WO2010120035A1 - Uninterruptible bypass method for an underground power line using an extension elbow having a split connection function - Google Patents

Abstract

The present invention relates to an uninterruptible bypass method for an underground power line, which enables uninterruptible maintenance for replacing of devices such as transformers, switches or the like, and cables of the underground power line. More particularly, the extension elbow of the present invention has a split connection function which enables the uninterruptible bypass of the underground power line, while conventional elbow connectors are only connectible to the ends of underground cables interconnecting switches and transformers of the underground power line. When the uninterruptible replacement of switches, transformers, and cables of the underground power line is performed when the extension elbow of the present invention is installed in lieu of conventional elbows for the new construction of an underground power line, or when conventional elbow connectors are uninterruptibly replaced in conventional underground power lines by extension elbows using a sequential separation and connection method, the extension elbow of the present invention enables the uninterruptible installation of bypass cables for temporary power transmission, and thus enables remarkably safe and quick uninterruptible installation. Further, the uninterruptible bypass method for the underground power line using the extension elbow having a split connection function according to the present invention is a novel and remarkably safe and economically advantageous underground wiring technique which enables the installation and construction of an underground power line to be conducted uninterruptibly during the daytime, as compared to conventional systems in which the installation and construction of an underground power line is mostly performed in an interrupted manner during nighttime, which is dangerous and inefficient.

Description

Uninterrupted bypass construction of underground distribution lines using extension elbows with branch connection

The present invention relates to an uninterrupted bypass construction for the overall underground distribution line, including the replacement of equipment and cables, such as transformers and switchgear of the underground distribution line, more specifically, the elbow coupled to the end of the cable for connecting the transformer or switch Due to its structure, bypass cannot be bypassed and underground cables cannot be cabled because of their characteristics (in the case of a processing line, the uninterrupted work is performed by connecting the bypass cable to the shelled area by covering the jacket). The extension elbow with branch connection function, which is designed to pass, has been applied during the new construction of underground distribution lines or in the case of existing underground lines, the existing elbow connection port is replaced with extension elbows by uninterrupted connection by sequential disconnection method None of the above underground distribution lines If a power outage is required, the extension elbow with branch connection, temporary transformer, switchgear, and bypass cable are used to bypass the underground distribution line for temporary transmission and then safely perform all operations on the distribution line in an uninterrupted state. It was made possible.

The underground process of Korea's overhead distribution line began in 1973 by relocating the electric poles along the main road to the back alley in the aspect of cable maintenance from Hyo Auto to Gwanghwamun, and supplying nearby customers from the column transformer using low voltage cables. It is planned and expanded as follows.

In 1961, Gyeongsung Electricity, Namsun Electricity, and Chosun Electricity were merged into a single electric power company, and the construction of 22kV underground distribution lines soared as the demand for electricity increased, reaching a total length of 40 km. As the load density in the downtown area increased rapidly, such as redevelopment and the enlargement of buildings, the underground business began in earnest.

In September 1975, the Seoul Metropolitan Government's four main gates of the main four major gates were held in Seoul from 1977 to 1981 through a meeting of executives from related departments under the direction of the president to overhaul the complex overhead lines (power lines and telephone lines) along the main four major roads in Seoul. Under the 32 km road, the underground project was in full swing, and the underground plan was prepared for the 1986 Asian Games and the 1988 Seoul Olympic Games. Since 1986, six regional metropolitan cities, including the central part of Seoul, have been selected and implemented.

Since the Seoul Olympics were successfully held in 1988, it has been actively developed in the name of supporting the national policy, and has recently been expanded to various areas such as new cities and industrial complexes.

 Since the need for underground business to improve the city's aesthetics has been continued, the underground business for overhead lines has continued, but it is difficult to carry out the business due to the problem of securing space equipment.

