CA1133077A - Multiple section electric power line with single fluid cooling station - Google Patents
Multiple section electric power line with single fluid cooling stationInfo
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- CA1133077A CA1133077A CA338,406A CA338406A CA1133077A CA 1133077 A CA1133077 A CA 1133077A CA 338406 A CA338406 A CA 338406A CA 1133077 A CA1133077 A CA 1133077A
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- cooling fluid
- cable
- electric power
- power line
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Abstract
MULTIPLE SECTION ELECTRIC POWER
LINE WITH SINGLE FLUID COOLING STATION
ABSTRACT OF THE DISCLOSURE: A high voltage, electric power line comprising three cables, each having a cooling fluid channel in the conductor thereof and each comprising a plur-ality of sections interconnected by stop joints, the stop joints having inlets and outlets for the cooling fluid. The inlets are connected to a first header and the outlets are connected to a second header, and the headers are interconnect-ed by way of a heat exchanger and a pump to provide cooling fluid circulation through all the sections. An expansion tank may be connected to a conduit interconnecting the heat ex-changer to a header, and the cooling fluid may be the same as the cable insulating fluid.
LINE WITH SINGLE FLUID COOLING STATION
ABSTRACT OF THE DISCLOSURE: A high voltage, electric power line comprising three cables, each having a cooling fluid channel in the conductor thereof and each comprising a plur-ality of sections interconnected by stop joints, the stop joints having inlets and outlets for the cooling fluid. The inlets are connected to a first header and the outlets are connected to a second header, and the headers are interconnect-ed by way of a heat exchanger and a pump to provide cooling fluid circulation through all the sections. An expansion tank may be connected to a conduit interconnecting the heat ex-changer to a header, and the cooling fluid may be the same as the cable insulating fluid.
Description
The present invention relates to an electrical line for high voltage cables, especially cables operating at vol-tages higher than 200 kV, and, particularly, to an electrical line for operating at high voltages and cooled through the forced circulation of a fluid inside the eable forming said electrical line.
Preferably, but not exclusively, said electrical line I is formed by oil-filled cables, and the cooling fluid is the same as the fluid impregnating said oil-filled eables.
In reeent years, the teehnieal development in the field of the eleetric power transmission tended, both for under-ground and underwater laying, towards installations of inereas-ingly higher power eleetrical lines. This produces, in fact, several technieal and eeonomieal advantages, a reduetion in the number of the cables forming the electrical line with re-speet to the same transmitted power, a greater operating sim-plieity, a saving of time and manual labor in the installa-tion and in the maintenanee of the eleetrieal line, ete.
On the other hand, the power inerease gives rise to an important teehnieal problem, namely, the inerease of heat produeed in the eonduetors as the eurrent flows, that is, of the heat produced by Joule effect. Since the inherent dis-sipation of heat (through the insulated layers, the surfaces of the eable and the ambient) is always slow and small, the power inerease involves, with the same eonditions, an over-heating of the eable eonduetors.
Those skilled in the art know that a eonductor tem-perature of 85-90C is the maximum permissible in practiee, sinee higher values induee a rapid deerease of the insulation lifetime and a dangerous reduetion in eleetrieal safety eon-ditions. Consequently,the possibilities of inereasing the
Preferably, but not exclusively, said electrical line I is formed by oil-filled cables, and the cooling fluid is the same as the fluid impregnating said oil-filled eables.
In reeent years, the teehnieal development in the field of the eleetric power transmission tended, both for under-ground and underwater laying, towards installations of inereas-ingly higher power eleetrical lines. This produces, in fact, several technieal and eeonomieal advantages, a reduetion in the number of the cables forming the electrical line with re-speet to the same transmitted power, a greater operating sim-plieity, a saving of time and manual labor in the installa-tion and in the maintenanee of the eleetrieal line, ete.
On the other hand, the power inerease gives rise to an important teehnieal problem, namely, the inerease of heat produeed in the eonduetors as the eurrent flows, that is, of the heat produced by Joule effect. Since the inherent dis-sipation of heat (through the insulated layers, the surfaces of the eable and the ambient) is always slow and small, the power inerease involves, with the same eonditions, an over-heating of the eable eonduetors.
