HIGH AMPACITY POWER CABLE
TECHNICAL FIELD
[0001] The present disclosure relates to the field of electrical power cables. More particularly, the present disclosure relates to a high ampacity power cable 5 for underground applications.
BACKGROUND
[0002] Nowadays, advent of modern devices/machineries results in the growth of global electrical power demands. In order to meet the ever increasing demands, utilities transmit and distribute electrical power at higher and variable 10 loads by means of transmission and distribution (T&D) cables. These cables are characterized as low voltage cables, medium voltage cables and high voltage cables. In general, these cables consist of one or more conductive elements surrounded by semi conductive and insulated polymeric material coatings, a metallic armor and one or more protection layers. However, power transmission 15 and distribution through these cables results in certain distribution losses. Resistive power losses in these cables contribute significantly to the distribution losses.
[0003] Traditionally, several power cable designs are introduced to curb such distribution losses. Most of these power cable designs include usage of circular 20 strands compacted together to form a conductive element having maximum compaction of 92 % to 93 %. This leads to presence of air gaps and limits the amount of metal area that can be put in the same physical area resulting in increase in resistive power losses. Some of these power cable designs incorporate cross-linked polyethylene as polymeric materials in the insulation layer around 25 the conductive element. However, the cross-linked polyethylene insulation layer incorporated provides a continuous operating temperature of 90 degree Celsius thus limiting the current carrying capacity of these cables. Moreover, some of
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these power cable designs introduced a single core cables which involves large installation and laying cost manifold.
[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. 5
OBJECT OF THE DISCLOSURE
[0005] The primary object of the present disclosure is to provide an electric power cable having high current ratings.
[0006] Another object of the present disclosure is to provide a medium voltage power cable having compactly packed non-circular cross-section aluminum 10 strands.
[0007] Yet another object of the present disclosure is to provide an electric power cable having high endurance cross-linked polyethylene insulation enabling a continuous operating temperature of 105 degree Celsius.
[0008] Yet another object of the present disclosure is to provide an electric 15 power cable having enhanced electrical conductivity, and reduced transmission and distribution losses.
[0009] Yet another object of the present disclosure is to provide an electric power cable to cater a peak demand without altering the cable size thus saving operational costs and capital costs. 20
SUMMARY
[0010] In an aspect, the present disclosure provides an electric power cable. The electric power cable includes one or three core units. The one or three core units are stranded together substantially around a longitudinal axis of the electric power cable. Each core unit includes an electric conductor for conducting electricity. 25 The electric conductor is surrounded by a conductor screening layer. In addition, each core unit includes an insulation layer surrounding the conductor screening layer. The insulation layer is made of cross-linked polyethylene. Moreover, the
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insulation layer enables the electric power cable to operate continuously at a temperature of 105 degree Celsius. Further, each core unit includes an insulation screening layer over the insulation layer and a metallic screening layer over the insulation screening layer. Further, the electric power cable includes a sheathing unit surrounding the one or three core units. The sheathing unit includes a first 5 layer surrounding the one or three core units. In addition, the sheathing unit includes a second layer surrounding the first layer and a third layer surrounding the second layer. Further, the electric conductor is made of at least one layer of a plurality of non-circular cross-section aluminum strands surrounded by a layer of water swellable material. The conductor screening layer and the insulation 10 screening layer are formed of extruded semiconducting compound suitable for a continuous operating temperature of 105 degree Celsius. The metallic screening layer is made of at least one of an annealed plain copper tape and an annealed plain copper wire. The first layer is made of at least one material selected from a group consisting of polyvinyl chloride and polyethylene. The second layer is an 15 armoring layer made of a plurality of galvanized steel wires. The third layer is made of at least one material selected from a group consisting of polyvinyl chloride and polyethylene. Furthermore, the electrical conductor has a diameter in a range of about 16.3 millimeters to 37.7 millimeters. The conductor screening layer has a thickness of at least 0.2 millimeters. The insulation layer has a 20 thickness in a range of about 3.14 millimeters to 8.8 millimeters. The insulation screening layer has a thickness of at least 0.2 millimeters. The metallic screening layer has a thickness of at least 0.045 millimeters. The first layer has a thickness of at least 0.7 millimeters. The third layer has a thickness in a range of about 1.84 millimeters to 3.0 millimeters. Moreover, the electric power cable has a current 25 carrying capacity in a range of about 318 amperes to 538 amperes.
