TWI651910B - Safe high voltage transmission system and equivalent current transmission cable - Google Patents

Abstract

The invention provides a safe high-voltage electric transmission system and an equal current transmission cable thereof, and the technical features thereof mainly include an equal current transmission cable and an input and output transformer; the current transmission cable includes a power input terminal and a power supply output terminal. And a three-phase transmission circuit is divided into three unidirectional circuit types, each unidirectional circuit includes a conductive core wire and a conductive outer tube disposed in a coaxial inner periphery, and the two are spaced apart to form an annular insulating portion, and the conductive core wire The transmission direction of the conductive outer tube is opposite to each other and the amount of current supplied by the two is equal; the input transformer is connected to the power supply input end, and the input transformer comprises three phase isolated input transformer circuit units, and the output transformer is connected At the power supply output, the output transformer includes three phase isolated output transformer circuit units.

Description

Safety high voltage electric transmission system and its equal current transmission cable

The present invention relates to an electric power transmission system; and more particularly to an innovative high-voltage electric transmission system and an innovative structural type revealer of the same current transmission cable.

In today's social environment, people's daily lives must rely on various electrical products to achieve various tasks and purposes. Therefore, power supply has become an indispensable project, and the power transmission part of the present invention is a power supply. An important project in the system that cannot be ignored.

However, people familiar with power transmission should find it easy to find that the following shortcomings and problems still exist in the conventional power transmission system:

1. The construction cost is quite expensive: if the ultra-high voltage 161 or 345KV system is used, only a single high-voltage electric tower may cost tens of millions of yuan to build, and the land occupation is broad, and the land acquisition cost is relatively high. If it is to change the high-voltage cable, it is necessary to build an underground tunnel, and the cost is also quite high.

2. There is a high degree of danger: if the type of power transmission and distribution system is in the form of high-voltage electric tower, it will not only affect the environment, but also the hidden dangers of human and animal electric shock and the disconnection crisis. Electromagnetic waves cause interference and injury to humans and animals. This is the main reason why residents around the transmission line have always hated and opposed it. Although the power company usually claims that the distance is 8.5 meters away from the transmission line, it is a safe distance for radio waves, but some foreign countries. The research report pointed out that it is more appropriate to take a distance of 100 meters.

3. The cost of curing is high and there is a high risk of curing. The high-voltage transmission circuit usually achieves insulation through the arrangement of ceramic barriers. The temperature resistance and insulation effect of the ceramic insulators are really excellent, but its existence is worrying. From the surface dust, the dust in the air mostly contains conductive carbon particles and dust which may cause chemical components such as flashover breakdown, which will gradually adhere and accumulate on the surface of the ceramic occlusion, and because of the high Piezoelectricity has a strong electric field attraction, which makes the aforementioned dust adhesion phenomenon be strengthened, causing natural forces such as rain and strong winds to not easily clean the dust on the surface of the ceramic etchant, and the fine water droplets of the rain will make the ceramic The micro-conductive dust on the surface of the occlusion is connected to form an electrical conductor, which leads to leakage. This leakage is also a waste of energy. For example, if the leakage of each ceramic etch is 0.005A, then About 2,000 ceramic entanglements per 100 kilometers of transmission lines will generate electrical losses of about 3,450 KW (kilowatts); Electric excessive, often sent a helicopter to dust, but the state will not suspend transmission, imagine there is extreme risk this work, apparently also a major cost-consuming and worries.