Those skilled in the art know that a eonductor tem-perature of 85-90C is the maximum permissible in practiee, sinee higher values induee a rapid deerease of the insulation lifetime and a dangerous reduetion in eleetrieal safety eon-ditions. Consequently,the possibilities of inereasing the
2. i ~330~7 transmitted power are linked, in general, to the possibilities of dissipating the heat produced in the conductors.
A provision which is often carried out in practice for underground cables, consists in causing a cooling fluid (air, water and so on) to flow in a channel surrounding the cable or adjacent to it. In this way, with the same tempera-ture of the conductors, the thermal gradient between the cable inside and the ambient in increased, thus favoring the radial dissipation of heat produced in the conductors.
A more efficient result is obtained by causing a forced flow of a cooling fluid inside the cable, i.e. by tak-ing away heat in the zone where the heat is produced. In practice, this is realized by causing a suitable fluid to flow in one or more longitudinal channels inside of, or adjacent to the conductors. In the case of oil-filled cables, the same impregnating fluid which is used in the paper insulation is generally utilized by causing said fluid to flow in a channel arranged longitudinally within each conductor.
In any case, however, cooling is carried out by causing a continuous forced flow of a suitable fluid, which is supplied at low temperature at a certain point in the cable and which is removed at another point in the cable at a higher tem-perature.
In the practice, a high voltage electrical line com-prises one or more cables. Because of the length of the elec-trical line, each cable is formed by a plurality of sections (each having a length of about one kilometer) connected by means of joints, known to those skilled in the art as "stop joints". Said joints connect adjacent cable sections elec-trically, but not hydraulically. As a matter of fact, each ofsaid stop joints is constituted by two parts, each being con-11~30~;~7 nected at one end of two adjacent cable sections and throughwhich it is possible to make the inlet and the outlet connec-tions for the cooling fluid.
Moreover, said cable sections are generally constitu-ted by a plurality of lengths (each having a length of some hun-dred meters) joined by usual joints (or straight joints), which both electrically and hydraulically connect adjacent cable lengths.
According to known techniques, the cooling is, there-fore, carried out by means of a continuous forced circulationof a fluid entering into the cable at a low temperature through the end of a section, and emerging at a higher temperature at the opposite end of the same section.
In the case of an electrical line comprising only one cable, each section is cooled independently from the other.
Therefore, the fluid emerging at the end of a cable section flows in an outer circuit along which a heat exchanger and a pump are installed, said heat exchanger reducing the fluid temperature to the desired value and said pump re-introducing said fluid under pressure at the opposite end of the same cable section.
In the case of an electrical line comprising a plur-ality of cables, it is common practice to extend the cooling of a cable section to the contiguous sections of the other cables by means of suitable hydraulic connections in series or in parallel.
Therefore, according to known technhque, each cooling circuit comprising a heat exchanger and a pump, provides for the thermal requirements of a contiguous section group, i.e.
of a group comprising a section for each of the cables forming part of the line. The pump capacity, the inlet and outlet tem-peratures of the fluid, the performance of the heat exchanger t7 7 and the chemical-physical properties of the fluid must be cal-culated according to the operating characteristics of the elec-trical line (section length, transmitted power, cable type, etc.).
From the foregoing, it is evident that an electrical line constructed according to known techniques, should be pro-vided, at least, with a pump, and a heat exchanger for each section (a line comprising a single cable) or for each section group (a line comprising a plurality of cables). However, this produces technical and economic drawbacks.
Firstly, if the electrical line is long, a great number of pumps and heat exchangers must be installed. In fact, it is to be considered that each cooling circuit should be pro-vided, as a rule, with two pumps and two heat exchangers, placed in parallel to each other, in order to avoid the risk of dan-gerous flow interruptions in case of troubles in a piece of the apparatus.
Secondly, (and perhaps this is the greater drawback) it is not always possible that the assembly of the apparatus (pumps, heat exchangers, valves, instrumentation, etc) relating to the cooling circuit may easily be arranged in the surround-ings of the section itself. In case of an urban installation, for example, great problems can rise, because of the absence of space for encasing the apparatus and the instrumentation, the necessity of efficacious safety measures, the annoying dis-sipation of heat in the ambient by the heat exchangers, the noise and the vibrations of the pumps, etc.