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BRIEF DESCRIPTION OF FIGURES
[0011] FIG. 1A illustrates a cross sectional view of an electric power cable, in accordance with an embodiment of the present disclosure; and
[0012] FIG. 1B illustrates a cross sectional view of an electrical conductor of the electric power cable of FIG. 1A, in accordance with an embodiment of the 5 present disclosure;
DETAILED DESCRIPTION
[0013] FIG. 1A illustrates a cross-sectional view of an electric power cable 100, in accordance with an embodiment of the present disclosure. The electric power cable 100 can be utilized in power transmission and distribution systems. In 10 addition, the electric power cable 100 can be utilized for supplying power to rural areas, urban areas, sub-urban areas and the like. Further, the electric power cable 100 is stringed overhead across the transmission towers for transmitting and distributing electrical energy. In addition, the electric power cable 100 can be laid underground for transmitting and distributing electrical energy. 15
[0014] The electric power cable 100 consists of at least one core units covered by a sheathing unit. The electric power cable 100 is configured to maximize a current carrying capacity. In general, the current carrying capacity is defined as the maximum amount of electric current the electric power cable carries before sustaining immediate or progressive deterioration. The electric power cable 100 20 has a current carrying capacity in a range of about 318 amperes to 538 amperes. In general, the electric power cable can be at least one of a single core power cable and multicore power cable. In an embodiment of the present disclosure, the electric power cable 100 is a three core power cable. In another embodiment of the present disclosure, the electric power cable 100 is a single core power cable. 25 The three core power cable corresponds to a power cable with three core units. In general, the three core power cable is used for a perfect balanced 3-phase system.
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[0015] In an embodiment of the present disclosure, the three core power cable may have an 11 kV (E) voltage grade. The terminology “E” introduced here, generally represents the earthed cables known to a person skilled in the art. In another embodiment of the present disclosure, the three core power cable may have an 11 kV (UE) voltage grade. The terminology “UE” introduced here, is 5 generally representing the unearthed cables known to a person skilled in the art. In yet another embodiment of the present disclosure, the three core power cable may have a 22 kV (E) voltage grade. In yet another embodiment of the present disclosure, the three core power cable may have a 33 kV (E) voltage grade. In an embodiment of the present disclosure, the size of each of the three electrical 10 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 15 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 20 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).
[0016] In an embodiment of the present disclosure, the single core power cable may have an 11 kV (E) voltage grade. In another embodiment of the present disclosure, the single core power cable may have an 11 kV (UE) voltage grade. 25 In yet another embodiment of the present disclosure, the single core power cable may have a 22 kV (E) voltage grade. In yet another embodiment of the present disclosure, the single core power cable may have a 33 kV (E) voltage grade. In
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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 5 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 10 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).
[0017] 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 15 (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 20 (E), 11 kV (UE), 22 kV (E) and 33 kV (E).
[0018] Further, the electric power cable 100 is a medium voltage cable. In an embodiment of the present disclosure, the electric power cable 100 has a voltage rating in a range of about 11 kilovolts to 33 kilovolts. Furthermore, the electrical power cable 100 can be any one of simple electrical cable and hybrid cable. In an 25 embodiment of the present disclosure, the electric power cable 100 is a simple electrical cable. In another embodiment of the present disclosure, the electric
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power cable 100 is a hybrid cable having one or more optical fiber cable units along with the electrical conductor units.
[0019] Referring to FIG. 1A, the electric power cable 100 includes one or three core units and a sheathing unit. In an embodiment of the present disclosure, the sheathing unit surrounds the one or three core units. In addition, the electric 5 power cable 100 includes a filler unit. The filler unit includes multiple variable sized fillers. The variable sized fillers fill up the empty spaces between the three core units. Moreover, the variable sized fillers maintain the circular geometry of the electric power cable 100 (explained below in detail in the patent application).
[0020] The one or three core units associated with the electric power cable 100 10 includes a first core unit 102, a second core unit 104, and a third core unit 106. The first core unit 102, the second core unit 104, and the third core unit 106 are stranded together substantially around a longitudinal axis (not shown) of the electric power cable100. The skilled artisan will appreciate that the longitudinal axis is not a physical feature; rather, it is a reference line passing through a 15 geometrical center (not shown) of the electric power cable100.
[0021] Going further, each core unit is an assembly of an electric conductor surrounded by one or more protection layers. Each core unit of the one or three core units has the same structure and dimensions. Referring to FIG. 1B, the first core unit 102 includes an electric conductor 102a for conducting electric current 20 in the electric power cable 100. The electric conductor 102a includes a central conductor 102b surrounded by at least one layer of a plurality of non-circular cross-section aluminum strands. In an embodiment of the present disclosure, the central conductor 102b is a circular cross-section strands. Moreover, the central conductor 102b is surrounded by a first plurality of non-circular aluminum 25 strands 102c. The first plurality of non-circular aluminum strands 102c is compactly packed with each other to form a layer around the central conductor 102b. In an embodiment of the present disclosure, a plurality of trapezoidal
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cross-section aluminum strands is helically and compactly packed around the central conductor 102b. The first plurality of non-circular aluminum strands 102c are symmetrically laid around the central conductor 102b.
