APPLICATION NOTE – WIND MILLS | LPS & SPD
Application Note: Lightning protection & Surge protection requirement for Wind Turbines as per IEC 61400-24.
A windmill is a device that uses sails set on a spinning shaft to harness the energy of the wind. India's economy is growing rapidly and the utilization of regenerative energy is on a steady rise. IEC 61400-24: Lightning Protection of Wind Turbines is the basis for the solution.
There are two common challenges for windmills: they are much taller than the surrounding environment (100 m & above), and the concentration of electrical & electronic systems is confined in a small area.
Lightning Protection Zones (LPZ) in Windmill Systems
- LPZ O A: The area above the LPS installation (electric & magnetic field are maximum)
- LPZ O B: The area just below the external LPS covered by rolling sphere radius (first level of attenuation)
- LPZ 1: Entry point of power & signal cables from the windmill tower to the building (second level of attenuation)
- LPZ 2: Place where sensitive electronic equipment is located (final level of attenuation)
Shielding: Nacelle are made of metal which is a closed structure by itself to protect from radiated effects of lightning. Shielded cables shall be used with 360-degree bonding at entry & exit points connected to EBB (Equipotential Bonding Bar).
Earthing: "Global earthing" as explained in IS3043 latest edition (2018) shall be followed, including the structural steel reinforcement of the wind turbine with the earth grid surrounding the windmill & the building.
SPDs: Conducted surges are reduced below the withstanding level of equipment by using SPDs for power, data, and communication lines. Either Class I or Class I+II 3-phase SPD with 400/690 V compatible with minimum Iimp of 12.5 kA for TN-C system shall be employed in parallel at the main DB.
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