4. Poor transmission effect: In terms of transmission effect, the most serious problem at present should be line voltage drop problem and power loss. However, the current efficiency of transmission and distribution systems in the world is actually in a low state. After a hundred years, there is still no ideal improvement plan. Among them, the line inductance is the most serious problem. The longer the line is, the stronger the inductive resistance is. Even if it is an underground cable, there is still a great sense of resistance. Briefly, as shown in Fig. 7, when a current 81 is passed through a transmission line 80, an induced electromagnetic field 82 is formed around the line diameter, and the induced electromagnetic field 82 relatively resists passing through the transmission line. Current 81 in the middle (Note: The outer cladding of the transmission line 80 is also in the same direction as the current 81 in the transmission line even if the current 81B with ground leakage is the same (ie, the same direction as the neutral line), so the two cannot The two cancel each other, and the intensity of the induced electromagnetic field 82 is not reduced. Therefore, the interaction between the current and the coil is called the electrical inductive reactance, that is, the inductance in the circuit. Then, how serious is the line inductance? In terms of specific data, the long-distance transmission in continental countries is quite common. The transmission lines are as long as 500 kilometers. Based on the aforementioned inductive reactance, the transmission line is usually changed to 50Hz. In order to reduce the inductance against voltage drop, but the lower the transmission frequency, the transformer cost and the space occupied by the substation will increase proportionally. In terms of China's 60Hz three-phase 161KV (kV) high-voltage tower transmission line If it is simplified to three lines for explanation, the circuit structure of the three-wire transmission can be shown in FIG. 8. The three lines arranged in the upper and lower intervals respectively represent the transmission lines 80 of different phases (ie, R, S, T). The two ends of each transmission line 80 are electrically connected by a transformer 83, 84, respectively, to control the transmission direction of each transmission line 80 by the transformers 83, 84 (shown by the dotted arrow in the figure) When the 1 million KVA is full load, the power receiving end at 100 km may only obtain a voltage of about 100.69 KV (kV), which seems to reduce the effective backup capacity of the power plant directly. 37%; but, right To understand the power transmission and distribution experts, it should be known that the voltage drop rate of the wire reactance does not completely represent the loss rate of the electric energy. Of course, the above argument is assumed that under the condition of non-pre-current load, the high-voltage capacitor has not been boosted or In the case before the thickening of the line, once the capacitor is connected in parallel to the receiving end and the resonance is boosted, the voltage drop rate will of course be improved immediately, but this requires a relatively large increase in cost, and the power factor is usually compensated to 70 to 80%. Appropriate, for example, if the compensation is 70.7%, which is equal to the pressure drop of 13.09%, then only about 92,600 KVAR (thousands of power, the unit of virtual power) is required, but if you want to increase the compensation to 100%, It is necessary to set a capacitor of about 363,000 KVAR, the cost must be increased several times, and the overall transmission line must add the amount of current to deliver the forward current. The power factor is used to compensate the required facilities, which inevitably consumes huge costs. In addition, it is invalid. About 1% of the power value will inevitably become the actual electrical energy consumption loss. In the case of the above-mentioned 1 million KVA power delivery, the actual increased electrical loss will reach About 1363KW or so, this is obviously a loss that cannot be ignored; in addition, the difficulty in regulating the pressure drop is caused by considerable power consumption, although most of the load is lagging current is still fortunate, but in the peak period of power supply, often due to factory rest However, the power factor improvement capacitor does not necessarily turn off, resulting in the load of the front current. At this time, the power supply terminal is close to the standard voltage, but the power receiving terminal is boosted due to the LC resonance factor. Perhaps the reader thinks that the electrical equipment of each household is used. The problem of burnout due to the aforementioned boosting problem is not large, but in fact, the substation of the power company is seriously damaged because of this problem, because it will greatly increase the copper loss of the transmission and distribution circuit, which may increase by 0.5%. To 1.5% (the most conservative estimate), if the capacity of a substation of 1 million KW is used, it will lose 15,000 KW of electricity. If it continues to operate for 6 hours at night, it will lose more than 60,000 KWH (degrees). The electric energy is calculated at 2 yuan per kWh, which is equivalent to a loss of 120,000 yuan overnight. This shows that the biggest victim is actually a power company; and another serious problem is: a transformer that has been greatly depleted in the substation. Home, more likely because of long high temperature, magnetic overload phenomenon early damage and shorten the life of the relative increase operating costs.