- It is clear that all these problems increase in pro-portion to the number of the pumping and cooling circuits nec-essary for meeting the thermal requirements of the whole elec-trical line.
~1330 .~7 A further drawback is the necessity of arranging along the whole high tension electrical line, a line of an-cillary electrical power for driving the pumps and for opera-ting the heat exchangers.
The drawbacks hereinbefore described are overcome by means of the high voltage electrical line according to the pre-sent invention.
In particular, an object of the present invention is a high voltage electrical line comprising one or more cables, each cable having at least a conductor insulated with impreg-nated paper or with an extruded synthetic material, each cable being constituted by a plurality of sections connected the one to the other by means of stop joints, each section being pro-vided with at least an inner longitudinal channel appropriate for the flow of a cooling fluid for its whole length, the in-let for said fluid being at one end of the section and the out-let, at the opposite end of the same section, characterized by the fact that the inlet for said fluid in each section is con-nected to a first header, connected by means of a conduit to a , second header linked at the outlet for said fluid of each sec-tion and that said conduit has installed, in series with each other, at least a heat exchanger and a pump having its delivery side connected to said first header and having its suction side connected to said second header.
Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment thereof, which description should be considered in conjunction with the accompanying drawing, the single figure of which is a schematic diagram of a prefer~ed embodiment of a three-phase electrical line incorporating the invention.
The example of the invention illustrated in the ~W07~
drawing relates to a three-phase electrical line, i.e. to an electrical line comprising three single-core cables. Moreover, each cable is of the oil-filled type, that is comprises a con-duetor insulated with impregnated paper and traversed by a longitudinal channel in which, as the cooling fluid, flows the same fluid as is used to impregnate the paper.
It will be understood that the present invention may also be advantageously applied to an electrical line comprising a different number of cables, single-core cables or not, and which may also not be of the oil-filled type.
From the drawing it will be seen that the high vol-tage electrical line L comprises the cables Cl, C2 and C3.
Each of said cables is of the oil-filled type and therefore, comprises a eonductor insulated with paper impregnated with, for example, decylbenzene or dodecylbenzene and a longitudinal channel within the conductor for the flow of the cooling fluid, which is the same as the impregnating fluid. Each of said cables Cl, C2 and C3 is constituted by a plurality of sections conneeted one to the other by means of stop joints.
In the drawing, only the cable Cl is represented in detail between the two sealing ends Tl and T2. The said seal-ing ends are known per se and the cooling fluid is also made to - flow in the sealing ends Tl and T2.
Said cable Cl is constituted by the sections Sl, S2, S3, S4, S5 and S6 which are connected one to the other by means of stop joints Gl-G5. Obviously, the number of said seetions can vary according to the length and the particular operating requirements of the electrical line.
The length of each section is about of one kilometer.
However, as the lengths of oil-filled cables are generally of several hundred meters, each section consists of a plurality of 30~7'7 lengths connected one to another by means of usual joints, also called straight joints (not shown in the drawing). Said straight joints, unlike said stop joints, both electrically and hydraulically connect adjacent cable lenyths.
Finally, in the case of a particularly long electrical line, technical reasons can make it desirable to divide the line into two or more parts, each of them cooled according to the present invention.
Regarding the cables C2 and C3, for sake of simpli-city, only the corresponding sections S7 and S8 with the re-lated stop joints G6, G7, G8 and Gg are shown.
Each stop joint, as is known to those skilled in the art, guarantees the electrical connection between two adjacent cable sections, but prevents the passage of fluid from one section to the other. In fact, each of said stop joints is made by two hydraulically separated parts, for the stop joint ~1 the parts la and lb, for the stop joint G2 the parts 2a and 2b, for the stop joint G3 the parts 3a and 3b, for the stop jcint G4 the parts 4a and 4b, for the stop joint G5 the parts 5a and 5b, for the stop joint G6 the parts 6a and 6b, for the stop joint G7 the parts 7a and 7b, for the stop joint G8 the parts 8a and 8b, and for the stop joint G9 the parts 9a and 9b.