[0022] The first plurality of non-circular aluminum strands 102c is further surrounded by a second plurality of non-circular aluminum strands 102d. The 5 second plurality of non-circular aluminum strands 102d is compactly packed around the first plurality of non-circular aluminum strands 102c. In an embodiment of the present disclosure, the plurality of trapezoidal cross-section aluminum strands is helically and compactly packed to form a layer of aluminum strands. The second plurality of non-circular aluminum strands 102d is 10 symmetrically laid around the first plurality of non-circular aluminum strands 102c. The first plurality of non-circular aluminum strands 102c and the second plurality of non-circular aluminum strands 102d are compactly laid such that there is substantially little or no voids left in between the adjacent strands.
[0023] The central conductor 102b, the first plurality of non-circular aluminum 15 strands 102c and the second plurality of non-circular aluminum strands 102d together form the electric conductor 102a of the electric power cable 100. The central conductor 102b, the first plurality of non-circular aluminum strands 102c and the second plurality of non-circular aluminum strands 102d are formed by utilizing one or more heat treatment processes. In an embodiment of the present 20 disclosure, the aluminum strands are annealed at a pre-defined temperature to achieve the conductivity of more than 60 % IACS.
[0024] The electric conductor 102a has a diameter in a range of 16.3 millimeters to 37.7 millimeters. In embodiment of the present disclosure, the electric conductor 102a associated with a three core power cable has a diameter in a range 25 of about 16.3 millimeters to 26.7 millimeters. In another embodiment of the present disclosure, the electric conductor 102a associated with a single core power cable has a diameter in a range of about 16.3 millimeters to 37.7
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millimeters. In an embodiment of the present disclosure, the electric conductor 102a has a cross-sectional area of about 185 square millimeters. In another embodiment of the present disclosure, the electric conductor 102a has a cross-sectional area of about 240 square millimeters. In yet another embodiment of the present disclosure, the electric conductor 102a has a cross-sectional area of about 5 300 square millimeters. In yet another embodiment of the present disclosure, the electric conductor has a cross-sectional area of about 400 square millimeters. In yet another embodiment of the present disclosure, the electric conductor has a cross-sectional area of about 500 square millimeters.
[0025] The electric conductor 102a is further surrounded by the one or more 10 protection layers. The one or more protection layers are utilized for providing features such as cable insulation, safety, strength and armoring. The electric conductor 102a is surrounded by a layer of water swellable material 102e (as shown in FIG. 1B). The layer of water swellable material 102e forms a barrier to prevent the ingress of moisture inside the electric conductor 102a. Further, the 15 electric conductor 102a is surrounded by a conductor screening layer 102f. The conductor screening layer 102f surrounds the electric conductor such that there is substantially little or no voids left in between the electric conductor 102a and the conductor screening layer 102f. The conductor screening layer 102f is formed of extruded semiconducting compound suitable for continuous operating 20 temperature of about 105 degree Celsius. In general, continuous operating temperature is defined as a temperature that the electric power cable can withstand during its lifetime. Generally, the continuous operating temperature of the electric power cable is limited by thermal aging characteristics of the polymeric materials utilized for insulation. 25
[0026] The conductor screening layer 102f has a thickness of at least 0.2 millimeters. In an embodiment of the present disclosure, the conductor screening layer 102f is a layer of semiconducting compound tape. In addition, the
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conductor screening layer 102f protects the electric conductor 102a. Moreover, the conductor screening layer 102f 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 5 the conductor screening layer 102f conforms to IS 7098 (Part-2)/IEC 60502-2. The semiconducting compound is extruded over the semiconducting tape and forms the conductor screening layer 102f.
[0027] Further, the first core unit 102 includes an insulation layer 102g. The insulation layer 102g surrounds the conductor screening layer 102f. The 10 insulation layer 102g provides insulation to the electric conductor 102a, and prevents leakage of current and protects humans from shock. The insulation layer 102g is a protective coating layer over the electric conductor 102a. The insulation layer 102g is made of cross-linked polyethylene. The cross linked polyethylene is a thermoset resin which has good electrical properties and low 15 dielectric loss factor. In addition, cross linked polyethylene or XLPE is a form of polyethylene with cross-link bonds. The cross linking effect inhibits movement of molecules with respect to each other under the simulation of heat and gives improved stability at elevated temperatures. The material allows higher operating temperatures for the electrical conductor. In an embodiment of the present 20 disclosure, the insulation layer 102g enables the electric power cable 100 to operate continuously at a temperature of 105 degree Celsius. The insulation layer 102g has a thickness in a range of about 3.14 millimeters to 8.8 millimeters.