 Underground line business plans have been steadily increasing, so that the construction of overhead lines is technically impossible and difficult to maintain. To prepare for substations or expand the periphery of existing substations, facilities for power lines or distribution lines are installed to draw out distribution lines for multiple lines. Underground distribution lines for future load increases The target is the area near the substation drawer where the overhead line is concentrated, the place crossing the overpass, the highway, the railroad, etc. It is an area where administrative agencies and business cooperation are smooth.

In addition, as the city is developed and a new development complex is being built up, the proportion of the underground is gradually increasing. As the city plans to build construction and power lines under the ground, the project is carried out in consultation with the administrative departments. For example, Yeouido, Mokdong area, Jungmun tourism complex, Bomun complex, Sanggye, Relay, Gumi, Pyeongchon, Sanbon, Siheung district, etc. This is being applied.

Most of Korea's special high voltage underground power distribution system is composed of open loop system which can switch over to other systems at all times, and major customers adopt ALTS as a transfer switch by adopting main / reserve line (two lines) supply method. I use it. The spot network method with high supply channel and good circuit utilization was announced in some areas, including the Teheran-ro area in Gangnam, but was not implemented. In 1997, the three-line spot network method was applied to the third government complex of the Dunsan district in Daejeon. First, it is applied to the Blue House.

Until now, underground distribution lines have been mainly constructed in large urban areas with high loads, which raises concerns about power outages, and causes many obstacles in traffic and traffic caused by the grounding of switchgear and transformer. In addition, maintenance work of underground distribution lines is accompanied by power outages, so in areas with high power consumption, power outages are not possible during the day. .

The underground distribution line as described above is composed of a switch 100, 100 'and a transformer 110, 110' installed on the ground as shown in Figure 1 and 2, the switch 100 connected to the substation ( 100 ') and transformers 110 and 110' which are connected to the switchgear are connected to each other by a underground line in an annular network form, and are branched from the transformer to each customer or customer premises. will be.

* As described above, the switchgear 100, 100 'and the transformer 110, 110', which are connected by underground lines, have a ring-shaped shape, and power is supplied from both sides, so that even if one part is cut off, It is configured not to interfere.

In particular, the switchgear 100, 100 ′ and the transformer 110, 110 ′ are connected to each other by cables 120 and 120 ′ for constructing underground lines. An elbow connector 121 for engaging the connector bushings 101 and 111 of the switch 100, 100 ′ and the transformer 110, 110 ′ is provided at an end of the 120. As the 121 is inserted into and coupled to the connector bushings 101 and 111, the connection state between them is made.

The elbow connector 121 is to be formed by coupling the elbow connector 121 of the 'b' shape to the end of the underground cable 120, 120 'as shown in Figure 3, the elbow connector 121 On one side of the underground cable 120, 120 'is connected to the connecting rod 122 is in a state of being formed protruding, the connecting rod 122 is kept insulated from the elbow connector 121 The interconnection state is made by injecting the connecting rod 122 into the connector bushings 101 and 111 of the switch 100, 100 ′ or the transformer 110, 11 ′.

In addition, the underground line construction method by the underground cable 120, 120 'includes direct sales, pipelines, old fashioned methods, etc. The characteristics and application standards are as follows.

(1) direct sale

Power cables are directly buried in the ground, usually using troughs as cable protection, to protect the cables, and then cover and backfill them with sand. This method, however, involves road excavation when the cable is replaced, and is rarely used today.

-2 cable lines or less

-If line expansion is not expected in the future

-If the excavation is easy later

-Inevitable due to other conditions

(2) pipeline type

After pipes are constructed using pipes such as synthetic resin pipes, steel pipes, and fume pipes, cables are laid. Manholes are installed at both ends of the pipes at a certain distance to install and connect the cables. This method is mainly used because of the ease of maintenance.

-The number of cable lines is more than three lines less than nine lines

-If line expansion is expected in the future

If there is a road paving plan

-Direct sale is disadvantageous

(3) old fashioned

As a tunnel structure, such as a tunnel, the upper structure is a structure that can be laid on the inner wall side and allow workers to carry out maintenance work. Usually applies to the following cases.

