Wind Farms - Earthing & Lightning Protection Using Copper Earthing Systems

By Chris Dodds on 23rd September, 2014

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Wind Farms.

Earthing & Lightning Protection.

A wind farm copper earthing system is designed for two different functions : to protect human beings and the components in case of power systems fault and to protect them in case of a lightning strike hitting the wind farm turbines and structure.

Wind turbines have a considerably high possibility of being struck by lightning during their lifetime. For this reason it is essential to give to the electrical current a low impedance path.

The main characteristics of an earthing system are :

* Ensure that living beings in the vicinity of the earthing system are not exposed to dangerous potentials
* Retain system voltages within reasonable limits in case of faults
* Provide a sufficiently low impedance

The main factors to be considered designing a normal copper earthing system are soil resistivity, level of lightning protection required and power system earth fault level. In the case of wind turbines the copper earthing system is designed to be independent from the soil condition.

Pictured : Damaged Wind Turbine - Image Via www.times.co.uk

Lowering Soil Resistivity - 2 Options, Bentonite & Marconite

Bentonite is a moisture retaining clay used as an earth electrode back-fill to help lower soil resistivity.

Marconite is a granulated electrically conductive aggregate which replaces sand in mixes with cement, thereby providing electrically conductive concrete. Electrodes (including copper earth rods) can be encased in Marconite mixture to greatly increase their surface area, lowering the resistance to earth.

In modern wind farms all the WTGs (Wind Turbine Generators) are interconnected with a copper cable buried directly in the ground. It is called a multi-earthed system, and it reduces step voltage to a tolerable level in order to protect living beings from injuries.

Equipotentialisation of turbines and surrounding soil by means of a meshed earthing system reduces step voltage to a tolerable level in order to protect living beings from injury. This is obtained by connecting the entire interconnected foundation earthing (all the steel reinforcement bars in the foundation) to the earth interconnection wires between the wind turbines.

Basically the copper cable coming from the nearest turbine through the trench is tied to the reinforcement bars of the foundation. It goes all around the lower and upper reinforcement, and than is bond to the same earthing bar of all the electrical components of the WTG, such as the MV medium voltage transformer and the switchgears.

Using this solution the soil conditions around the wind turbines and the resistance to remote earth of the earthing system are not a concern because all fault currents are handled by direct connections of known dimensions and lengths.

T&D are the largest UK stockist of AN Wallis Earthing and Lightning Protection equipment including copper earth tapes, earth bars, earth rods, earth plates and a complete range of couplers, driving studs and bosses. T&D provide ex stock delivery for copper earthing systems and products to UK and international wind farm and solar PV farms.  

Bare Copper Tape
Bare Aluminium Tape
PVC Covered Tape
Solid Circular Copper Conductor
Bare Stranded Copper Conductor
PVC Insulated Stranded Copper Conductor
Earth Rods
Earth Rod Clamps
Earth Rod Couplings
Earth Bars
Earth Inspection Pits & Housings
Earth Plates & Copper Lattice Mats
 

Earthing, Lightning & Overvoltage Protection - Wind Turbines

Category:  Earthing & Lightning Protection

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