short spans at crossings or near offshore structures where there is a high risk from falling objects. Uraduct does not provide protection from damage due to fishing trawls or anchor drags.
Burial Protection Index has been adopted in recent times. This approach assesses the level of protection afforded by the site- specific soil conditions and the threat level posed by third party interactions such as fishing gear and ship’s anchors.
182.
The total estimates for cable protection in the East Anglia THREE site and offshore cable corridor are presented in Table 5.18.
Table 5.18 Cable protection requirements for the East Anglia THREE site and offshore cable corridor Protection location
Total area (m2) Cable crossings in the wind farm
Cable protection in interarray (10% of 550km) Cable protection for Interconnector Cable protection for HVAC export cable
Cable protection HVDC export cable offshore of closure depth (10% of 508km)
Cable protection HVDC export cable inshore of closure depth (2.5% of 112 km)
720
330000 126000 117000
304800 16800
5.4.11.7 Export and interconnection cables: cable type (e.g. HVDC or AC), diameter, insulation, armour, EMFs and heat generated
183. The offshore export cables transmit the electricity from the offshore substation(s) to the designated onshore landfall point at a higher voltage (known as the transmission or export voltage) than is used for the inter array cables.
184. The interconnection cables would link offshore converter stations within East Anglia THREE together, and would link the proposed East Anglia THREE and East Anglia ONE projects together at a higher voltage (known as the transmission or export voltage) than is used for the inter array cables. The interconnection of projects allows for redundancy in the system in case of failure on the export cable system of one of the projects. The cables would either be two HVAC cables or a pair of HVDC cables, subject to detail design and future technology developments.
185. Electro Magnetic Fields (EMF) would be minimised due to a balanced and screened three-core system, incorporating a metallic screen that cancels the electronic field.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 5 Description of the Development Page 43
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