Through each of said parts, connected at one end of a cable section, there is the inlet or the outlet for the cool-ing fluid flowing in the inner longitudinal channel of the con-ductor. With reference to the drawing, the parts marked with (a) are used for the cooling fluid inlet, while the parts marked with (b) are used for the cooling fluid outlet.
A first and a second header, respectively TCl and TC2, are arranged in parallel with the electrical line L con-stituted by cables Cl, C2 and C3. Said headers TCl and TC2 are connected to each other by means of a conduit TC3 on which the heat exchanger SC and the pump P are installed, in series one to the other. Moreover, a tank SE containing the cooling fluid i~ connected to said conduit TC3.
Said first header TCl is connected to the delivery side of said pump P, while said second header TC2 is connected to the suction side of said pump P. Therefore, a fluid at low temperature and at the pressure generated by the pump P flows in said first header TCl.
Said fluid is supplied,through appropriate offtakes (Dl, D2, D3, D4, D5 and D6), by said first header TCl to one end of each of the cable sections Sl, S2, S3, S4, S5 and S6, respectively through the parts la of stop joint Gl, 2a of stop joint G2, 3a of stop joint G3, 4a of stop joint G4, 5a of stop joint G5, and into the sealing end T2.
The fluid emerging from the opposite ends of the 1' 2' S3, S4, S5 and S6 (through the sealing end Tl and the parts lb of the stop joint Gl, 2b of stop joint G2, 3b of stop joint G3, 4b of stop joint G and 5b of stop joint G5) is collected, through appropriate offtakes (D7, D8, Dg, Dlo, Dll and D12) in the second header TC2. Therefore, in this header TC2, the fluid flows at a lower pressure and at a high-er temperature with respect to the pressure and to the temper-ature of the same fluid flowing in the first header TCl.
The fluid flowing in said second header TC2 is piped by means of the conduit TC3 towards the heat exchanger SC (work-ing by water, air or any other known system) which reduces the fluid temperature to a desired value. Said fluid is then de-livered, by means of the pump P, into the first header TCl.
The tank SE of the cooling fluid is connected to said conduit TC3. Said tank SE is used either for reconstituting the cooling fluid in case it is dissipated outside the tank SE or for compensating the volume variations of the fluid according to the temperature variations.
The conduit TC3, connecting said first and second headers TCl and TC2, can be arranged between two any points of said first and second header. The arrangement, illustrated in the drawing, of the ends of said conduit TC3 between the offtakes D3 and D4 of the first header TCl and between the off-takes Dlo and Dll of the second header TC2 is given only as an example.
The arrows shown in the drawing indicate the fluid flow in the first and in the second header, in the conduit connect-ing said first and second header, in the cable sections, in the - heat exchanger and in the pump.
With reference to the lengths of the cables C2 and C3, which together with cable Cl constitute the three-core elec-trical line L, it can be observed how the cooling of the three contiguous sections S , S7 and S8 is made.
The fluid, drawn from the offtake D4 of the first header TCl is shared among the ends of each section S4, S7 and S8, through the parts 4a, 7a and 9a respectively of the stop joints G4, G7 and Gg. The fluid flows in the above said three sections and outlets at their opposite ends through the parts 8b, 6b and 3b respectively of the joints G8, G6 and G3. Said fluid then flows through the offtake Dlo into the second head-er TC2.
It is clear that the delivery of the pump, the sizes of the first and second header and of the conduit connecting the same, the inlet and outlet temperatures of the fluid through the ends of each cable section and the performances of the heat exchanger, should be determined for each installation 10 .
1133C~77 according to the operating characteristics of the electrical line (transmitted power, section number, cable type, etc.).
From the foregoing it is clear that the advantages of the high tension electrical line according to the present in-vention, derive from the adoption of a header TCl from which the cooling fluid under pressure and at a low temperature is delivered into the inner longitudinal channels of the various cable sections and from a header TC2 in which the same cooling fluid at a lower pressure and at a higher temperature is de-livered from the cable sections.