[0028] Furthermore, the first core unit 102 includes an insulation screening layer 102h. The insulation screening layer 102h surrounds the insulation layer102g. 25 The insulation screening layer 102h screens or protects the insulation layer 102g and provides extra protection to the electric conductor 102a. In an embodiment of the present disclosure, the insulation screening layer 102h is made of an
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extruded semi-conductor material suitable for the continuous operating temperature of about 105 degree Celsius. In an embodiment of the present disclosure, the insulation screening layer 102h is a layer of semiconducting compound tape. Moreover, the insulation screening layer 102h maintains a uniform electric field and minimizes electrostatic stresses. The semiconducting 5 compound tape has high electrical conductance, good long term temperature stability, high tensile strength, robust and good penetration resistance. The insulation screening layer 102h has a thickness of at least 0.2 millimeter. The semiconducting compound used for the insulation screening layer 102h conforms to IS 7098 (Part-2)/IEC 60502-2. The semiconducting compound is extruded 10 over the XLPE insulation and forms the non-metallic insulation screen.
[0029] In an embodiment of the present disclosure, the first core unit 102 includes a semiconducting water swellable tape 102i. The semiconducting water swellable tape 102i surrounds the insulation screening layer 102h. The semiconducting water swellable tape 102i prevents ingression of water and 15 moisture inside the electric conductor102a. In an example, 11x3x300 sq. mm power cable includes a semiconducting water swellable tape of thickness 0.3 millimeters. The semiconducting water swellable tape associated with the 11x3x300 sq. mm power cable has a weight of about 118 grams per square meter. In addition, the semiconducting water swellable tape associated with the 20 11x3x300 sq. mm power cable swells at least to a height of about 12 millimeters per minute.
[0030] Going further, the first core unit 102 includes a metallic screening layer 102j. The metallic screening layer 102j surrounds the insulation screening layer 102h. In an embodiment of the present disclosure, the semiconducting water 25 swellable tape 102i is disposed between the insulation screening layer 102h and the metallic screening layer 102j. Further, the metallic screening layer 102j is made of at least one of annealed plain copper tape and annealed plain copper
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wire. In an embodiment of the present disclosure, the metallic screening layer 102j is an annealed plain copper tape. Moreover, the metallic screening layer 102j is used as shield to keep electromagnetic radiation in and provides a path for fault and leakage currents. In addition, the metallic screening layer 102j has a thickness of at least 0.045 millimeters. In an example, a 11x3x300 sq. mm power 5 cable includes an annealed plain copper tape of thickness in a range of about 0.055 millimeters to 0.065 millimeters. The annealed plain copper tape associated with the 11x3x300 sq. mm power cable has a width of about 40 millimeters.
[0031] Continuing with FIG. 1A, the electric power cable 100 includes the 10 sheathing unit. In an embodiment of the present disclosure, the sheathing unit surrounds and protects the one or three core units. The sheathing unit includes a first layer 114. The first layer 114 surrounds the one or three core units. The first layer 114 is an inner sheath of the electric power cable 100. The first layer 114 is made of at least one material selected from a group consisting of polyvinyl 15 chloride and polyethylene. In an embodiment of the present disclosure, the first layer 114 is made of polyvinyl chloride. In addition, the first layer 114 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 20 operating at a maximum rated conductor temperature of 95°C. The first layer 114 has a thickness of at least 0.7 millimeters.
[0032] Further, the sheathing unit includes a second layer 116. The second layer 116 surrounds the first layer 114. The second layer 116 is an armoring layer made of a plurality of galvanized steel wires stranded together. In general, 25 galvanized steel corresponds to coating of zinc over the steel. The second layer 116 provides mechanical strength to the electric power cable 100. In addition, each of the plurality of galvanized steel wires is used for protection against rust.
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In an embodiment of the present disclosure, each galvanized steel wire has a rectangular cross-section. In another embodiment of the present disclosure, each galvanized steel wire has a circular cross-section.
[0033] In an example, 11x3x300 sq. mm power cable has an armor layer made of galvanized wires of rectangular cross-section. Each galvanized wire associated 5 with the 11x3x300 sq. mm power cable has a pre-defined thickness of about 4.0 millimeters and a pre-defined width of about 0.8 millimeters. The armor layer associated with the 11x3x300 sq. mm power cable has a pre-defined equivalent area of about 147.2 square millimeters. In addition, the armor layer associated with the 11x3x300 sq. mm power cable has a pre-defined short-circuit current 10 carrying capacity of about 6.84 kilo-amperes per second.