5, the worry of eDonkey damage: usually in the eight lines of high-voltage power transmission lines, the top two lines are lightning protection ground lines, this part of the installation is also a major project and cost, when high-voltage electricity When the transmission line is subjected to thunder, the lightning protection ground line should protect the high-voltage transmission line below it. However, in fact, there are more than ten or more serious lightning damages in China every year, and thousands of times. The reason for the lightning loss is that the lightning protection ground wire itself has a great grounding inductance and grounding resistance, since the lightning occurs for a very short time (about 50 US to 70 US, that is, about tens of millions of seconds) Current (about 2,000 to 200,000 amps, voltage is 3 million to 500 million volts), because its spike current can reach tens of thousands of amps, so the lightning resistance ground with high inductance can only be in very weak electricity. In the case of 殛, the protection function is exerted, but when a strong thunder is encountered, the flashover discharge may still hit the high-voltage transmission line, wherein the specific inductive reactance value of the lightning protection ground wire is calculated by 20UH, and the grounding resistance is Treated as perfect 0 ohm, then its The flow can be 10,000 amps, but because it is a pointed current, if it is calculated by the initial 0.1 US, there is about 6283 kV (KV), so of course, it will cause a power jump; therefore, it can be known that the grounding inductance and grounding can be The resistance is reduced by more than 100 times to significantly increase the protection effect, but this part is obviously impossible to achieve for the conventional structure; this power damage has been a pain in many industries, especially during the thunderstorm season. In the case of sudden power failure and then resume power transmission, this is usually caused by the mechanism of automatic instantaneous trip protection during power failure. However, in this process, although the motor system is protected due to tripping, many consumers IC chips in electronic systems and equipment, etc., have often been severely damaged and must be repaired or replaced because the electronic or computer equipment has been damaged by high-voltage pulse currents at the moment before the aforementioned power outages. Kinds of damage can be large or small for the industry. The main point is that there is often no way to claim compensation, so equipment is shut down, work procedures and delivery time are delayed, resulting in unnecessary but significant losses. .

The additional point is that the above example illustrates the calculation of the wire diameter only under the condition of the safe current amount. Of course, the power company usually thickens the wire diameter of the transmission line several times or more to reduce the pressure drop rate. However, in principle, the line cost will also increase several times, and there is a problem that the transmission cable installation cost is greatly increased.

Therefore, in view of the problems existing in the above-mentioned conventional high-voltage electric transmission technology, how to develop an innovative structure that can be more ideal and practical, and it is necessary for the relevant industry to think again about the goals and directions of the breakthrough; in view of this, The inventor has been engaged in the manufacturing development and design experience of related products for many years. After detailed design and careful evaluation of the above objectives, the inventor has finally obtained the practical invention.

The main object of the present invention is to provide a safe high-voltage electric transmission system and its equal current transmission cable, and the technical problem to be solved is to develop a new safe high-voltage electric transmission which is more ideal and practical. The system and its equal current transmission cable are considered as innovative breakthroughs.

The technical feature of the present invention is mainly that the safe high-voltage electric transmission system comprises: a first-current current transmission cable, which is a linear extension type, including a power supply input end and a power supply output end, and the current transmission cable The line system divides a three-phase transmission circuit into three unidirectional circuit types, each of the unidirectional circuits includes a conductive core wire and a conductive outer tube disposed in a coaxial inner periphery, and the conductive core wire and the conductive outer tube An annular insulating portion is formed at a distance from each other, and wherein the conductive core and the conductive outer tube have opposite transmission directions and the amount of the two currents is equal; an input transformer is electrically connected The power input terminal of the current transmission cable, the input transformer includes an isolated input transformer circuit unit having three phases, and the two extremes of the isolated input transformer circuit unit of the phase and the current input are respectively The conductive core wire and the conductive outer tube of each unidirectional circuit provided by the cable are electrically connected; and an output transformer is electrically connected to the power supply of the current transmission cable. The output end includes an isolated output transformer circuit unit having three phases, and the two extremes of the isolated output transformer circuit unit of the phase are respectively arranged with the respective current transmission cables The conductive core wire and the conductive outer tube of the loop are electrically connected.

