Claims:Claims
What is claimed is:
1. A power cable assembly comprising:
a power cable, the power cable comprises:
a core assembly, wherein the core assembly comprises one or three electrical conductor units lying substantially along a longitudinal axis of the power cable assembly, each electrical conductor unit of the one or three conductor units is stranded together, wherein the one or three electrical conductor units comprises:
an electrical conductor, wherein the electrical conductor is made of at least one of aluminium and copper, wherein the electrical conductor has a diameter in a range of about 16.2 millimeters - 37.5 millimeters;
a conductor screening layer surrounding the electrical conductor for screening the electrical conductor, wherein the conductor screening layer is formed of semiconducting compound suitable for continuous operating temperature of 90 degree Celsius, wherein the conductor screening layer has a diameter in a range of about 24.5 millimeters - 24.7 millimeters and a thickness of at least 0.2 millimeter;
an insulation layer surrounding the conductor screening layer, wherein the insulation layer is made of cross-linked polyethylene enabling the power cable assembly to operate continuously at a temperature of about 90 degree Celsius, wherein the insulation layer has a diameter in a range of about 31.9 millimeters – 32.1 millimeters and a thickness in a range of about 3.14 millimeters to 8.8 millimeters;
an insulation screening layer surrounding the insulation layer, wherein the insulation screening layer is formed of semiconducting compound suitable for continuous operating temperature of about 90 degree Celsius, wherein the insulation screening layer has a diameter in a range of about 33.1 millimeters – 33.3 millimeters and a thickness of at least 0.2 millimeter;
a metallic screening layer surrounding the insulation screening layer, wherein the metallic screening layer is made of at least one of copper tape and copper wire and wherein the metallic screening layer has a diameter in a range of about 33.9 millimeters – 34.1 millimeters and a thickness of at least 0.045 millimeter;
a sheathing assembly, wherein the sheathing assembly surrounds the core assembly, wherein the sheathing assembly comprises:
a first layer surrounding the core assembly, wherein the first layer is made of at least one of polyvinyl chloride and polyethylene, wherein the first layer has a diameter in a range of about 74.1 millimeters – 74.3 millimeters and wherein the first layer has a thickness of at least 0.7 millimeter;
a second layer surrounding the first layer, wherein the second layer is an armoring layer made of galvanized steel wire and wherein the second layer has a diameter in a range of about 82.1 millimeters – 82.3 millimeters;
a third layer surrounding the second layer, wherein the third layer is made of polyethylene, wherein the third layer has a diameter in a range of about 90.5 millimeters – 90.7 millimeters and wherein the third layer has a thickness of at least 3.0 millimeters; and
a conduit surrounding the sheathing assembly, wherein the conduit is made of polyethylene and wherein the conduit has a diameter in a range of about 95.4 millimeters – 95.6 millimeters and wherein the conduit has a thickness of at least 2.0 millimeters.
2. The power cable assembly as recited in claim 1, further comprising a binder tape disposed between the second layer and the third layer, wherein the binder tape being made of at least one of rubberized cotton tape and polyvinyl chloride tape.
3. The power cable assembly as recited in claim 1, further comprising a semi-conducting water blocking tape layer disposed between the insulation screening layer and the metallic screening layer.
4. The power cable assembly as recited in claim 1, wherein the second layer has a nominal thickness of about 4.0 millimeters.
5. The power cable assembly as recited in claim 1, further comprising first filler positioned at a center of the core assembly and substantially along the longitudinal axis of the power cable assembly, wherein the first filler is made of a material selected from a group consisting of polypropylene, polyethylene and polyvinyl chloride and wherein the first filler has a diameter in a range of about 4.1 – 7.4 millimeters.
6. The power cable assembly as recited in claim 1, further comprising one or more second fillers positioned inside the core assembly and substantially along the longitudinal axis of the power cable assembly, wherein each of the one or more second fillers is made of a material selected from a group consisting of polypropylene, polyethylene and polyvinyl chloride and wherein each of the one or more second fillers has a diameter in a range of about 12.5 – 22.1 millimeters.
7. The power cable assembly as recited in claim 1, further comprising one or more third fillers positioned inside the core assembly and substantially along the longitudinal axis of the power cable assembly, wherein each of the one or more third fillers is made of a material selected from a group consisting of polypropylene, polyethylene and polyvinyl chloride and wherein each of the one or more third fillers has a diameter in a range of about 6.2 – 11 millimeters.
8. The power cable assembly as recited in claim 1, further comprising an optical fiber cable unit positioned in one or more interstitial spaces between the one or three electrical conductor units and the first layer of the sheathing assembly.
9. The power cable assembly as recited in claim 1, wherein the power cable has a pre-defined voltage rating in a range of about 11 kilovolts to 33 kilovolts.
10. The power cable assembly as recited in claim 1, wherein the electrical conductor has a pre-defined cross-sectional diameter of at least one of 185 square millimeters, 240 square millimeters, 300 square millimeters, 400 square millimeters and 500 square millimeters.

, Description:POWER CABLE ASSEMBLY
TECHNICAL FIELD
[0001] The present disclosure relates to the field of electrical cables. More particularly, the present disclosure relates to a power cable assembly for underground applications.