These operations are accomplished by employing only one pump and one heat exchanger. This provides a great tech-nical simplification and a great economic saving with respect to known techniques.
On the other hand, the heat exchanger, the pump and the tank for the fluid, all the control apparatus and the in-strumentation (not shown) can be arranged at any point on the electrical line. This permits selection of the more suitable position which is easier to reach, or is more protected or is provided with infrastructures.
Although preferred embodiments of the present in-vention have been described and illustrated, it will be appar-ent to those skilled in the art that various modifications may be made without departing from the principles of the invention.
A provision which is often carried out in practice for underground cables, consists in causing a cooling fluid (air, water and so on) to flow in a channel surrounding the cable or adjacent to it. In this way, with the same tempera-ture of the conductors, the thermal gradient between the cable inside and the ambient in increased, thus favoring the radial dissipation of heat produced in the conductors.
A more efficient result is obtained by causing a forced flow of a cooling fluid inside the cable, i.e. by tak-ing away heat in the zone where the heat is produced. In practice, this is realized by causing a suitable fluid to flow in one or more longitudinal channels inside of, or adjacent to the conductors. In the case of oil-filled cables, the same impregnating fluid which is used in the paper insulation is generally utilized by causing said fluid to flow in a channel arranged longitudinally within each conductor.
In any case, however, cooling is carried out by causing a continuous forced flow of a suitable fluid, which is supplied at low temperature at a certain point in the cable and which is removed at another point in the cable at a higher tem-perature.
In the practice, a high voltage electrical line com-prises one or more cables. Because of the length of the elec-trical line, each cable is formed by a plurality of sections (each having a length of about one kilometer) connected by means of joints, known to those skilled in the art as "stop joints". Said joints connect adjacent cable sections elec-trically, but not hydraulically. As a matter of fact, each ofsaid stop joints is constituted by two parts, each being con-11~30~;~7 nected at one end of two adjacent cable sections and throughwhich it is possible to make the inlet and the outlet connec-tions for the cooling fluid.
Moreover, said cable sections are generally constitu-ted by a plurality of lengths (each having a length of some hun-dred meters) joined by usual joints (or straight joints), which both electrically and hydraulically connect adjacent cable lengths.
According to known techniques, the cooling is, there-fore, carried out by means of a continuous forced circulationof a fluid entering into the cable at a low temperature through the end of a section, and emerging at a higher temperature at the opposite end of the same section.
In the case of an electrical line comprising only one cable, each section is cooled independently from the other.
Therefore, the fluid emerging at the end of a cable section flows in an outer circuit along which a heat exchanger and a pump are installed, said heat exchanger reducing the fluid temperature to the desired value and said pump re-introducing said fluid under pressure at the opposite end of the same cable section.
In the case of an electrical line comprising a plur-ality of cables, it is common practice to extend the cooling of a cable section to the contiguous sections of the other cables by means of suitable hydraulic connections in series or in parallel.
Therefore, according to known technhque, each cooling circuit comprising a heat exchanger and a pump, provides for the thermal requirements of a contiguous section group, i.e.
of a group comprising a section for each of the cables forming part of the line. The pump capacity, the inlet and outlet tem-peratures of the fluid, the performance of the heat exchanger t7 7 and the chemical-physical properties of the fluid must be cal-culated according to the operating characteristics of the elec-trical line (section length, transmitted power, cable type, etc.).
From the foregoing, it is evident that an electrical line constructed according to known techniques, should be pro-vided, at least, with a pump, and a heat exchanger for each section (a line comprising a single cable) or for each section group (a line comprising a plurality of cables). However, this produces technical and economic drawbacks.
Firstly, if the electrical line is long, a great number of pumps and heat exchangers must be installed. In fact, it is to be considered that each cooling circuit should be pro-vided, as a rule, with two pumps and two heat exchangers, placed in parallel to each other, in order to avoid the risk of dan-gerous flow interruptions in case of troubles in a piece of the apparatus.