The main effects and advantages of the present invention are that it can greatly reduce the cost of power transmission system construction, no electromagnetic wave radiation state and electric shock hazard, greatly reduce the loop inductance, improve the safety and reliability of the high voltage transmission system, and reduce the transformer installation cost and the cost. Need space and other practical and progressive.

Please refer to the first, second, and third figures, which are preferred embodiments of the safe high-voltage power transmission system and its equal current transmission cable of the present invention, but the embodiments are for illustrative purposes only, and are used in patent applications. Not subject to this structure.

The safety high-voltage electric transmission system A comprises the following structure: a first-phase current transmission cable 10, which is a linear extension type, including a power supply input terminal 11 and a power supply output terminal 12, and the current transmission cable 10 A three-phase transmission circuit is divided into three unidirectional circuit types, each of which includes a conductive core 13 and a conductive outer tube 14 disposed in a coaxial inner periphery, and the conductive core 13 and the conductive The outer tubes 14 are spaced apart from each other to form an annular insulating portion 15, and wherein the conductive cores 13 and the conductive outer tubes 14 are opposite to each other in the power transmission directions L1 and L2 (as shown in FIG. 7) and the two are transported. The electric current is in an equal relationship; an input transformer 20 is electrically connected to the power supply input terminal 11 of the current transmission cable 10, and the input transformer 20 includes an isolated type having three phases (ie, R, S, T). The input transformer circuit unit 21, the two poles 213 and 215 of the isolated input transformer circuit unit 21 of the phase are respectively connected with the conductive core wires 13 of the unidirectional circuits provided by the current transmission cable 10 and the conductive The outer tube 14 is electrically connected; an output transformer 30 is The connection state is set at the power supply output terminal 12 of the current transmission cable 10, and the output transformer 30 includes an isolated output transformer circuit unit 31 having three phases, and two of the isolated output transformer circuit units 31 of the phase. The poles 312 and 314 are electrically connected to the conductive core 13 and the conductive outer tube 14 of each of the unidirectional circuits provided in the current transmission cable 10.

By the above-mentioned structural composition and technical features, the conductive wires 13 and the conductive outer tubes 14 of the current transmission cable 10 of the present invention are opposite to each other in the transmission directions L1 and L2, and the amount of current delivered is equal. One of the main technical features is that the inductive reactance of the high-voltage electric transmission line can be greatly reduced, and the principle of achievement is as shown in Fig. 6, because the transmission direction L1 of the conductive core 13 and the transmission direction L2 of the conductive outer tube 14 are mutually On the contrary, the inductive electromagnetic field directions R1 and R2 generated when the current passes through are also inversely related, that is, the induced electromagnetic fields generated when the conductive core 13 and the conductive outer tube 14 are both transmitted are offset each other. A state in which the inductance is greatly reduced and a state of zero electromagnetic radiation is achieved. On the other hand, the current transmission cable 10 disclosed in the present invention is a type in which a three-phase transmission circuit is divided into three unidirectional circuits, and each unidirectional circuit is provided with a conductive core 13 and a conductive line disposed inside the coaxial inner periphery. The outer tube 14 is matched with the two poles 213 and 215 of the isolated input transformer circuit unit 21 and the two terminals 312 and 314 of the isolated output transformer circuit unit 31, so that the conductive core 13 and the conductive outer tube 14 become three phases. The transmission mode of a one-way circuit in the transmission circuit is also an innovative transmission line architecture type that has never been seen before, which can greatly improve the safety and reliability of the high-voltage transmission system and completely avoid the thunder. Damage and ensure that the relevant personnel have no electric shock.

As shown in FIG. 2, in the present example, the annular insulating portion 15 is in an annular space type, and the inside thereof is filled with an insulating gas 40; the insulating gas 40 may be, for example, nitrogen or hexafluoride. Inert gas such as sulfur, the positive gas pressure heat dissipation effect is the best, and the pressure sensing device can easily detect the abnormal state of the line.