[0034] Further, the sheathing unit includes a third layer 120. The third layer 120 surrounds the second layer 116. The third layer 120 is an outer sheath for mechanical, electrical, weather and chemical protection of the electric power cable 100. The third layer 120 is made of a material suitable for the continuous 15 operating temperature of about 95 degree Celsius. The third layer 120 is made of at least one material selected from a group consisting of polyvinyl chloride and polyethylene. In an embodiment of the present disclosure, the third layer 120 is made of polyvinyl chloride. In general, polyvinyl chloride is a light, versatile synthetic resin made from polymerization of vinyl chloride. In an embodiment of 20 the present disclosure, the third layer 120 is an extruded PVC type ST-2 outer sheath. The third layer 120 has a thickness in a range of about 1.84 millimeters to 3.0 millimeters.
[0035] In an embodiment of the present disclosure, electric power cable 100 includes one or more binder tapes 118. The one or more binder tapes 118 are 25 disposed between the second layer 116 and the third layer 120. The one or more binder tapes 118 are used for binding the second layer 116. The one or more binder tapes 118 are selected from a group consisting of rubberized cotton tape
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and polyvinyl chloride tape. In an embodiment of the present disclosure, the one or more binder tapes 118 includes a first rubberized cotton tape 118a and a second rubberized cotton tape 118b. In general, the rubberized cotton tapes are cotton clothes impregnated with tacky rubber compounds. Each rubberized cotton tape of the one or more binder tapes 118 has a thickness in a range of about 5 0.2 millimeters to 0.4 millimeters. In an embodiment of the present disclosure, the thickness of each of the rubberized cotton tape is about 0.2 millimeters. In another embodiment of the present disclosure, the thickness of each rubberized cotton tape is about 0.3 millimeters. In yet another embodiment of the present disclosure, the thickness of each rubberized cotton tape is about 0.4 millimeters. 10
[0036] Referring to FIG. 1A, the electric power cable 100 includes the filler unit. The filler unit is present in the three core power cable. Further, the filler unit is an arrangement of variable sized fillers between the three core units of the electric power cable 100. The filler unit includes variable sized fillers which are positioned in one or more interstices between the three core units. The filler unit 15 maintains the circular geometry of the electric power cable 100. In addition, the filler unit restricts the movement of the three core units 102-106. In an embodiment of the present disclosure, the filler unit includes central filler, one or more minor type fillers and one or more major type fillers. Moreover, the filler unit is absent in the single core power cable. 20
[0037] 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 electric power cable 100 includes a first filler 108 positioned at a geometrical center of the electric power cable 100. The first filler 108 is extended substantially along the longitudinal axis of the electric power cable100. The first 25 filler 108 is the central filler disposed in an interstitial area or empty space between the three core units 102-106. The first filler 108 fills up the empty space between the three core units 102-106. The first filler 108 is in direct contact with
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each of the three core units 102-106. The first filler 108 is made of polyvinyl chloride. In an embodiment of the present disclosure, the first filler 108 has a cross-sectional diameter in a range of about 4.1 millimeters to 7.4 millimeters. In an embodiment of the present disclosure, the first filler 108 is made of at least one material selected from a group consisting of polyvinyl chloride, polypropylene 5 and polyethylene.
[0038] In an embodiment of the present disclosure, the electric power cable 100 includes one or more second fillers 110a-110c positioned in one or more interstitial spaces between the one or three core units and the first layer 114. The one or more second fillers are extended substantially along the longitudinal axis 10 of the electric power cable 100. In an embodiment of the present disclosure, the one or more second fillers 110a-110c are one or more major type fillers. Each of the one or more second fillers is in direct contact with two core units of the three core units 102-106. In an embodiment of the present disclosure, each of the one or more second fillers is made of at least one material selected from a group 15 consisting of polyvinyl chloride, polypropylene and polyethylene. In an embodiment of the present disclosure, each of the one or more second fillers has a cross-sectional diameter in a range of about 12.5 millimeters to 22.1 millimeters.
[0039] In an embodiment of the present disclosure, the electric power cable 100 includes one or more third fillers 112a-112f positioned in one or more interstitial 20 spaces between the one or three core units and the first layer 114. The one or more third fillers are extended substantially along the longitudinal axis of the electric power cable 100. In an embodiment of the present disclosure, the one or more third fillers 110a-110c are one or more minor type fillers. Each of the one or more third fillers is in direct contact with a core unit of the three core units and 25 the one or more second fillers 110a-110c. In an embodiment of the present disclosure, each of the one or more third fillers is made of at least one material selected from a group consisting of polyvinyl chloride, polypropylene and
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polyethylene. In an embodiment of the present disclosure, each of the one or more second fillers has a cross-sectional diameter in a range of about 6.2 millimeters to 11.0 millimeters.
[0040] 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 5 between the one or three core units and the first layer 114. The optical fiber cable unit may or may not replace filler selected from a group of the first filler 108, the one or more second fillers 110a-110c and the one or more third fillers 112a-112f. 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-10 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.
