able to detect and localise the discharge, caused by a fault situation, allows maintenance staff to identify the cause and effect the right corrective action.

Power lost = revenue lost

Damage = higher costs

Remotely Piloted Aircraft Systems (RPAS) provide a safe, low cost and easily deployable alternative to traditional methods. RPAS carry cameras that produce high resolution images as well as thermal images, are equipped with transmitters enabling sharing of the live footage, are easy to deploy and can fly to within a couple of meters of the lines. RPAS aided inspections can improve the quality and safety of inspection, increase the frequency of inspection and reduce the costs of inspection all at once.