Wherein, the inner wall of the conductive outer tube 14 is further combined with an insulating layer (such as sprayed insulating varnish, which is omitted from the drawing in this example).

As shown in Fig. 5, in the present embodiment, the annular insulating portion 15B is in the form of a solid insulating medium; the state disclosed in this example can be formed by using an insulating material such as plastic or rubber.

As shown in FIG. 3, in this example, the conductive core 13 and the conductive outer tube 14 of the unidirectional circuit of the current transmission cable 10 are formed by connecting a plurality of sections to each other so that the sections are formed. An insulating frame body 50 (such as ceramic) is disposed between the conductive core wire 13 and each of the conductive outer tubes 14 , wherein the insulating frame body 50 has a central through hole 51 and a limiting periphery 52 in a central configuration, wherein the center The through hole 51 is provided for the conductive core wire 13 to pass through, the limiting peripheral edge 52 is used for setting the end sleeve of the conductive outer tube 14 , and the ends of the conductive outer tubes 14 are provided with a relative abutting method. The flange 141 is provided with a plurality of locking holes 142 for locking by the locking member 143.

As shown in FIG. 4, in this example, the inner tube of the conductive outer tube 14 is provided with more than one core support seat 144 (such as ceramic), and the core support 144 is provided with a central hole 145 for the purpose. The conductive core wire 13 passes through the group limit.

The current transmission cable 10 is further provided with at least one magnetic force and electric field sensor (not shown) for sensing the configuration of the conductive core 13 and the conductive outer tube 14 The state, which is used to sense the point of failure. (Note: This example is more suitable for underground cable implementation)

Each of the fixed-pitch cables 10 is further provided with an elastic pulling device (not shown) for absorbing the expansion and contraction changes of the conductive core 13 to maintain the extended state thereof. The tightness is within a set range.

Wherein, the radial cross-sectional area of the tube wall of the conductive outer tube 14 is not less than one quarter of the radial cross-sectional area of the conductive core line 13.

Wherein, the conductive core wire 13 is selected from one of the conductive wire types of the aluminum wire combined steel wire, the copper wire, the copper wire combined steel wire or the aluminum wire combined steel wire; the conductive outer pipe 14 is a metal pipe (such as steel pipe, iron) Tube or aluminum tube, etc.; thus, it can be seen that the conductive outer tube 14 of the present invention can be used as a rigid and strong outer shell structure of the equal current transmission cable 10 in addition to being part of the power transmission circuit. The role of this, and the outer structure of the conventional coaxial cable is only purely different as the type and function of the insulating covering, which is also clearly distinguishable by the reader.

Advantages of the Invention: The "safe high-voltage electric transmission system and its equal current transmission cable" disclosed in the present invention makes the present invention conform to the conventional structure proposed in [Prior Art] by the above-mentioned innovative unique structural type and technical features. At least, the following advantages and practical advancement can be achieved: 1. Including the 345KV ultra-high voltage transmission system, if the technology of the present invention is used, there is no need to install a high-voltage electric tower, and the cost of the transmission system can be reduced to the current About 5% of the cost of knowing the construction cost is obviously a great leap forward and gospel of high-voltage electric transmission technology. 2. The application of the technology of the present invention can almost achieve zero electromagnetic wave radiation state, and there is no danger of electric shock. This part is also a major reform, even if the current current transmission cable is mis-digmed due to construction in the future, it can ensure relevant The personnel have no electric shock, so that residents around the transmission line can live in peace of mind without worrying about the danger of electric shock and electromagnetic waves. 3. The current transmission cable disclosed in the present invention can greatly reduce the loop inductance due to the use, so that the line voltage drop and the power loss can be reduced by at least half or more in the transmission and distribution effect, and can be completely eliminated. The problem of leakage of insulation obstruction, taking the length of 100-kilometer medium-range transmission as an example, the voltage drop can be reduced from at least 37% to 18.5%, and it can avoid the huge engineering of adding capacitors to compensate the voltage drop. Due to the dangers, energy consumption and cost increase caused by the installation of the capacitor, and the power transmission factor can be greatly improved. 4. The technology of the present invention can greatly improve the safety and reliability of the high voltage transmission system, including exempting the danger of using a helicopter to clean the hamper on the high voltage electric tower and completely avoiding the damage of the thunder. In addition, even when the current transmission cable is damaged by war or natural disasters, the damage rate can be greatly reduced. 5. Because of the advantages of greatly improved transmission power factor, improved substation that can increase transmission frequency and reduce transformer installation cost and space will become a specific target. For example, the industry can set a higher transmission frequency (such as 120HZ). The substation is used for the transmission system of the wind turbine, so that the cost and space of the transformer installation can be saved.