[0041] The present invention is described below in greater details with the aid of examples. The following examples of the technical aspect of the present 15 invention will be further explained, but the content of the following is not intended to limit the scope of the present invention.
[0042] Example 1
[0043] An electric power cable having a three core unit configuration was prepared in which the cross-sectional area of the electric conductor was set in a 20 range of approximately 185 square millimeters to 500 square millimeters. Moreover, the electric power cable is an earthed power cable. The electric power cable was configured to operate at a voltage rating of 11 kV. The cross-sectional diameter of the electric conductor was set in a range of approximately 16.3 millimeters to 26.7 millimeters. The nominal thickness of the conductor 25 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
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0.5 millimeters. The nominal thickness of the metallic screening layer was set in a range of about 0.055 millimeters to 0.065 millimeters. Further, the filler unit having 10 fillers was disposed at the one or more interstitial spaces between the three core units. 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 5 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 armor layer was made of approximately 10 45 galvanized steel wires of rectangular cross-section. The thickness and width of each of the galvanized steel wire was set to be approximately 4 millimeters and 0.8 millimeters respectively. The thickness of the each of the rubberized cotton tape was set to be in a range of approximately 0.2 millimeters to 0.4 millimeters. The thickness of the outer sheath was set to be approximately 3 millimeters. 15 Further, maximum direct current resistance of the electric power cable was observed to be in a range of about 0.05445 – 0.1476 ohm per kilometer at 20 degree Celsius. Rated current of the electric power cable in ground was observed to be in a range of about 322 – 538 amperes. In addition, resistive power loss of the electric power cable operating at full rated current was observed to be in a 20 range of about 514990 – 561366 kilowatt-hour per kilometer per year.
[0044] Example 2
[0045] An electric power cable having a three core unit configuration was prepared in which the cross-sectional area of the electric conductor was set in a range of approximately 185 square millimeters to 500 square millimeters. 25 Moreover, the electric power cable is an unearthed power cable. The electric power cable was configured to operate at a voltage rating of 11 kV. The cross-sectional diameter of the electric conductor was set in a range of approximately
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16.3 millimeters to 26.7 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 nominal thickness of the metallic screening layer was set in 5 a range of about 0.055 millimeters to 0.065 millimeters. Further, the filler unit having 10 fillers was disposed at the one or more interstitial spaces between the three core units. The cross-sectional diameter of the first filler was set in a range of approximately 4.8 millimeters to 6.5 millimeters. The cross-sectional diameter of each of the one or more second fillers was set in a range of approximately 14.5 10 millimeters to 19.5 millimeters. Moreover, the cross-sectional diameter of each of the one or more third fillers was set in a range of approximately 7.3 millimeters to 9.8 millimeters. Further, the nominal thickness of the inner sheath was set to be approximately 0.7 millimeters. The armor layer was made of approximately 45 galvanized steel wires of rectangular cross-section. The thickness and width of 15 each of the galvanized steel wire was set to be approximately 4 millimeters and 0.8 millimeters respectively. The thickness of the each of the rubberized cotton tape was set to be in a range of approximately 0.2 millimeters to 0.4 millimeters. The thickness of the outer sheath was set to be approximately 3 millimeters. The plurality of electrical parameters was observed similar to 11 kV(E) electric power 20 cable of Example 1.
[0046] Example 3
[0047] An electric power cable having a three core unit configuration was prepared in which the cross-sectional area of the electric conductor was set in a range of approximately 185 square millimeters to 500 square millimeters. 25 Moreover, the electric power cable is an earthed power cable. The electric power cable was configured to operate at a voltage rating of 22 kV. The cross-sectional diameter of the electric conductor was set in a range of approximately 16.3
20
millimeters to 26.7 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 nominal thickness of the metallic screening layer was set in 5 a range of about 0.055 millimeters to 0.065 millimeters. Further, the filler unit having 10 fillers was disposed at the one or more interstitial spaces between the three core units. The cross-sectional diameter of the first filler was set in a range of approximately 5.0 millimeters to 6.7 millimeters. The cross-sectional diameter of each of the one or more second fillers was set in a range of approximately 15.0 10 millimeters to 20.0 millimeters. 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 armor layer was made of approximately 45 galvanized steel wires of rectangular cross-section. The thickness and width of 15 each of the galvanized steel wire was set to be approximately 4 millimeters and 0.8 millimeters respectively. The thickness of the each of the rubberized cotton tape was set to be in a range of approximately 0.2 millimeters to 0.4 millimeters. The thickness of the outer sheath was set to be approximately 3 millimeters. Further, maximum direct current resistance of the electric power cable was 20 observed to be in a range of about 0.05445 – 0.1476 ohm per kilometer at 20 degree Celsius. Rated current of the electric power cable in ground was observed to be in a range of about 318 – 534 amperes. In addition, resistive power loss of the electric power cable operating at full rated current was observed to be in a range of about 502275 – 553050 kilowatt-hour per kilometer per year. 25