-9 or more cable lines

-When split construction of pipes (8 holes or less) is impossible on both sides of the road

-Cable multi-line outgoing point of power generation and substation

-In case of difficulty in direct sales or pipeline

The underground low-voltage distribution line as described above is installed in close proximity to the pedestrians in the city downtown area and is directly connected to a safety accident when an abnormality occurs.

Currently, 70,9725 underground devices are installed, and underground cables amount to 36,61C-km. Underground cable line detection technology was introduced due to the occurrence of cable damage due to various excavation works such as road maintenance and water supply and sewage. In terms of the excavation, 16,192 cases were conducted annually, causing 45.4 damages in the case of high-voltage cables, and low-voltage cables have not been counted in detail.

The breaker operates when the high voltage cable is damaged, but in the case of low voltage cable, the breaker does not operate when the damage is minute, so there is a high possibility that the line leakage will continue. In 2001-2001 underground distribution line failure analysis and prevention measures published by KEPCO, approximately 82% of cases of failures by underground distribution facilities in 1997-2001 were caused by cables and connecting materials, which accounted for the majority of underground failures. According to the number of cases statistics, trauma accidents accounted for 39% and deterioration accidents accounted for 44%. On the other hand, in the breakdown of underground cables in KEPCO, the accident analysis data of cables and connecting materials accounted for about 40% of accidents and 60% of non-traumatic accidents. In the case of cable, natural deterioration is 42%, and the cause of accidents is high.

The underground distribution transformer uninterrupted replacement method using the elbow separation device, which KEPCO and two other companies have been designated as new power technologies, also poses this risk.

Looking at the disadvantages and risks of new power technology No. 47,

First, work is performed by installing the live switchgear of single or three phase elbow connector using pneumatic pressure. Because of the instantaneous impact on the bushing of the ground transformer, the live switchgear using) is highly likely to cause an accident due to impact, trauma or crack and damage to the bushing, cable and connecting material. As described above, the trauma causes the facility failure rate of the underground line to be the highest, and the technology of separating and connecting three phases at the same time may cause serious failure. In addition, by connecting the connection part for bypass cable connection, the cable is fixed and bypassed to maintain power. The connection part (junction, junction) is not only a conductor, but also a narrow part is forcibly attached to the device. Bushing damage and trauma to elbow joints can occur. In case of trauma to the cable connection such as the bushing of the device, the electric field is concentrated in the local area, which can cause arcing.In case of an arc caused by an expensive underground distribution transformer, it is very likely to lead to a large accident. It can be seen that. This also applies to three-phase live elbow separator.

Second, separate equipment for the installation of connection materials should always be accompanied.

The single phase elbow live switchgear has a small size and light weight, and the three phase simultaneous live elbow separation device used when working three phases at the same time is also small in volume, so it is a means for transporting separate equipment when moving for construction. There is also a risk of secondary accidents that occur during transportation. In addition, since the equipment must be installed in advance for construction and must be separated and dismantled after the completion of work, the disadvantage of requiring a lot of work time is not only followed. There is.

The present invention improves the problems as described above and expands the uninterruptible work range of underground distribution lines so that all operations are possible, and replaces the existing elbow fittings at the end of the cable for connecting the switch and the transformer for underground distribution lines. The extension elbow with branch design is designed to be applied to new construction of underground distribution lines, or in the case of existing underground lines, the existing elbow connections are replaced with extension elbows uninterrupted by the sequential disconnection method. In case of uninterrupted construction such as transformer, switchgear and cable replacement construction, by using the extension elbow having the above branch connection function, the bypass cable for temporary transmission is installed uninterrupted and the work section is switched to oblique state, making it very safe and fast. Construction can be done Of course, the underground distribution line using the extension elbow, which has a branch connection function, enables all work on the construction work during the uninterrupted state in the uninterrupted state. It is an object of the present invention to provide an uninterruptible bypass construction method.