[Part of the Invention]

A‧‧‧Safe high-voltage electric transmission system

10‧‧‧current current transmission cable

11‧‧‧Power input

12‧‧‧Power output

13‧‧‧Conductive core wire

14‧‧‧Electrical outer tube

141‧‧‧Flange

142‧‧‧Lock hole

143‧‧‧Locking members

144‧‧‧core support

145‧‧‧ center hole

15‧‧‧Circular insulation

20‧‧‧Input transformer

21‧‧‧Isolated input transformer unit

213, 215‧ ‧ extreme

L1, L2‧‧‧ transmission direction

30‧‧‧Output transformer

31‧‧‧Isolated output transformer unit

312, 314‧‧ ‧ extreme

40‧‧‧Insulation gas

50‧‧‧Insulated frame

51‧‧‧ center hole

52‧‧‧ Limit margin

R1, R2‧‧‧ induced electromagnetic field direction

[Learn part]

80‧‧‧ Transmission lines

81, 81B‧‧‧ Current

82‧‧‧Induction electromagnetic field

83, 84‧‧‧Transformers

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic plan view of a preferred embodiment of the system of the present invention. Figure 2 is a cross-sectional view showing the structure of a preferred embodiment of the current transmission cable of the present invention. Figure 3 is an axial cross-sectional view showing a partial structure of a preferred embodiment of the current transmission cable of the present invention. Fig. 4 is a view showing an embodiment in which a core support is provided in the outer conductive tube of the present invention. Figure 5 is a cross-sectional view showing the structure of another preferred embodiment of the current transmission cable of the present invention. Fig. 6 is a view showing the direction of current transport and the state of magnetic lines of the current transmission cable of the present invention. Figure 7 is an explanatory diagram showing the inductive reactance of a conventional transmission line. Figure 8 is a simplified schematic diagram of an embodiment of a conventional high voltage electric tower transmission line.

Claims (16)