[0048] Example 4
[0049] An electric power cable having a three core unit configuration was prepared in which the cross-sectional area of the electric conductor was set in a
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range of approximately 185 square millimeters to 500 square millimeters. Moreover, the electric power cable is an earthed power cable. The electric power cable was configured to operate at a voltage rating of 33 kilovolts. The cross-sectional diameter of the electric conductor was set in a range of approximately 16.3 millimeters to 26.7 millimeters. The nominal thickness of the conductor 5 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 nominal thickness of the metallic screening layer was set in a range of about 0.055 millimeters to 0.065 millimeters. Further, the filler unit 10 having 10 fillers was disposed at the one or more interstitial spaces between the three core units. The cross-sectional diameter of the first filler was set in a range of approximately 5.8 millimeters to 7.4 millimeters. 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. Moreover, the cross-sectional diameter of each 15 of the one or more third fillers was set in a range of approximately 8.8 millimeters to 11.0 millimeters. Further, the nominal thickness of the inner sheath was set to be approximately 0.7 millimeters. The armor layer was made of approximately 45 galvanized steel wires of rectangular cross-section. The thickness and width of each of the galvanized steel wire was set to be approximately 4 millimeters and 20 0.8 millimeters respectively. The thickness of the each of the rubberized cotton tape was set to be in a range of approximately 0.2 millimeters to 0.4 millimeters. The thickness of the outer sheath was set to be approximately 3 millimeters. The plurality of electrical parameters was observed similar to 22 kV(E) electric power cable of Example 3. 25
[0050] Example 5
[0051] An electric power cable having a single core unit configuration was prepared in which the cross-sectional area of the electric conductor was set in a
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range of approximately 185 square millimeters to 1000 square millimeters. The electric power cable was configured to operate at a voltage rating of 11 kilovolts. The cross-sectional diameter of the electric conductor was set in a range of approximately 16.3 millimeters to 37.7 millimeters. The nominal thickness of the conductor screening layer was set to be approximately 0.5 millimeters. The 5 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 nominal thickness of the metallic screening layer was set in a range of about 0.055 millimeters to 0.065 millimeters. The filler unit was omitted from the electric power cable. Further, the nominal 10 thickness of the inner sheath was set to be approximately 0.7 millimeters. The armor layer was made of approximately 45 galvanized steel wires of rectangular cross-section. The thickness and width of each of the galvanized steel wire was set to be approximately 4 millimeters and 0.8 millimeters respectively. The thickness of the each of the rubberized cotton tape was set to be in a range of 15 approximately 0.2 millimeters to 0.4 millimeters. The thickness of the outer sheath was set in a range of about 1.84 millimeters to 3 millimeters.
[0052] Example 6
[0053] An electric power cable having a single core unit configuration was prepared in which the cross-sectional area of the electric conductor was set in a 20 range of approximately 185 square millimeters to 1000 square millimeters. The electric power cable was configured to operate at a voltage rating of 33 kilovolts. The cross-sectional diameter of the electric conductor was set in a range of approximately 16.3 millimeters to 37.7 millimeters. The nominal thickness of the conductor screening layer was set to be approximately 0.5 millimeters. The 25 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 nominal thickness of the metallic screening
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layer was set in a range of about 0.055 millimeters to 0.065 millimeters. The filler unit was omitted from the electric power cable. Further, the nominal thickness of the inner sheath was set to be approximately 0.7 millimeters. The armor layer was made of approximately 45 galvanized steel wires of rectangular cross-section. The thickness and width of each of the galvanized steel wire was 5 set to be approximately 4 millimeters and 0.8 millimeters respectively. The thickness of the each of the rubberized cotton tape was set to be in a range of approximately 0.2 millimeters to 0.4 millimeters. The thickness of the outer sheath was set in a range of about 1.84 millimeters to 3 millimeters.
[0054] Example 7 10
[0055] 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 about 11 kilovolts to 33 kilovolts. The cross-sectional area of the electric conductor present in the hybrid power cable was set similar to the electric power cable of Example 1. Also, the nominal thickness of 15 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 core 20 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 electric power cable configuration as described in Example 1. 25 Moreover, electrical parameters of the hybrid power cable was observed similar to the electrical parameters of the electric power cables as discussed in Example 1 to Example 4.