The present invention for achieving the object as described above, the underground transformer and the switchgear for the underground distribution line connected by the existing elbow connector coupled to the end of the cable for underground lines because the power supply can be supplied from both sides In the switchgear and transformer, the cable of one side of the switchgear and the transformer is disconnected to be in a diagonal state, and the other cable is kept in a live state, and then the cable end of the wired state separated from the switch and the transformer is separated from the cable end. The existing elbow connector is removed and removed, and the extension elbow having the newly designed branch connection is coupled to the end of the cable from which the existing elbow connector is removed. Input cable to make cable in live state live and the other end in live state The cable is separated from the switchgear and the transformer so that it becomes oblique and replaces the existing elbow connector with an extension elbow having a branch connection function (all elbow connections, extension elbows, The insulation cap of the extension elbow uses the grounding tool to completely discharge the charged charge, and at the same time, the protective part and the protective device according to the safety rules for live work are used to protect the charging part and the worker protection measures. With ;;

If the switch and transformer on the underground distribution line and the cable connecting them are required to be replaced due to failure or aging, the end of the bypass cable having temporary switchgear and temporary transformer with the capacity corresponding to the section to be replaced should be After connecting the extension elbow coupled to the transformer, the cable of the section to be replaced is in a diagonal state, and then performs the replacement construction of the corresponding switch and transformer and the cable connecting them, and replaces the switch and transformer After the cable is connected to the live state is made, it is made by removing the temporary transmission bypass cable.

The present invention provides a very safe and quick replacement when devices and cables, such as switchgear or transformer for underground distribution lines, need to be replaced by extension elbows having branch connection functions capable of extension connection or additional bypass connection. The uninterrupted construction method of underground distribution lines, and if you want to perform the relevant construction necessary for the maintenance and repair of the underground distribution lines, the operation of most underground distribution lines in the past has been applied to the construction cost in the event of power failure in an unstable state at night. It is very reasonable because it can be efficiently and safely uninterrupted by weekly work, and it is economical technology with low construction cost as a whole even if uninterruptible products are applied to work sections.

1 is a configuration diagram of a typical underground distribution line

2 is a state diagram of a switch and a transformer in a typical underground distribution line

Figure 3 is an enlarged view showing the cable connection port of a typical underground distribution line

4 is an exploded cross-sectional view of the extension elbow according to the present invention.

5 is a process diagram for replacing the extension elbow according to the present invention to the switch connection portion

6 is a process diagram for replacing the extension elbow according to the present invention to the transformer connection portion

Figure 7 is a underground distribution line of the completion of the replacement of the extension elbow according to the present invention

Figure 8 is a cross-sectional view of the coupling portion made of the extension elbow according to the present invention

9 is a cross-sectional view of the insulating cap removed from the extension elbow of FIG.

FIG. 10 is a diagram illustrating a process of inserting a bypass cable for temporary transmission in the state of FIG.

FIG. 11 is a cross-sectional view of a temporary cable for temporary transmission connected in the state of FIG. 10; FIG.

Figure 12 is a construction example of the underground distribution line by the extension elbow according to the present invention

Figure 13 is another construction example of the underground distribution line by the extension elbow according to the present invention

Figure 14 is another construction example of the underground distribution line by the extension elbow according to the present invention

Figure 15 is another construction example of the underground distribution line by the extension elbow according to the present invention

Figure 16 is another construction example of the underground distribution line by the extension elbow according to the present invention

Explanation of symbols on the main parts of the drawings

10,10 ': Switchgear

20,20 ': transformer

30,30 ': Cable

40: extension elbow 41: connecting rod

42: branch connection pin 43: insulation cap

50: temporary switch

60: temporary transformer

70: bypass cable for temporary transmission 71: cable connection port

The terms or words used in this specification and claims are not to be construed as being limited to the common or dictionary meanings, and the inventors can appropriately define the concept of terms in order to explain their invention in the best way. Based on the principle, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is an exploded cross-sectional view of the extension elbow having the branch connection function according to the present invention.