Secondly, (and perhaps this is the greater drawback) it is not always possible that the assembly of the apparatus (pumps, heat exchangers, valves, instrumentation, etc) relating to the cooling circuit may easily be arranged in the surround-ings of the section itself. In case of an urban installation, for example, great problems can rise, because of the absence of space for encasing the apparatus and the instrumentation, the necessity of efficacious safety measures, the annoying dis-sipation of heat in the ambient by the heat exchangers, the noise and the vibrations of the pumps, etc.
- It is clear that all these problems increase in pro-portion to the number of the pumping and cooling circuits nec-essary for meeting the thermal requirements of the whole elec-trical line.
~1330 .~7 A further drawback is the necessity of arranging along the whole high tension electrical line, a line of an-cillary electrical power for driving the pumps and for opera-ting the heat exchangers.
The drawbacks hereinbefore described are overcome by means of the high voltage electrical line according to the pre-sent invention.
In particular, an object of the present invention is a high voltage electrical line comprising one or more cables, each cable having at least a conductor insulated with impreg-nated paper or with an extruded synthetic material, each cable being constituted by a plurality of sections connected the one to the other by means of stop joints, each section being pro-vided with at least an inner longitudinal channel appropriate for the flow of a cooling fluid for its whole length, the in-let for said fluid being at one end of the section and the out-let, at the opposite end of the same section, characterized by the fact that the inlet for said fluid in each section is con-nected to a first header, connected by means of a conduit to a , second header linked at the outlet for said fluid of each sec-tion and that said conduit has installed, in series with each other, at least a heat exchanger and a pump having its delivery side connected to said first header and having its suction side connected to said second header.
Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment thereof, which description should be considered in conjunction with the accompanying drawing, the single figure of which is a schematic diagram of a prefer~ed embodiment of a three-phase electrical line incorporating the invention.
The example of the invention illustrated in the ~W07~
drawing relates to a three-phase electrical line, i.e. to an electrical line comprising three single-core cables. Moreover, each cable is of the oil-filled type, that is comprises a con-duetor insulated with impregnated paper and traversed by a longitudinal channel in which, as the cooling fluid, flows the same fluid as is used to impregnate the paper.
It will be understood that the present invention may also be advantageously applied to an electrical line comprising a different number of cables, single-core cables or not, and which may also not be of the oil-filled type.
From the drawing it will be seen that the high vol-tage electrical line L comprises the cables Cl, C2 and C3.
Each of said cables is of the oil-filled type and therefore, comprises a eonductor insulated with paper impregnated with, for example, decylbenzene or dodecylbenzene and a longitudinal channel within the conductor for the flow of the cooling fluid, which is the same as the impregnating fluid. Each of said cables Cl, C2 and C3 is constituted by a plurality of sections conneeted one to the other by means of stop joints.
In the drawing, only the cable Cl is represented in detail between the two sealing ends Tl and T2. The said seal-ing ends are known per se and the cooling fluid is also made to - flow in the sealing ends Tl and T2.
Said cable Cl is constituted by the sections Sl, S2, S3, S4, S5 and S6 which are connected one to the other by means of stop joints Gl-G5. Obviously, the number of said seetions can vary according to the length and the particular operating requirements of the electrical line.
The length of each section is about of one kilometer.
However, as the lengths of oil-filled cables are generally of several hundred meters, each section consists of a plurality of 30~7'7 lengths connected one to another by means of usual joints, also called straight joints (not shown in the drawing). Said straight joints, unlike said stop joints, both electrically and hydraulically connect adjacent cable lenyths.
Finally, in the case of a particularly long electrical line, technical reasons can make it desirable to divide the line into two or more parts, each of them cooled according to the present invention.
Regarding the cables C2 and C3, for sake of simpli-city, only the corresponding sections S7 and S8 with the re-lated stop joints G6, G7, G8 and Gg are shown.
Each stop joint, as is known to those skilled in the art, guarantees the electrical connection between two adjacent cable sections, but prevents the passage of fluid from one section to the other. In fact, each of said stop joints is made by two hydraulically separated parts, for the stop joint ~1 the parts la and lb, for the stop joint G2 the parts 2a and 2b, for the stop joint G3 the parts 3a and 3b, for the stop jcint G4 the parts 4a and 4b, for the stop joint G5 the parts 5a and 5b, for the stop joint G6 the parts 6a and 6b, for the stop joint G7 the parts 7a and 7b, for the stop joint G8 the parts 8a and 8b, and for the stop joint G9 the parts 9a and 9b.