A safe high-voltage electric transmission system, comprising: a first-current current transmission cable, which is a linear extension type, including a power input end and a power supply output end, and the current transmission cable line separates a three-phase transmission circuit Forming three unidirectional loops, each of the unidirectional loops includes a conductive core wire and a conductive outer tube disposed in a coaxial inner periphery, and the conductive core wire and the conductive outer tube are spaced apart from each other to form an annular insulating portion And wherein the conductive core and the conductive outer tube have opposite transmission directions and the amount of the two currents is equal; an input transformer is electrically connected to the power input end of the current transmission cable. The input transformer comprises an isolated input transformer circuit unit having three phases, and the two extreme poles of the isolated input transformer circuit unit of the phase and the one-way loops of the current transmission cable are respectively The conductive core wire and the conductive outer tube are electrically connected; and an output transformer is electrically connected to the power supply output end of the current transmission cable, and the output transformer includes The phase-isolated output transformer circuit unit, the two extremes of the isolated output transformer circuit unit of the phase, and the conductive core wires and the conductive outer wires of the unidirectional circuits respectively provided by the current transmission cables The tube is electrically connected. The safe high-voltage electric transmission system according to claim 1, wherein the annular insulating portion is an annular space type, and an inert gas is filled inside, and an inner wall of the conductive outer tube is further combined. There is an insulating layer. The safe high-voltage electric transmission system according to claim 1, wherein the annular insulating portion is in the form of a solid insulating medium. The safe high-voltage electric transmission system according to the second or third aspect of the invention, wherein the conductive core wire and the conductive outer pipe of each of the one-way circuits of the transmission cable are formed by connecting a plurality of sections to each other. An insulating frame body is disposed between each of the conductive core wires and the conductive outer tubes of the plurality of sections, wherein the insulating frame body has a central through hole and a limiting periphery disposed in the same center, wherein the center through hole is used for The conductive core wire is disposed, the limiting periphery is used for setting the end portion of the conductive outer tube, and the end portions of the conductive outer tubes are respectively provided with opposing flanges, and the flange is provided with a plurality of flanges The locking holes are fixed by the locking member lock group. The safe high-voltage electric transmission system according to claim 4, wherein the inner tube of the conductive outer tube is provided with more than one core support seat, and the core support is provided with a central hole for the conductive The core wire is worn through the group limit. The safety high-voltage electric transmission system of claim 5, wherein the current transmission cable is further provided with at least one magnetic and electric field sensor for sensing the conductive core and the conductive outer tube. Configure the positive bit state between. The safety high-voltage electric transmission system of claim 6, wherein each of the fixed-current transmission cables is further provided with an elastic tensioning device for absorbing the expansion and contraction of the conductive core wire. Change to maintain the tightness of its extended state within a set range. The safe high-voltage electric transmission system according to claim 1, wherein the radial cross-sectional area of the conductive outer tube is not less than a quarter of a radial cross-sectional area of the conductive core. For example, the safe high-voltage electric transmission system described in claim 1 is characterized in that the conductive core wire is selected from the group consisting of aluminum wire combined with steel wire, copper wire, copper wire combined steel wire or aluminum wire combined steel wire. The conductive outer tube is made of a metal tube. An equal current transmission cable line is a linear extension type, comprising a power supply input end and a power supply output end, and the current transmission cable line is divided into three three-way transmission circuits into three unidirectional circuit types. Each of the unidirectional circuits includes a conductive core wire and a conductive outer tube disposed in a coaxial inner periphery, and the conductive core wire and the conductive outer tube are spaced apart from each other to form an annular insulating portion, and wherein the conductive core wire and The transmission directions of the conductive outer tubes are opposite to each other and the amounts of the two currents are equal. The current transmission cable according to claim 10, wherein the annular insulating portion is in an annular space type, and the inside is filled with an insulating gas, and the inner wall of the conductive outer tube is further combined. There is an insulating layer. The current transmission cable of claim 10, wherein the annular insulating portion is in the form of a solid insulating medium. The current transmission cable according to claim 11 or 12, wherein the conductive core wire and the conductive outer pipe of each of the one-way circuits are formed by connecting a plurality of segments to each other to make the conductive core wires of each segment. And an insulating frame body is disposed between each of the conductive outer tubes, wherein the insulating frame body has a central through hole and a limiting periphery disposed in the same center, wherein the center through hole is for the conductive core wire to pass through, The limiting periphery is used for setting the end portion of the conductive outer tube, and the end portions of the conductive outer tubes are provided with opposite flanges, and the flange is provided with a plurality of locking holes for It is fixed by the locking member lock set. The current transmission cable of claim 13, wherein the outer tube of the conductive outer tube has more than one core support seat, and the core support has a central hole for the conductive core. Wear group limit. The current transmission cable according to claim 10, 11 or 12, wherein the radial cross-sectional area of the conductive outer tube is not less than a quarter of the radial cross-sectional area of the conductive core. For example, the current transmission cable according to claim 10, wherein the conductive core wire is selected from the aluminum wire combined steel wire, the copper wire, the copper wire combined steel wire or the aluminum wire combined steel wire, or one of the conductive wire types. The conductive outer tube is made of a metal tube.