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[0056] The present disclosure provides numerous advantages over the prior art. The present disclosure provides the electric power cable having high current ratings. The present disclosure provides a medium voltage power cable having compactly packed non-circular cross-section aluminum strands. The electric power cable have high endurance cross-linked polyethylene insulation enabling a 5 continuous operating temperature of 105 degree Celsius. The electric power cable have enhanced electrical conductivity, and reduced transmission and distribution losses. The electric power cable caters the peak demand without altering the cable size thus saving operational costs and capital costs.

Claims
We Claim:
1. An electric power cable, comprising:
one or three core units stranded together substantially around a longitudinal axis of the electric power cable, wherein each core unit comprises: 5
an electric conductor for conducting electricity, wherein the electric conductor is made of at least one layer of a plurality of non-circular cross-section aluminum strands surrounded by a layer of water swellable material and wherein the electrical conductor has a diameter in a range of about 16.3 millimeters to 37.7 millimeters; 10
a conductor screening layer surrounding the electrical conductor, wherein the conductor screening layer is formed of extruded semiconducting compound suitable for continuous operating temperature of 105 degree Celsius and wherein the conductor screening layer has a thickness of at least 0.2 millimeters; 15
an insulation layer surrounding the conductor screening layer, wherein the insulation layer is made of cross-linked polyethylene enabling the electric power cable to operate continuously at a temperature of 105 degree Celsius and wherein the insulation layer has a thickness in a range of about 3.14 millimeters to 8.8 millimeters; 20
an insulation screening layer surrounding the insulation layer, wherein the insulation screening layer is formed of extruded semiconducting compound suitable for continuous operating temperature of 105 degree Celsius and wherein the insulation screening layer has a thickness of at least 0.2 millimeters; 25
a metallic screening layer surrounding the insulation screening layer, wherein the metallic screening layer is made of at least one of annealed plain copper tape and annealed plain copper wire and wherein the metallic screening layer has a thickness of at least 0.045 millimeters; and
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a sheathing unit surrounding the one or three core units, wherein the sheathing unit comprises:
a first layer, wherein the first layer has a thickness of at least 0.7 millimeters and wherein the first layer is made of at least one material selected 5 from a group consisting of polyvinyl chloride and polyethylene;
a second layer surrounding the first layer, wherein the second layer is an armoring layer made of a plurality of galvanized steel wires;
a third layer surrounding the second layer, wherein the third layer has a thickness in a range of about 1.84 millimeters to 3.0 millimeters, wherein the third 10 layer is made of at least one material selected from a group consisting of polyvinyl chloride and polyethylene and wherein the electric power cable has a current carrying capacity in a range of about 318 amperes to 538 amperes.
2. The electric power cable as recited in claim 1, wherein the electric power cable has a pre-defined voltage rating in a range of about 11 kilovolts to 33 kilovolts. 15
3. The electric power cable as recited in claim 1, further comprising a semiconducting water swellable tape disposed between the insulation screening layer and the metallic screening layer.
4. The electric power cable as recited in claim 1, further comprising one or more binder tapes disposed between the second layer and the third layer, wherein the 20 one or more binder tapes are selected from a group consisting of rubberized cotton tape and polyvinyl chloride tape.
5. The electric power cable as recited in claim 1, wherein each galvanized steel wire of the plurality of galvanized steel wires has a rectangular cross-section.
6. The electric power cable as recited in claim 1, wherein each galvanized steel wire 25 has a circular cross-section.
7. The electric power cable as recited in claim 1, further comprising first filler positioned at a geometrical center of the electric power cable and extended substantially along the longitudinal axis of the electric power cable, wherein the
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first filler has a cross-sectional diameter in a range of about 4.1 millimeters to 7.4 millimeters and wherein the first filler is made of at least one material selected from a group consisting of polyvinyl chloride, polypropylene and polyethylene.
8. The electric power cable as recited in claim 1, further comprising one or more second fillers positioned in one or more interstitial spaces between the one or 5 three core units and the first layer of the sheathing unit, wherein the one or more second fillers are extended substantially along the longitudinal axis of the electric power cable, wherein each of the one or more second fillers has a diameter in a range of about 12.5 millimeters to 22.1 millimeters and wherein each of the one or more second fillers is made of at least one material selected from a group 10 consisting of polyvinyl chloride, polypropylene and polyethylene.
9. The electric power cable as recited in claim 1, further comprising one or more third fillers positioned in one or more interstitial spaces between the one or three core units and the first layer of the sheathing unit, wherein the one or more third fillers are extended substantially along the longitudinal axis of the electric power 15 cable, wherein each of the one or more third fillers has a diameter in a range of about 6.2 millimeters to 11.0 millimeters and wherein each of the one or more third fillers is made of at least one material selected from a group consisting of polyvinyl chloride, polypropylene and polyethylene.
10. The electric power cable as recited in claim 1, further comprising an optical fiber 20 cable unit positioned in one or more interstitial spaces between the one or three core units and the first layer of the sheathing unit.