66KV HV CABLES
The application of 66kV Power Cable has gained importance mainly due to urbanisation. To transport power to load centers of metropolitan cities and satellite towns underground 66kV XLPE Power Cables are being heavily favored due to non-availability of Sand for constructing overhead transmission towers. The need for 66kV
XLPE Power Cables has become essential due to the following constraints:
- Protracted Land Acquisition procedures and litigation problems
- Increasing ecological restriction
- Soaring cost of real estate.
There are two kinds of 66kV XLPE cables:
- HV Cables
- MV Cables
World-wide High Voltage and Medium Voltage XLPE Cables have rapidly replaced the conventional Oil-Impregnated-Paper Insulated Cables and Gas-Filled Cables for the following distinct advantages:
- Higher Power Transmission Capacity
- Lower Dielectric Losses
- Maintenance Freedom
- Independence of route profile and terrain
- Easier jointing and termination
- Lower installation cost
- No environmental hazard
Nicco's XLPE Cables are manufactured with the latest state-of-the-art technology of Triple Extrusion using Single (Common) Cross Head Extrusion technique and Dry Cure (Inert Gas Cured) Cross-linking Process, which has the following noteworthy features and characteristics:
- No irregularities eg. protrusions, disruptions, asperities in the inner and outer
- Uniform 3 layer insulation structure
- Free from Micro Voids and Moisture Content
Nicco s 66 kV XLPE Cables of various sizes have been successfully Type Tested at Central Power Research Institute (CPRI), Bangalore.
66Kv MV Cables
XLPE is an abbreviation of Cross-Linked Polyethylene. This has been recognised worldwide as an excellent dielectric for wires and cables. It first went into commercial production in 1960. Polyethylene which is a thermoplastic material is converted into a thermosetting material by a process similar to vulcanisation of rubber. By crosslinking, the linear chain structure of polyethylene is changed into three-dimensional network structure. By this change, polyethylene which has outstanding dielectric properties is made resistant to extremes of temperature. The high resistance to heat deformation and ageing in hot air provide important advantage in cable ratings and is of special significance at locations where the ambient temperature is high. These, along with better resistance to environmental stress cracking and low dielectric constant make XLPE Cables particularly suitable for high voltage applications.
A Few striking features of XLPE Cables :
High Continuous Current Ratings : Higher continuous operating temperature of 90°C for conductor permits XLPE Cables to withstand higher current ratings than PVC or PILC Cables.
High Short Circuit Ratings : Maximum allowable continuous temperature during short circuit is 250oC, which is vastly increased as compared to PVC or PILC Cables.
Little Deformation at High Temperature : Under combined heat and mechanical pressure XLPE suffers less deformation compared to other solid dielectrics.
High Emergency Load Capacity : XLPE cables can be operated at 130°C during emergency. This should not exceed 2 hours a day, 1 00 hrs. per year or 500 hrs. during the lifetime of the cable. Due to this 20% higher current than the specific rating may be carried for this period.
Low Dielectric Loss : The dielectric loss angle of XLPE is much lower than conventional dielectric. The dielectric losses are quadratically dependent on the voltage. Hence use of XLPE Cables at higher voltages would generate considerable saving in costs.
Low Charging Currents : The charging currents are considerably lower than other dielectrics. This permits close setting of protection relays.
Lighter Weight : XLPE Cables are easier to handle because of its lightweight. The small bending radii makes laying and installation of cables very easy.