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. Windmills, Solar PV & bio-gas plants are becoming popular day by day.
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.
The electrical & electronic system includes switchgear cabinets, motors, drives, frequency converters, actuators, sensors, control electronics including communication bus systems employing Modbus or Profibus protocol via RS 485 physical layer.
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 where electric & magnetic fields are very minimum)
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) on either side of the cable.
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: While radiated surges are limited by shielding technique, 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.
Please let us know if you need further assistance or have any requirements: [email protected]