Through each of said parts, connected at one end of a cable section, there is the inlet or the outlet for the cool-ing fluid flowing in the inner longitudinal channel of the con-ductor. With reference to the drawing, the parts marked with (a) are used for the cooling fluid inlet, while the parts marked with (b) are used for the cooling fluid outlet.
A first and a second header, respectively TCl and TC2, are arranged in parallel with the electrical line L con-stituted by cables Cl, C2 and C3. Said headers TCl and TC2 are connected to each other by means of a conduit TC3 on which the heat exchanger SC and the pump P are installed, in series one to the other. Moreover, a tank SE containing the cooling fluid i~ connected to said conduit TC3.
Said first header TCl is connected to the delivery side of said pump P, while said second header TC2 is connected to the suction side of said pump P. Therefore, a fluid at low temperature and at the pressure generated by the pump P flows in said first header TCl.
Said fluid is supplied,through appropriate offtakes (Dl, D2, D3, D4, D5 and D6), by said first header TCl to one end of each of the cable sections Sl, S2, S3, S4, S5 and S6, respectively through the parts la of stop joint Gl, 2a of stop joint G2, 3a of stop joint G3, 4a of stop joint G4, 5a of stop joint G5, and into the sealing end T2.
The fluid emerging from the opposite ends of the 1' 2' S3, S4, S5 and S6 (through the sealing end Tl and the parts lb of the stop joint Gl, 2b of stop joint G2, 3b of stop joint G3, 4b of stop joint G and 5b of stop joint G5) is collected, through appropriate offtakes (D7, D8, Dg, Dlo, Dll and D12) in the second header TC2. Therefore, in this header TC2, the fluid flows at a lower pressure and at a high-er temperature with respect to the pressure and to the temper-ature of the same fluid flowing in the first header TCl.
The fluid flowing in said second header TC2 is piped by means of the conduit TC3 towards the heat exchanger SC (work-ing by water, air or any other known system) which reduces the fluid temperature to a desired value. Said fluid is then de-livered, by means of the pump P, into the first header TCl.
The tank SE of the cooling fluid is connected to said conduit TC3. Said tank SE is used either for reconstituting the cooling fluid in case it is dissipated outside the tank SE or for compensating the volume variations of the fluid according to the temperature variations.
The conduit TC3, connecting said first and second headers TCl and TC2, can be arranged between two any points of said first and second header. The arrangement, illustrated in the drawing, of the ends of said conduit TC3 between the offtakes D3 and D4 of the first header TCl and between the off-takes Dlo and Dll of the second header TC2 is given only as an example.
The arrows shown in the drawing indicate the fluid flow in the first and in the second header, in the conduit connect-ing said first and second header, in the cable sections, in the - heat exchanger and in the pump.
With reference to the lengths of the cables C2 and C3, which together with cable Cl constitute the three-core elec-trical line L, it can be observed how the cooling of the three contiguous sections S , S7 and S8 is made.
The fluid, drawn from the offtake D4 of the first header TCl is shared among the ends of each section S4, S7 and S8, through the parts 4a, 7a and 9a respectively of the stop joints G4, G7 and Gg. The fluid flows in the above said three sections and outlets at their opposite ends through the parts 8b, 6b and 3b respectively of the joints G8, G6 and G3. Said fluid then flows through the offtake Dlo into the second head-er TC2.
It is clear that the delivery of the pump, the sizes of the first and second header and of the conduit connecting the same, the inlet and outlet temperatures of the fluid through the ends of each cable section and the performances of the heat exchanger, should be determined for each installation 10 .
1133C~77 according to the operating characteristics of the electrical line (transmitted power, section number, cable type, etc.).
From the foregoing it is clear that the advantages of the high tension electrical line according to the present in-vention, derive from the adoption of a header TCl from which the cooling fluid under pressure and at a low temperature is delivered into the inner longitudinal channels of the various cable sections and from a header TC2 in which the same cooling fluid at a lower pressure and at a higher temperature is de-livered from the cable sections.
