Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
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Cable types <strong>and</strong> installation techniques<br />
High voltage direct current (HVDC) is not economically viable at present due to<br />
the high cost <strong>of</strong> HVDC converters, however it may, in the future, be used for sites<br />
situated further <strong>of</strong>fshore.<br />
The current <strong>and</strong> future generation <strong>of</strong> export cables are likely to be rated with<br />
a voltage <strong>of</strong> 132kV. The cable is likely to be constructed with 3 core copper<br />
conductors, insulation <strong>and</strong> conductor screening, steel wire armour <strong>and</strong> either<br />
ERP or XLPE insulation with a lead sheath. The copper conductor size is typically<br />
estimated at between 300mm 2 <strong>and</strong> 1200mm 2 . The cables will contain optical<br />
fibres embedded between the cores for data transmission <strong>and</strong> communications.<br />
The range <strong>of</strong> indicative cable conductor sizes <strong>and</strong> overall dimensions which<br />
could be used for a 132kV export cable for an <strong>of</strong>fshore wind farm are shown in<br />
Table 3.1.<br />
Table 3.1: Typical Cable Characteristics For 132kv Cable<br />
Details 132kV Cable Type<br />
300 mm² 500 mm² 800 mm² 1000 mm² 1200 mm²<br />
Overall Diameter (mm) 185 193 214 227 232<br />
Weight (kg/m) 58 68 88 100 108<br />
MVA (approx) 127 157 187 200 233<br />
3.3.3 INTER-TURBINE ARRAY CABLES<br />
The inter-turbine array cables are the cables which connect the <strong>of</strong>fshore turbines<br />
into arrays <strong>and</strong> also connect the various arrays together. It is normal practice<br />
to cable several turbines together in an array, with each cable providing a link<br />
between two adjacent turbines. Each end <strong>of</strong> the cable is terminated onto the<br />
high voltage (HV) switchgear located within the turbine tower. Because they<br />
connect to the HV switchgear at the turbines, the operating voltage for the<br />
inter-turbine cables is limited to 36kV. These cables would also connect any<br />
<strong>of</strong>fshore substation to the <strong>of</strong>fshore WTG arrays. The cables between WTGs are<br />
relatively short in length (typically in the range 500m to 950m). However, the<br />
cables between the <strong>of</strong>fshore substation <strong>and</strong> the WTG arrays could be longer <strong>and</strong><br />
possibly up to 3.0km.<br />
The inter-turbine array cables will typically be 33kV, 3-core copper conductors<br />
with insulation/conductor screening <strong>and</strong> steel wire armoured. The insulation<br />
will be either dry type XLPE, wet type XLPE or a combination <strong>of</strong> both. All cables<br />
will contain optical fibres embedded between the cores. A number <strong>of</strong> conductor<br />
sizes would be used depending on the load current that the cable is required to<br />
carry. The ranges <strong>of</strong> indicative cable conductor sizes <strong>and</strong> overall diameters that<br />
may be used are shown in Table 3.2.<br />
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