BACKGROUND
[0002] Power cables are employed for transmission and distribution of electrical power in rural, suburban and urban areas. These power cables are characterized as low voltage cables, medium voltage cables and high voltage cables. These power cables are installed underground in ducts by open trenching method or trenchless method based on a type of location. Traditionally, these underground installed power cables are prone to faults due to damage. The faults may occur at any location along the length of the power cable. These faults are detected and the location is pin pointed by using a surge generator or thumping method which provides information related to the location where the fault has occurred.
[0003] The current design of these power cables installed in ducts by horizontal directional drilling method poses issues in the process of detection of the location of the fault. These power cables are placed loosely inside the duct which leaves an air gap or free space between the cable and the duct. The air gap or the free space between the cable and the duct leads to an echo effect. The attenuated noise gets distorted due to the echo effect which makes it difficult to pin point the exact location of the fault. This leads to loss of valuable time and increase in effort for pin pointing the exact location. In addition, this leads to loss in revenue and end customer dissatisfaction. Further, the use of pipes or ducts for installing the power cables leads to a decrease in a current carrying capacity of these power cables. Specifically, the use of pipes leads to de-rating of the power cables. Furthermore, there is an issue of requirement of space when the power cables are installed underground.
[0004] In light of the foregoing discussion, there exists a need for power cable design which overcomes the above cited drawbacks of conventionally known power cable designs installed in ducts by horizontal directional drilling method.
SUMMARY
[0005] In an aspect, the present disclosure provides a power cable assembly. The power cable assembly includes a power cable and a conduit. The power cable includes a core assembly. The core assembly includes one or three electrical conductor units. The one or three electrical conductor units lie substantially along a longitudinal axis of the power cable assembly. Each electrical conductor unit of the one or three conductor units are stranded together. In addition, the power cable includes a sheathing assembly. The sheathing assembly surrounds the core assembly. Moreover, the power cable assembly includes the conduit. The conduit surrounds the sheathing assembly. The one or three electrical conductor units include an electrical conductor. In addition, the electrical conductor units include a conductor screening layer. The conductor screening layer surrounds the electrical conductor. The conductor screening layer screens the electrical conductor. Moreover, the electrical conductor units include an insulation layer. The insulation layer surrounds the conductor screening layer. Further, the electrical conductor units include an insulation screening layer. The insulation screening layer surrounds the insulation layer. Also, the electrical conductor units include a metallic screening layer. The metallic screening layer surrounds the semi-conducting water blocking tape layer. The sheathing assembly includes a first layer. The first layer surrounds the core assembly. In addition, the sheathing assembly includes a second layer. The second layer surrounds the first layer. Further, the sheathing assembly includes a third layer. The third layer surrounds the second layer.
STATEMENT OF THE DISCLOSURE
[0006] The present disclosure relates to a power cable assembly. The power cable assembly includes a power cable and a conduit. The power cable includes a core assembly. The core assembly includes one or three electrical conductor units. The one or three electrical conductor units lie substantially along a longitudinal axis of the power cable assembly. Each electrical conductor unit of the one or three conductor units are stranded together. In addition, the power cable includes a sheathing assembly. The sheathing assembly surrounds the core assembly. Moreover, the power cable assembly includes the conduit. The conduit surrounds the sheathing assembly. The one or three electrical conductor units include an electrical conductor. In addition, the electrical conductor units include a conductor screening layer. The conductor screening layer surrounds the electrical conductor. The conductor screening layer screens the electrical conductor. Moreover, the electrical conductor units include an insulation layer. The insulation layer surrounds the conductor screening layer. Further, the electrical conductor units include an insulation screening layer. The insulation screening layer surrounds the insulation layer. Also, the electrical conductor units include a metallic screening layer. The metallic screening layer surrounds the semi-conducting water blocking tape layer. The sheathing assembly includes a first layer. The first layer surrounds the core assembly. In addition, the sheathing assembly includes a second layer. The second layer surrounds the first layer. Further, the sheathing assembly includes a third layer. The third layer surrounds the second layer.
BRIEF DESCRIPTION OF FIGURES
[0007] FIG. 1A illustrates a cross sectional view of apower cable assembly, in accordance with an embodiment of the present disclosure; and
[0008] FIG. 1B illustrates a cross sectional view of an electrical conductor unit of the power cable assembly of FIG. 1A, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0009] FIG.1A illustrates a cross sectional view of apower cable assembly cable 100, in accordance with an embodiment of the present disclosure. The power cable assembly 100 is an assembly of a power cable covered with an outer duct/conduit. In addition, the power cable assembly 100 can be utilized supplying power to rural areas, urban areas, sub-urban areas and the like.The power cable assembly 100 can be utilized in power transmission and distribution systems. Moreover, the power cable assembly 100 can be laid underground. The structure of the power cable assembly 100 enables direct installation of the power cable assembly 100. The power cable assembly 100 includes a power cable 102 and a conduit 104. The conduit 104 tightly surrounds the power cable 102. Further, the material of the conduit 102 is chosen in order to enable proper bonding with a material of an outer sheath of the power cable 102. The conduit 104 is a duct layer which provides protection to the power cable 102. In addition, the absence of free space between the power cable 102 and the conduit 104 enables faster detection and restoration of faults in the power cable 102. The faults experienced by the power cable assembly 100 may occur due to open circuit faults, short circuit or cross fault and ground or earth fault.
