NEW TECHNOLOGIES USED IN THE MAINTAINENCES OF UDERGROUND CABLES

[seminar class]

Presented by
B.NAGA RAJU

---

[attachment=11937]
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.