LM DiverterStrips – conduct lightning away

LM DiverterStrips increase the area of the blade designed for intercepting the strike. This is particularly relevant as blade designs are constantly getting longer and thus wider. LM DiverterStrips are also incorporated as an important part of our protection system for carbon fibre blades, which feature particularly stringent requirements regarding lightning protection.

The intelligent wind turbine blades of the future – with built-in electronic equipment for blade monitoring, for example – are also quite demanding in terms of the need for reliable lightning protection. LM DiverterStrips are very suitable for increasing the area that intercepts lightning strikes on these blades.

 

Antennas conduct the lightning

LM DiverterStrips act as lightning antennas. Small pieces of metal fitted on these strips create a channel of ionised air that conducts the lightning to the receptor.

Other methods use a metal rail or net placed under the blade’s outer layer of paint or gelcoat. However, the new LM Glasfiber system intercepts the lightning strikes on the surface itself. This prevents lightning from damaging the blade’s surface and outer layers of laminate – a distinct advantage in comparison with protection systems mounted beneath the surface. It also does away with the need for service inspections and repairs, and the high costs associated with both service and downtime in electricity production, particularly for offshore wind farms.

Well-proven technology used in new ways

Diverter strips have been used for a number of years to protect the radar dome mounted on aircraft. This dome is made of glass fibre to make sure that the digital signals from the radar can penetrate the material unimpeded. When the dome also houses instruments that are crucial for controlling the aircraft, it is extremely important that this part of the aircraft is protected from lightning strikes. Numerous detailed tests have therefore been carried out on diverter strips and their ability to channel lightning as required.

The kinds of diverter strips used in aviation need to be modified for use in protecting wind turbine blades, as they are designed to be replaced after just one or two lightning strikes.

The development of diverter strips for wind turbine blades has therefore involved completely new principles.

LM DiverterStrips are designed to be as aerodynamic as possible, to limit any effects on the blade’s performance and noise levels.  LM DiverterStrips are also easy to mount on the blade, both during production and as a retrofit, if required.

These specially designed diverter strips already make up an important part of the lightning protection on the world’s longest mass-produced wind turbine blades – the LM 61.5 P blades – fitted on the prototype REpower 5 MW wind turbine in Northern Germany.
More about the world’s longest mass-produced blades