[0010] The conduit 104 is made of polyethylene. In an embodiment of the present disclosure, the conduit 104 may be made of any other material. The material must bond properly with the material of the outer sheath of the power cable 102. The conduit 104 has a diameter in a range of about 95.4 millimeters – 95.6 millimeters. In an embodiment of the present disclosure, the power cable assembly 100 has a diameter in a range of about 95.4 millimeters – 95.6 millimeters. In an embodiment of the present disclosure, the conduit 104 has a thickness of at least 2.0 millimeters. In another embodiment of the present disclosure, the thickness of the conduit 104 may vary. The material of the conduit 104 is characterized by a plurality of properties. The plurality of properties of the material is essential for the performance of the power cable assembly 100. The plurality of properties include tensile strength, elongation, environmental stress cracking resistance (ESCR), UV resistance, abrasion resistance and temperature range. In addition, the plurality of properties include continuous temperature withstand range, melt flow index (MFI), flammability and rodent and termite behavior. Moreover, the plurality of properties include compatibility with outer sheath of the power cable 102, density, behavior at sub-zero temperature, thermal resistivity, processability and extrudability at desired thickness.
[0011] Further, the plurality of properties include water absorption, reaction to soil alkali and acids, hydraulic stability, color fastness to daylight, color, carbon black content and volume resistivity. The tensile strength of the polymer material corresponds to how much stress the material can endure before failure. In an embodiment of the present disclosure, the material of the conduit 104 has a minimum tensile strength of 12.5 N/mm2 before ageing. Elongation refers to a maximum amount up to which the material can be stretched. In an embodiment of the present disclosure, the material of the conduit 104 has a minimum of 300% elongation at break before ageing. The power cable assembly 100 is treated in air oven at a temperature of 110 degree Celsius with a tolerance of ±2 and for 240 hours. In an embodiment of the present disclosure, the material of the conduit 104 has a minimum of 300% elongation at break after ageing in the air oven. The environmental stress cracking resistance refers to the resistance shown towards brittle failure due to external or internal stresses. The melt flow index of the material is a measure of how many grams of polymer can pass through a standardized capillary under a standard load over 10 minutes. The thermal resistivity is a measure of an ability of the material to resist flow of heat.
[0012] The power cable 102 is an assembly of one or more insulated electrical conductors covered by a sheathing system. The power cable 102 is designed according to voltage requirement, current carrying capacity desired, maximum operating temperature and purpose of application desired by an end customer. The power cable 102 is a three core power cable. The three core power cable corresponds to a power cable with three insulated conductor units inside a core of the power cable 102. In general, the three core cable is used for a perfect balanced 3-phase system. The medium voltage power cable is a cable having an operating voltage in a range of 1 kV and 33 kV. In an embodiment of the present disclosure, the power cable 102 is a 6.35/11kV cable. In an embodiment of the present disclosure, the power cable 102 is a three core insulated XLPE (cross linked polyethylene) cable. In an embodiment of the present disclosure, the power cable 102 has a voltage grade of 11 kV (E). In another embodiment of the present disclosure, the power cable 102 has a voltage grade of 11 kV (UE). In yet another embodiment of the present disclosure, the power cable 102 has a voltage grade of 22 kV (E). In yet another embodiment of the present disclosure, the power cable 102 has a voltage grade of 33 kV (E). Furthermore, the power cable 102 can be any one of simple electrical power cable and hybrid cable. In an embodiment of the present disclosure, the power cable 102 is a simple electrical power cable. In another embodiment of the present disclosure, the power cable 102 is a hybrid cable having one or more optical fiber cable units along with the electrical conductor units.
[0013] The power cable 102 includes a core assembly and a sheathing assembly. The sheathing assembly surrounds the core assembly. The core assembly is an assembly of one or three electrical conductor units. In an embodiment of the present disclosure, the core assembly includes a single electrical conductor unit. In another embodiment of the present disclosure, the core assembly includes three electrical conductor units. In an embodiment of the present disclosure, the core assembly includes odd number of electrical conductor units but not more than three electrical conductor units. In addition, the core assembly includes a filler system. The filler system includes multiple variable sized fillers. The variable sized fillers fill up the empty spaces inside the core assembly. The variable sized fillers maintain the circular geometry of the power cable 102 (explained below in detail in the patent application). The one or three electrical conductor units lie substantially along a longitudinal axis of the power cable assembly 100. Each electrical conductor unit of the one or three conductor units is stranded together. The one or three electrical conductor units include a first electrical conductor unit 106, a second electrical conductor unit 108 and a third electrical conductor unit 110. Each electrical conductor unit of the one or three electrical conductor units has the same structure and dimensions. The one or three electrical conductor units include an electrical conductor. Specifically, the electrical conductor unit 106 includes an electrical conductor 106a (as shown in FIG. 1B). In general, the electrical conductor 106a is used for transmitting and distributing electrical energy along large distances. In an embodiment of the present disclosure, the electrical conductor 106a is a stranded conductor which has several wires twisted together. In another embodiment of the present disclosure, the electrical conductor 106a is a metal portion made of a rod.
