86. Magnetic fields are produced by the current within a conductor. The current varies according to the electrical power requirement. The higher the current the stronger the magnetic field that is produced. Microteslas (μT) are the unit of measurement used for magnetic fields. In the UK, the Earth has a natural magnetic field of approximately 50μT.


87. In contrast with electric fields, magnetic fields are not readily screened by trees and


ordinary building materials. However, they diminish rapidly with distance from the source. The proposed East Anglia THREE project comprises underground HVDC cables from the landfall near Bawdsey to the converter station at Bramford. At the converter station, HVDC would be converted to three-phase AC for connection to the National Grid Electricity Transmission System (NGETS).


88. The converter station would be connected to the existing National Grid substation at


Bramford by means of up to two buried AC cables. These may be installed directly underground or within ducts.


22.6 Potential Impacts Reference should be made to Chapter 5 Description of the Development, for full


89.


details of the activities proposed during the construction phase. However, in summary, the activities considered likely to impact on land use and agriculture are as follows:


90.


Scenario 1 – ducts for the proposed East Anglia THREE and East Anglia FOUR projects would be pre-installed during construction of the East Anglia ONE project


 Construction of onshore cable systems including landfall joint transition bay and 48 cable jointing locations – installation techniques include pulling cables through existing ducts;


 Construction of an onshore converter station, associated infrastructure and landscaping;


 Creation of temporary construction compounds / HDD compound;


 Temporary upgrade of existing access tracks, construction of new access tracks and haul roads;


 Stockpiling of topsoil and subsoil;  Re-use of excavated soil in jointing pits;  Disposal of excess spoil offsite to a suitably licenced facility; and  Removal and reinstatement of existing drainage systems.


Preliminary Environmental Information May 2014


East Anglia THREE Offshore Windfarm


Chapter 22 Land Use Page 34


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