For bulk power transmission, in addition to using higher voltages, higher ampacity is equally necessary. To meet this need, use of conductor with higher cross-sections is imminent. For conductor sizes below 1000 sq mm, compact circular stranded conductor construction is suitable. However, for conductor sizes above 1000 sq mm, use of segmental conductor construction (also called Milliken conductor) is recommended to overcome the skin effect. CCI has the technology to manufacture such segmental conductors.

Cable Corporation of India Ltd. Offers two distinct technologies, both employing dry curing systems for the production of XLPE insulated cables. The extruded core in the Continuous Catenary Vulcanising (CCV) line is subject to gravitational force which poses limitations in handling cores having a larger weight to length ratio. Difficulties, therefore, can be encountered with finished cores which many not have a fully concentric shape after cross-linking particularly for large cross-sections, thereby resulting in installation and jointing problems. In view of this, for very high electrical stress levels (as observed in EHV) and for large corss-sections, the conventional CCV line may not be adequate. It is for this reason that CCI has adopted a special patented MDCV process exclusively for manufacturing EHV cables.

CCI under licence from Mitsubishi Petrochemical Company Ltd., Japan has set up the plant called the Mitsubishi Dainichi Continuous Vulcanising (MDCV) line for EHV cables, which is the first of its kind in Asia, outside Japan. The heart of the system is a unique Long Land Die (LLD), inside which cross-linking is carried out under specially controlled conditions. Because of its capacity to handle heavier and larger cores, the MDCV process is known worldwide for making high-quality XLPE cables even upto 400-500 kV range, with no limitations of conductor size upto 2000 sq.mm. With this technology, CCI has joined a select group of international manufacturers in the field of super tension XLPE cables.

Unique features of the MDCV Process

1) The plant has a horizontal layout, as a result of which the conductor as well as the extruded core can remain in a straight line without bending or sagging, thereby permitting stabilised manufacture of large-sized cables.

2) Cross-linking in Long Land Die under strict process control employing dry curing at elevated temperatures, ensures void-free, homogeneous insulation.

3) Simultaneous extrusion of conductor screen, insulation and insulation screen in one single operation ensures perfect bonding without any surface irregularities.

4) Further perfection is achieved by the use of special techniques which constitute the hallmark of the process. The conductor and insulation (core) is fully supported in the LLD, and as such, the tendency of the core to sag is avoided inside the straight and horizontal LLD.

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