[0014] The electrical conductor 106a is made of at least one of aluminium and copper. In an embodiment of the present disclosure, the electrical conductor 106a may be made of any other suitable material ideal for efficient power transmission. In addition, the electrical conductor 106a has a diameter in a range of about 16.2 millimeters - 37.5 millimeters. In an embodiment of the present disclosure, the electrical conductor 106a has a diameter in a range of about 16.2 millimeters - 26.5 millimeters for the three core cable. In another embodiment of the present disclosure, the electrical conductor 106a has a diameter in a range of about 16.2 millimeters - 37.5 millimeters for the single core cable. In an embodiment of the present disclosure, the diameter of the electrical conductor 106a changes as per conductor size and voltage grade. In an embodiment of the present disclosure, the electrical conductor 106a is a water blocked electrical conductor. The three core cable corresponds to a cable with three electrical conductors. In an embodiment of the present disclosure, the three core cable may have an 11 kV (E) voltage grade. In another embodiment of the present disclosure, the three core cable may have an 11 kV (UE) voltage grade. In yet another embodiment of the present disclosure, the three core cable may have a 22 kV (E) voltage grade. In yet another embodiment of the present disclosure, the three core cable may have a 33 kV (E) voltage grade. In an embodiment of the present disclosure, the size of each of the three electrical conductors is 185 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In another embodiment of the present disclosure, the size of each of the three electrical conductors is 240 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of each of the three electrical conductors is 300 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of each of the three electrical conductors is 400 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of each of the three electrical conductors is 500 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E).
[0015] The single core cable corresponds to a cable with one electrical conductor. In an embodiment of the present disclosure, the single core cable may have an 11 kV (E) voltage grade. In another embodiment of the present disclosure, the single core cable may have an 11 kV (UE) voltage grade. In yet another embodiment of the present disclosure, the single core cable may have a 22 kV (E) voltage grade. In yet another embodiment of the present disclosure, the single core cable may have a 33 kV (E) voltage grade. In an embodiment of the present disclosure, the size of the one electrical conductor is 185 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In another embodiment of the present disclosure, the size of the one electrical conductor is 240 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of the one electrical conductor is 300 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of the one electrical conductor is 400 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of the one electrical conductor is 500 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of the one electrical conductor is 630 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of the one electrical conductor is 800 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E). In yet another embodiment of the present disclosure, the size of the one electrical conductor is 1000 square millimeters for cable voltage grade of 11 kV (E), 11 kV (UE), 22 kV (E) and 33 kV (E).
[0016] In an embodiment of the present disclosure, the electrical conductor 106a has a diameter of 16.2 millimeters for 185 sq mm conductor size and each of the four above mentioned voltage grades for three-core cable. Here, E corresponds to Earthed cable. In another embodiment of the present disclosure, the electrical conductor 106a has a diameter of 18.3 millimeters for 240 sq mm conductor size and each of the four above mentioned voltage grades for three-core cable. In yet another embodiment of the present disclosure, the electrical conductor 106a has a diameter of 20.2 millimeters for 300 sq mm conductor size and each of the four above mentioned voltage grades for three-core cable. In yet another embodiment of the present disclosure, the electrical conductor 106a has a diameter of 23.4 millimeters for 400 sq mm conductor size and each of the four above mentioned voltage grades for three-core cable. In yet another embodiment of the present disclosure, the electrical conductor 106a has a diameter of 26.5 millimeters for 500 sq mm conductor size and each of the four above mentioned voltage grades for three-core cable. The electrical conductor unit 106 includes a conductor screening layer 106b. The conductor screening layer 106b surrounds the electrical conductor 106a. The conductor screening layer 106b screens the electrical conductor 106a. The conductor screening layer 106b is formed of semiconducting compound suitable for continuous operating temperature of about 90 degree Celsius. The conductor screening layer 106b has a diameter in a range of about 24.5 millimeters - 24.7 millimeters and a thickness of at least 0.2 millimeter. In an embodiment of the present disclosure, the conductor screening layer 106b has a minimum thickness of 0.2 millimeter and a maximum thickness of 0.5 millimeter. In an embodiment of the present disclosure, the conductor screening layer 106b is made of semi-conductor material.
[0017] In an embodiment of the present disclosure, the conductor screening layer 106b is a layer of semiconducting compound tape. In addition, the conductor screening layer 106b protects the electrical conductor 106a. Moreover, the conductor screening layer 106b maintains a uniform electric field and minimizes electrostatic stresses. The semiconducting compound tape has high electrical conductance, good long term temperature stability, high tensile strength, robust and good penetration resistance. The semiconducting compound used for the conductor screening layer 106b conforms to IS 7098 (Part-2)/IEC 60502-2. The semiconducting compound is extruded over the semiconducting tape and forms the conductor screening layer 106b. Further, the electrical conductor unit 106 includes an insulation layer 106c. The insulation layer 106c surrounds the conductor screening layer 106b. The insulation layer 106c is a protective coating layer over the electrical conductor 106a. The insulation layer 106c is made of cross-linked polyethylene. The cross linked polyethylene is a thermoset resin which has good electrical properties and low dielectric loss factor. The material allows higher operating temperatures for the electrical conductor. In addition, the material enables the power cable assembly 100 to operate continuously at a temperature of about 90 degree Celsius. The insulation layer 106c has a diameter in a range of about 31.9 millimeters – 32.1 millimeters and a thickness in a range of about 3.14 millimeters to 8.8 millimeters. In an embodiment of the present disclosure, the diameter and the thickness of the insulation layer 106c may vary.