These operations are accomplished by employing only one pump and one heat exchanger. This provides a great tech-nical simplification and a great economic saving with respect to known techniques.
On the other hand, the heat exchanger, the pump and the tank for the fluid, all the control apparatus and the in-strumentation (not shown) can be arranged at any point on the electrical line. This permits selection of the more suitable position which is easier to reach, or is more protected or is provided with infrastructures.
Although preferred embodiments of the present in-vention have been described and illustrated, it will be appar-ent to those skilled in the art that various modifications may be made without departing from the principles of the invention.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. High voltage electric power line comprising one or more cables, each cable comprising a conductor surrounded by insulation and the conductor having at least an inner longitud-inal channel for the flow of a cooling fluid therein, each cable comprising a plurality of sections interconnected by way of stop joints and each section having an inlet at one end there-of for receiving the cooling fluid and supplying it to the con-ductor channel and having an outlet at the opposite end thereof for removing the cooling fluid from the conductor channel, first header means interconnecting a plurality of the inlets of sec-tions, second header means interconnecting a plurality of the outlets of the same sections and heat exchanger means and pump means connected by conduit means between said first header and said second header for removing said cooling fluid from said second header and supplying said cooling fluid to said first header under pressure and at a temperature differing from the temperature thereof in said second header.
2. High voltage electric power line as set forth in claim 1 further comprising an expansion tank for said cool-ing fluid connected to one of said means for receiving, and storing said cooling fluid.
3. High voltage electric power line as set forth in claim 2 wherein said tank is connected to said conduit means.
4. High voltage electric power line as set forth in claims 1 or 2 wherein said insulation is impregnated with a fluid which is the same as said cooling fluid.
5. High voltage electric power line as set forth in claim 1 wherein there are three cables, each cable being terminated at its opposite ends by sealing ends and wherein the inlet of each section of each cable is connected to said first header and the outlet of each section of each cable is connected to said second header.
6. High voltage electric power line as set forth in claim 5 wherein each sealing end has a connection communi-cating with the cooling channel in the conductor of the cable to which it is connected and wherein the connections of the sealing ends at one end of the cables are connected to said first header so that cooling fluid flows from said last-men-tioned sealing ends to the outlets of sections adjacent thereto and the connections of the sealing ends at the opposite ends of the cables are connected to said second header so that cooling fluid flows from the inlets of sections adjacent to said last-mentioned sealing ends to said second header.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT29065A/78 | 1978-10-25 | ||
| IT2906578A IT1160007B (en) | 1978-10-25 | 1978-10-25 | Multiple section electric power line with cooling station - has heat exchanger with inlet and outlet headers interconnected by pump and conduit supplying coolant along conductor channel (BR 17.6.80) |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1133077A true CA1133077A (en) | 1982-10-05 |
Family
ID=11226069
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA338,406A Expired CA1133077A (en) | 1978-10-25 | 1979-10-25 | Multiple section electric power line with single fluid cooling station |
Country Status (4)
| Country | Link |
|---|---|
| BR (1) | BR7906794A (en) |
| CA (1) | CA1133077A (en) |
| ES (1) | ES485628A1 (en) |
| IT (1) | IT1160007B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5442131A (en) * | 1993-07-23 | 1995-08-15 | Borgwarth; Dennis | High energy coaxial cable cooling apparatus |
-
1978
- 1978-10-25 IT IT2906578A patent/IT1160007B/en active
-
1979
- 1979-10-22 BR BR7906794A patent/BR7906794A/en unknown
- 1979-10-25 CA CA338,406A patent/CA1133077A/en not_active Expired
- 1979-10-25 ES ES485628A patent/ES485628A1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5442131A (en) * | 1993-07-23 | 1995-08-15 | Borgwarth; Dennis | High energy coaxial cable cooling apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| IT7829065A0 (en) | 1978-10-25 |
| BR7906794A (en) | 1980-06-17 |
| ES485628A1 (en) | 1980-05-16 |
| IT1160007B (en) | 1987-03-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |