09-04-2011, 03:09 PM
Presented by
B.NAGA RAJU
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NEW TECHNOLOGIES USED IN THE MAINTAINENCES OF UDERGROUND CABLES
BACK GROUND OF CABLES
Some of the more common early solid and liquid insulating materials employed in various underground cable installations were natural rubber, gutta-percha, oil and wax, rosin and asphalt, jute, hemp, and cotton.
The operating voltage range to 35 kv, due to non-uniform stress distribution in the cable construction.
This cables cann’t satisfies minimum requirement of more dielectric ,aging of cables and effient power transfer cabilities.
IMPACT OF UNDERGROUND CABLES IN EXISTING NETWORKS
Integration of new cable system needs detailled planning
Quicker realization of networkextansion
There might be compensationsystems needed at length longer than 20 km
• New technologies of under ground cables
New technologies of under ground cables
• CROSS- LINKED POLY ETHYLENE(XPLE)
• TREE RETARDANT ACROSS-LINKED POLYENTHYENE(TR-XPLE)
• SUPERCONDUCTOR CABLES
• REAL TIME THERMAL RATING(RTTR)
• ELECTROMAGNETIC SHIELDING
CROSS- LINKED POLY ETHYLENE(XPLE)
• The cross-linked polyethylene (XLPE) underground transmission line is often called “soliddi electric”.
• This type of line relies on high-quality manufacturing controls to eliminate any contaminantsor voids in the insulation that could lead to electrical discharges and breakdown of the line from electrical stress
• The solid dielectric material replaces the pressurized liquid or gas of other types of cable. The below Figure illustrates the XLPE in cross-section.
• They are not housed together in a pipe, but are set in concrete ducts or buried side-by-side directly in specially prepared soil.
• The insulation is about twice as thick as the oil insulation used in other types of cable
While all previous installations are AC applications, applying the technology to DC is straightforward.
TREE RETARDANT ACROSS-LINKED POLYENTHYENE(TR-XPLE)
The use of tree retardant XLPE insulation has allowed utilities to achieve long service life under severe operating conditions.
This has led to improved life cycle economics and has minimized social and environmental issues resulting from cable replacement activities.
XLPE and other polymers, undergo a degradation process, called water treeing, when exposed to moisture and an electrical stress.
Tree-retardant crosslinked polyethylene (TR-XLPE) was designed to overcome the water treeing deficiency of high molecular weight thermoplastic polyethylene and crosslinked polyethylene (XLPE)
TR-XLPE was designed to maintain XLPE’s high dielectric strength and low electrical loss.
SUPERCONDUCTOR CABLES
Superconductor cables utilize superconductor materials instead of the copper or aluminum traditionally used to carry electricity in underground cables.
Superconductor materials can carry well over 100 times the current density of copper or aluminum
when transmitting DC power, superconductors become perfect conductors with zero electrical resistance and introduce no electrical losses of their own.
Superconductor cable systems are now operating in multiple in-gridsites around the world, demonstrating their reliability and performance, as illustrated in Figure 1
While all previous installations are AC applications, applying the technology to DC is straightforward.