[0018] In an embodiment of the present disclosure, the insulation layer 106c has a minimum thickness of 3.14 millimeters for each of the four conductor sizes and 11 kV (E) voltage grade for three-core cable. In an embodiment of the present disclosure, the insulation layer 106c has a maximum thickness of 3.6 millimeters for each of the four conductor sizes and 11 kV (E) voltage grade for three-core cable. In an embodiment of the present disclosure, the insulation layer 106c has a minimum thickness of 7.82 millimeters for each of the four conductor sizes and 33 kV (E) voltage grade for three-core cable. In another embodiment of the present disclosure, the insulation layer 106c has a maximum thickness of 3.6 millimeters for each of the four conductor sizes and 11 kV (E) voltage grade for three-core cable. Furthermore, the electrical conductor unit 106 includes an insulation screening layer 106d. The insulation screening layer 106d surrounds the insulation layer 106c. The insulation screening layer 106d screens or protects the insulation layer 106c and provides extra protection to the electrical conductor 106a. In an embodiment of the present disclosure, the insulation screening layer 106d is made of semi-conductor material. The insulation screening layer 106d is formed of the semiconducting compound suitable for continuous operating temperature of about 90 degree Celsius. In an embodiment of the present disclosure, the insulation screening layer 106d is a layer of semiconducting compound tape. Moreover, the insulation screening layer 106d maintains a uniform electric field and minimizes electrostatic stresses. The semiconducting compound used for the insulation screening layer 106d conforms to IS 7098 (Part-2)/IEC 60502-2. The semiconducting compound is extruded over the XLPE insulation and forms the non-metallic insulation screen. The insulation screening layer 106d has a diameter in a range of about 33.1 millimeters – 33.3 millimeters and a thickness of at least 0.2 millimeter. In an embodiment of the present disclosure, the insulation screening layer 106d has a minimum thickness of 0.2 millimeter and a maximum thickness of 0.5 millimeter. In an embodiment of the present disclosure, the diameter and the thickness of the insulation screening layer 106d may vary.
[0019] In an embodiment of the present disclosure, the electrical conductor unit 106 may include semi-conducting water blocking tape layer 106e. The semi-conducting water blocking tape layer 106e is disposed between the insulation screening layer 106d and a metallic screening layer 106f. The semi-conducting water blocking tape layer 106e prevents ingression of water and moisture inside the electrical conductor unit 106. The semi-conducting water blocking tape layer 106e is applied helically over the insulation screening layer 106d. In an embodiment of the present disclosure, the semi-conducting water blocking tape layer 106e has a thickness in a range of 0.21 millimeter – 0.33 millimeter. In another embodiment of the present disclosure, the thickness of the semi-conducting water blocking tape layer 106e may vary. In another embodiment of the present disclosure, the electrical conductor unit 106 may not include semi-conducting water blocking tape layer 106e.
[0020] The electrical conductor unit 106 includes a metallic screening layer 106f. The metallic screening layer 106f surrounds the semi-conducting water blocking tape layer 106e. The metallic screening layer 106f is made of at least one of copper tape and copper wire. In an embodiment of the present disclosure, the copper tape is an annealed plain copper tape. In another embodiment of the present disclosure, the copper tape is an annealed copper wire. The copper tape is used for shield to keep electromagnetic radiation in and provides a path for fault and leakage currents. The metallic screening layer 106f has a diameter in a range of about 33.9 millimeters – 34.1 millimeters and a thickness of at least 0.045 millimeter. In an embodiment of the present disclosure, the diameter and the thickness of the metallic screening layer 106f may vary.
[0021] The core assembly includes the filler system. The filler system is an arrangement of variable sized fillers inside the core assembly of the power cable assembly 100. The filler system includes variable sized fillers which are positioned in interstices of the core assembly. The interstices are formed after the one or three electrical conductor units are positioned inside the core assembly. The filler system maintains the circular geometry of the power cable assembly 100. In addition, the filler system restricts the movement of the three electrical conductor units 106-110. In an embodiment of the present disclosure, the filler system includes central filler, one or more minor type fillers and one or more major type fillers. The central filler, the one or more minor type fillers and the one or more major type fillers have a circular cross section. In an embodiment of the present disclosure, the power cable assembly 100 includes first filler 112 positioned at a center of the core assembly. The first filler 112 is positioned substantially along the longitudinal axis of the power cable assembly 100. The first filler 112 is the central filler disposed in an interstitial area or empty space between the electrical conductor units 106-110. The first filler 112 fills up the empty space between the electrical conductor units 106-110. The first filler 112 is made of a material selected from a group. The group consists of polypropylene, polyethylene and polyvinyl chloride. The first filler 112 has a diameter in a range of about 4.1 – 7.4 millimeters. In an embodiment of the present disclosure, the diameter of the first filler 112 may vary. In an embodiment of the present disclosure, the power cable assembly 100 includes one or more second fillers 114a-114c positioned inside the core assembly. The one or more second fillers 114a-114c is positioned substantially along the longitudinal axis of the power cable assembly 100. The one or more second fillers 114a-114c is the one or more major type fillers. Each of the one or more second fillers 114a-114c is placed along the periphery of the core assembly. In addition, each of the one or more second fillers 114a-114c is in direct contact with two electrical conductor units of the three electrical conductor units 106-110. Each of the one or more second fillers 114a-114c is made of a material selected from a group. The group consists of polypropylene, polyethylene and polyvinyl chloride. Each of the one or more second fillers 114a-114c fillers has a diameter of about 12.5 – 22.1 millimeters. In an embodiment of the present disclosure, the diameter of the one or more second fillers 114a-114c may vary.
