STRUCTURE OF 33 KV CABLES
Normally 33kv cable is a kind of mv cables. It alludes to one center 33kv xlpe cable with aluminum wire shield (AWA) three centers 33kv underground cable with steel wire reinforcement (SWA) layer. The layers give very well mechanical security when established. The 33kv cable intended for power dispersion arrangement and appropriate for direct internment. The 33kv underground cable is very suitable for huge venture. For example, building, underground mining mine, capacity substation, railroad etc. 3 Core 33kv underground cable with flame resistant (LSZH).
33kv Cable consists of (in to out) – an aluminum conductor separator, conductor screen, XLPE insulation, a metallic screen (optional) separating it from the outer sheath and an insulation screen attached to a support conductor.
Core 33kv cable used for underground
The inner core has a solid aluminium or stranded copper conductor covered by semi conducting conductor screen, XLPE insulation, semi conducting insulation screen, water swellable tape and MDPE sheath covering a copper wire screen that is wounded with copper.
Core 33kv underground cable with fire resistant(LSZH)
Inner core- stranded copper conductor, semi conducting conductor screen, XLPE insulation, semi conducting insulation screen, copper tape screen and PETP fibres filler.
Outer core- these are further covered by copper tape screen, LSZH bedding, aluminium/steel wire armour and LSZH sheath.
ASPECTS OF 33 KVCABLES
Intended for power dissemination systems and reasonable for direct internment, they are accessible as single center cables or three-center cables, with aluminum wire defensive layer (AWA) and steel wire covering (SWA) separately giving mechanical security. These cables are intended for successfully earthed nonpartisan system. The Cables may likewise be laid inside secured cable channels, in cable racks or outside stepping stool plate and so on for specific bits of lengths. Underground Cable is to be fabricated in persistent catenary process at controlled raised temperature and weight in idle environment with utilization of appropriate materials for XLPE fundamental protection and XLPE semi-leading Insulation and XLPE screen.
The XLPE Cable in this determination does not have any metal sheath and the short out rating of the cable will rely upon the conductivity and coherence of the strands of the defensive layer wires which will be guaranteed for guarding against consumption.Blend of dark expelled semi-leading compound and semi-directing tape as the nonmetallic part and toughened copper tape lapping as metallic part metal screen disposes of unrelated worry of turning electrostatic field encompassing the conveyor and uniform electrical worry in the protection. Metal copper screen ought to have the option to convey a short out current of 1KA for 1 sec.The semi-leading polyethylene (XLPE) screen will be expelled over the principle polyethylene protecting divider to avert. Incomplete release at the outside for protection. The copper tape will be folded around the semi leading tape or expulsion as referred before for 3 center cables. The metal screen conformed to the centers will be in contact with each other as the centers are laid up at triangular setup.
For single center cable, aluminum wire armouring will establish the metallic piece of protection screen. Conductor screening, protection and protection screening will be expelled in triple expulsion process to acquire persistent smooth interfaces. The mechanical and compound properties of the materials for semi directing screens are considerably more significant than their electrical properties, however for acquiring the high in general level of electrical properties of a H.V. cable, the internal and external semi leading screens and the primary polyethylene protection between the screens will be at the same time expelled amid the assembling procedure known as “tripple expulsion”.
INNER SHEATH : The cable center will be provided with bedding of PVC (inward sheath) as expelled PVC Type ST-2 compound for 33 KV. For single center cable inward sheath isn’t required.
ARMOR : Galvanized round steel wires or aroused shaped wires for 3 center cable. Single layer of round hard drawn aluminum wire for 1 center cable to guarantee a satisfactory return way for the progression of issue current and furthermore to give appropriate mechanical assurance. For 1 center aluminum Wires of required size in essential number will be laid intently in the winding arrangement to ensure the outline of the cable completely and to give satisfactory cross sectional region to stream of most extreme issue current inside cutoff points of indicated temperature rise and term of issue. The bearing of the lay of the reinforcement will be inverse to that of the cable centers.
OUTER SHEATH : A solid serving will be vital for keeping up conductivity of the covering especially under destructive condition as coat. The cable will be done with an expelled PVC over sheath of thickness. The nature of PVC over sheath (Jacket) will be guaranteed for administration dependability against dampness interruption . The sheaths will be secured against white ants, vermin and termites by reasonable, dependable and tough measures. The cable ends in the wooden drum for conveyance will be fixed with warm shrinkable tops.