[0022] In an embodiment of the present disclosure, the power cable assembly 100 includes one or more third fillers 116a-116f positioned inside the core assembly. The one or more third fillers 116a-116f is positioned substantially along the longitudinal axis of the power cable assembly 100. The one or more third fillers 116a-116f is the one or more minor type fillers. Each of the one or more third fillers 116a-116f is placed along the periphery of the core assembly. In addition, each filler of the one or more third fillers 116a-116f is in direct contact with one electrical conductor unit of the three electrical conductor units 106-110 and a filler of the one or more second fillers 114a-114c. Each of the one or more third fillers 116a-116f is made of a material selected from a group. The group consists of polypropylene, polyethylene and polyvinyl chloride. Each of the one or more third fillers 116a-116f has a diameter in a range of about 6.2 – 11 millimeters. In an embodiment of the present disclosure, the diameter of the one or more third fillers 116a-116f may vary. In another embodiment of the present disclosure, an optical fiber cable unit (not shown in FIG. 1A) is positioned in one or more interstitial spaces between the one or three electrical conductor units 106-110. The optical fiber cable unit may or may not replace filler selected from a group of the one or more second fillers 114a-114c and the one or more third fillers 116a-116f. The optical fiber cable unit is selected based on the operational requirements. In an example, the optical fiber cable unit may be an armored cable unit or non-armored cable unit. In another example, the optical fiber cable unit may have loose tube fiber configuration or tight buffer tube fiber configuration. In yet another the optical fiber cable unit is a plenum cable unit or a riser cable unit.
[0023] Going further, the power cable assembly 100 includes the sheathing assembly. The sheathing assembly surrounds and protects the core assembly. The sheathing assembly includes a first layer 118. The first layer 118 surrounds the core assembly. The first layer 118 is an inner sheath of the power cable assembly 100. The first layer 118 is made of at least one of polyvinyl chloride and polyethylene. In addition, the first layer 118 is made of an extruded PVC type ST-2 material. In general, polyvinyl chloride is a tough chemically resistant synthetic resin made by polymerizing vinyl chloride. In addition, type ST-2 sheath is a heat resisting sheath intended for use in cables operating at a maximum rated conductor temperature of 90°C. The first layer 118 has a diameter in a range of about 74.1 millimeters – 74.3 millimeters. In an embodiment of the present disclosure, the diameter of the first layer 118 may vary. The first layer 118 has a thickness of at least 0.7 millimeter. In an embodiment of the present disclosure, the thickness of the first layer 118 may vary. Further, the sheathing assembly includes a second layer 120. The second layer 120 surrounds the first layer 118. The second layer 120 is an armoring layer made of galvanized steel wire. The second layer 120 provides mechanical protection to the power cable 102. In addition, galvanized steel wire is used for protection against rust. In general, galvanized steel corresponds to coating of zinc over the steel. In an embodiment of the present disclosure, the galvanized steel wire has a rectangular cross-section. In another embodiment of the present disclosure, the galvanized steel wire has a circular cross-section. The second layer 120 has a diameter in a range of about 82.1 millimeters – 82.3 millimeters. In an embodiment of the present disclosure, the diameter of the second layer 120 may vary. In an embodiment of the present disclosure, the second layer 120 has a nominal thickness of about 4.0 millimeters. In another embodiment of the present disclosure, the nominal thickness of the second layer 120 may vary.
[0024] In an embodiment of the present disclosure, the sheathing assembly may include a binder tape 122. The binder tape 122 may be disposed between the second layer 120 and a third layer 124. The binder tape 122 may be made of at least one of rubberized cotton tape and polyvinyl chloride tape. The cotton tape is used for binding the second layer 120. In an embodiment of the present disclosure, the binder tape 122 may have a diameter which is 0.4 millimeter higher than the diameter of the second layer 120. In an embodiment of the present disclosure, the binder tape 122 may have a thickness of about 0.2 millimeter. In another embodiment of the present disclosure, the sheathing assembly may not include the binder tape 122. The sheathing assembly includes a third layer 124. The third layer 124 surrounds the first layer 120. The third layer 124 is an outer sheath for mechanical, electrical, weather and chemical protection of the power cable 102. The third layer 124 is made of polyethylene. In general, polyethylene is a light, versatile synthetic resin made from polymerization of ethylene. In an embodiment of the present disclosure, the third layer 124 is an extruded PE type ST-7 outer sheath. The third layer 124 has a diameter in a range of about 90.5 millimeters – 90.7 millimeters. In an embodiment of the present disclosure, the diameter of the third layer 124 may vary. The third layer 124 has a thickness of at least 3.0 millimeters. In an embodiment of the present disclosure, the thickness of the third layer 124 may vary. Further, the third layer 124 has increased strength due to the addition of the conduit 104 over the power cable 102. In an embodiment of the present disclosure, the third layer 124 has an increased strength of about 4 to 5 ft-lbs/in at 73 degree Fahrenheit when the power cable assembly 100 is subjected to Izod impact strength test. The material of the third layer 124 is characterized by a plurality of properties desirable in the material. The material of the third layer 124 has a tensile strength without ageing of 12.5 Newton/mm2. The material of the third layer 124 has 300 percent elongation at break without ageing. In addition, the material of the third layer 124 has a carbon black content of 2.5 ± 0.5 percent. The carbon black content is checked for UV protection purpose.
[0025] The present disclosure is described below in greater details with the aid of examples. The following examples of the technical aspect of the present invention will be further explained, but the content of the following is not intended to limit the scope of the present disclosure.
Example 1
[0026] A power cable having a three core unit configuration was prepared. The cross-sectional area of the electrical conductor was at least one of 185 square millimeters, 240 square millimeters, 300 square millimeters, 400 square millimeters and 500 square millimeters. The power cable was configured to operate at a voltage rating of 11 kV (E). The cross-sectional diameter of the electrical conductor was set in a range of approximately 16.2 millimeters to 26.5 millimeters. The nominal thickness of the conductor screening layer was set to be approximately 0.5 millimeters. The nominal thickness of the insulation layer was set to approximately 3.6 millimeters. The nominal thickness of the insulation screening layer was set to be approximately 0.5 millimeters. The cross-sectional diameter of the first filler was set in a range of approximately 4.1 millimeters to 5.8 millimeters. The cross-sectional diameter of each of the one or more second fillers was set in a range of approximately 12.5 millimeters to 17.3 millimeters. Moreover, the cross-sectional diameter of each of the one or more third fillers was set in a range of approximately 6.2 millimeters to 8.6 millimeters. Further, the nominal thickness of the inner sheath was set to be approximately 0.7 millimeters. The power cable may include a binder tape over the armoring layer. The binder tape made be a RC tape or a PVC tape of a nominal thickness of 0.5 millimeter. The thickness of the outer sheath was set to be approximately 3 millimeters. The thickness of the conduit was set to be 2 millimeters. In an embodiment of the present disclosure, the dimensions and material of the conductor screening, the insulation screening and inner sheath is same for single core cable. The diameter of the electrical conductor for the single core cable is in a range of about 16.2 millimeters – 37.5 millimeters. The material of the electrical conductor is same for the single core cable. The single core cable does not include fillers. In addition, the armor layer is non-magnetic for single core cable. The thickness of the outer sheath of the power cable is in a range of 1.84-3.0 millimeters depending on the size of the conductor.
Example 2
[0027] A power cable having a three core unit configuration was prepared. The cross-sectional area of the electrical conductor was at least one of 185 square millimeters, 240 square millimeters, 300 square millimeters, 400 square millimeters and 500 square millimeters. The power cable was configured to operate at a voltage rating of 33 kV (E). The cross-sectional diameter of the electrical conductor was set in a range of approximately 16.2 millimeters to 26.5 millimeters. The nominal thickness of the conductor screening layer was set to be approximately 0.5 millimeters. The nominal thickness of the insulation layer was set to approximately 8.8 millimeters. The nominal thickness of the insulation screening layer was set to be approximately 0.5 millimeters. The cross-sectional diameter of the first filler was set in a range of approximately 5.8 millimeters to 7.4 millimeters based on conductor sizes. The cross-sectional diameter of each of the one or more second fillers was set in a range of approximately 17.5 millimeters to 22.1 millimeters based on conductor sizes. Moreover, the cross-sectional diameter of each of the one or more third fillers was set in a range of approximately 8.8 millimeters to 11 millimeters. Further, the nominal thickness of the inner sheath was set to be approximately 0.7 millimeters. The power cable may include a binder tape over the armoring layer. The binder tape made be a RC tape or a PVC tape of a nominal thickness of 0.4 millimeter. The thickness of the outer sheath was set to be approximately 3 millimeters. The thickness of the conduit was set to be 2 millimeters. In an embodiment of the present disclosure, the dimensions and material of the conductor screening, the insulation screening and inner sheath is same for single core cable. The diameter of the electrical conductor for the single core cable is in a range of about 16.2 millimeters – 37.5 millimeters. The material of the electrical conductor is same for the single core cable. The single core cable does not include fillers. In addition, the armor layer is non-magnetic for single core cable. The thickness of the outer sheath of the power cable is in a range of 1.84-3.0 millimeters depending on the size of the conductor.
Example 3
[0028] A power cable having a three core unit configuration was prepared. The cross-sectional area of the electrical conductor was at least one of 185 square millimeters, 240 square millimeters, 300 square millimeters, 400 square millimeters and 500 square millimeters. The power cable was configured to operate at a voltage rating of 11 kV (UE). The cross-sectional diameter of the electrical conductor was set in a range of approximately 16.2 millimeters to 26.5 millimeters. The nominal thickness of the conductor screening layer was set to be approximately 0.5 millimeters. The nominal thickness of the insulation layer was set to approximately 5.5 millimeters. The nominal thickness of the insulation screening layer was set to be approximately 0.5 millimeters. The cross-sectional diameter of the first filler was set in a range of approximately 4.8 millimeters to 6.5 millimeters based on conductor sizes. The cross-sectional diameter of each of the one or more second fillers was set in a range of approximately 14.5 millimeters to 19.4 millimeters based on conductor sizes. Moreover, the cross-sectional diameter of each of the one or more third fillers was set in a range of approximately 7.2 millimeters to 9.7 millimeters. Further, the nominal thickness of the inner sheath was set to be approximately 0.7 millimeters. The power cable may include a binder tape over the armoring layer. The binder tape made be a RC tape or a PVC tape of a nominal thickness of 0.4 millimeter. The thickness of the outer sheath was set to be approximately 3 millimeters. The thickness of the conduit was set to be 2 millimeters. In an embodiment of the present disclosure, the dimensions and material of the conductor screening, the insulation screening and inner sheath is same for single core cable. The diameter of the electrical conductor for the single core cable is in a range of about 16.2 millimeters – 37.5 millimeters. The material of the electrical conductor is same for the single core cable. The single core cable does not include fillers. In addition, the armor layer is non-magnetic for single core cable. The thickness of the outer sheath of the power cable is in a range of 1.84-3.0 millimeters depending on the size of the conductor.
Example 4
[0029] A power cable having a three core unit configuration was prepared. The cross-sectional area of the electrical conductor was at least one of 185 square millimeters, 240 square millimeters, 300 square millimeters, 400 square millimeters and 500 square millimeters. The power cable was configured to operate at a voltage rating of 22 kV (E). The cross-sectional diameter of the electrical conductor was set in a range of approximately 16.2 millimeters to 26.5 millimeters. The nominal thickness of the conductor screening layer was set to be approximately 0.5 millimeters. The nominal thickness of the insulation layer was set to approximately 6.0 millimeters. The nominal thickness of the insulation screening layer was set to be approximately 0.5 millimeters. The cross-sectional diameter of the first filler was set in a range of approximately 5.0 millimeters to 6.6 millimeters based on conductor sizes. The cross-sectional diameter of each of the one or more second fillers was set in a range of approximately 15.0 millimeters to 19.9 millimeters based on conductor sizes. Moreover, the cross-sectional diameter of each of the one or more third fillers was set in a range of approximately 7.5 millimeters to 10.0 millimeters. Further, the nominal thickness of the inner sheath was set to be approximately 0.7 millimeters. The power cable may include a binder tape over the armoring layer. The binder tape made be a RC tape or a PVC tape of a nominal thickness of 0.4 millimeter. The thickness of the outer sheath was set to be approximately 3 millimeters. The thickness of the conduit was set to be 2 millimeters. In an embodiment of the present disclosure, the dimensions and material of the conductor screening, the insulation screening and inner sheath is same for single core cable. The diameter of the electrical conductor for the single core cable is in a range of about 16.2 millimeters – 37.5 millimeters. The material of the electrical conductor is same for the single core cable. The single core cable does not include fillers. In addition, the armor layer is non-magnetic for single core cable. The thickness of the outer sheath of the power cable is in a range of 1.84-3.0 millimeters depending on the size of the conductor.
[0030] Example 5
[0031] A hybrid power cable having three core unit and one optical fiber cable unit configuration was prepared. The hybrid power cable was configured to operate at a voltage rating of at least one of 11 kilovolts, 22 kilovolts and 33 kilovolts. The cross-sectional area of the electric conductor present in the hybrid power cable was set similar to the power cable of Example 1. Also, the nominal thickness of the conductor screening layer, the insulation layer, the insulation screening layer and the metallic screening layer was set similar as described in Example 1. Further, the filler unit having at most 9 fillers was disposed at the one or more interstitial spaces between the three core units. In addition, an optical fiber cable unit was also disposed at the one or more interstitial spaces between the three electrical conductor units. The cross-sectional diameter of the first filler, the one or more second fillers and the one or more third fillers was set similar to electric power cable configuration as described in Example 1. Further, the nominal thickness of the inner sheath, the armor layer, the rubberized cotton tape and the outer sheath was set similar to power cable configuration as described in Example 1.
[0032] The present disclosure provides numerous advantages over the prior art. The structure of the power cable assembly allows direct laying of the power cable underground. The power cable of the power cable assembly of different cable sizes can be installed underground. The time taken for installation of the power cable is less. In addition, the design of the power cable assembly results in reduction in time taken in detection of faults in the power cable. Moreover, the cost invested in performing the detection of faults in the power cable reduces. Further, the loss in revenue transpired due to fault detection in conventional power cable design is mitigated. Furthermore, the addition of duct over the power cable results in increase in strength of the outer sheath of the power cable. Also, the power cable assembly has increased or comparable ability of withstanding external impacts as opposed to the conventional power cable design.