In the extension elbow 40 according to the present invention, the ends of the cables 30 and 30 'are inserted and fixed inside the insulator, and the cables 30 and 30 are provided on both sides of the extension elbow 40. ') And the connecting rod 41 and the branch connection pin 42 in the energized state is connected to each.

At this time, the connecting rod 41 protrudes from one side of the extension elbow 40 and the branch connection pin 42 is inserted recessed from one side of the extension elbow 40.

In addition, while the connecting rod 41 is to be connected to the switch 10, 10 'or transformer 20, 20' for constructing the underground distribution line, the branch connection pin 42 Is to connect a work bypass cable to a separate temporary switch or transformer. One side of the extension elbow 40 corresponding to the branch connection pin 42 has a separate insulating cap 43 is coupled to the ground connection line as usual when the insulation cap 43 is in a coupled state as necessary When the switch 10, 10 'or the transformer 20, 20' needs to be replaced, the temporary switchgear may be removed by using the branch connection pin 43 in an open state after removing the insulation cap 43. The bypass cable can be connected by connecting a temporary transformer.

That is, as shown in FIG. 5, the existing elbow connector connected to the ends of the cables 30 and 30 ′ is connected to both sides of the switches 10 and 10 ′. In the case of replacing the extension elbow 40 of the present invention, one side of the cable 30, 30 'is separated to be in a diagonal state, and the other side of the cable is kept in a live state, as described above. After removing and removing the existing elbow connector, the new extension elbow 40 is replaced in the state where it is connected to the switchgear 10, 10 ′, and the diagonal cable is connected again to be live.

Therefore, the other side of the cable is also in a diagonal state, and when the existing elbow connection port is connected to the live state in the state of replacing the extension elbow, the switch 10, 10 'is continuously supplied with electric power without disconnection of the underground distribution line. Existing elbow connector can be replaced with extension elbow with branch connection.

In addition, even when the connection port of the transformer 20, 20 'is to be replaced, as shown in FIG. 6, one side cable of the transformer has a branch connection function in a state in which the elbow connection port is separated and then removed. It is necessary to replace with extension elbows, and the other cable can also be replaced with diagonally connected connectors.

Accordingly, as shown in FIG. 7, the switches 30, 10 ′ and the transformers 20, 20 ′ of all underground distribution lines are terminated with an extension elbow 40 having a new branch connection function. The connection state is maintained by 30 '.

Here, in the above illustration, only the state in which the switch 10, 10 'or the transformer 20, 20' is connected by the cables 30, 30 'in the form of an annular network is shown. Even if one side of the cable is changed to oblique state, the power distribution line is not disconnected. However, if the one-way one-way power supply is performed instead of the annular network connection, the above operation will not be performed. By using the switch 10, 10 'or transformer 20, 20' is to be made to replace the construction for the connection in the uninterrupted state.

As such, the underground distribution line where the replacement construction of the extension elbow having the branch connection function of the present invention with respect to the existing elbow connection port is to be completed due to the aging or failure of the switch, the transformer, and the cable, conventionally The work in the blackout condition has been going on for a long time, causing damage and complaints from power outages, expensive equipment and complicated facilities, and a lot of time and construction cost.

However, by using the extension elbow having a branch connection function according to the present invention and the bypass cable for temporary transmission, uninterruptible replacement construction can be easily and efficiently performed in a weekly operation, and the extension elbow having the branch connection function is It has a branch connection pin for convenient connection to connect the pass cable, so that the switch and transformer or cable can be replaced in an uninterruptible state.

That is, as shown in FIG. 8, each of the switches 10, 10 ′ and the transformers 20, 20 ′ is constructed with an underground line by extension elbows 40 having branch connections. It will be connected to 30 '.

Subsequently, when the switch 10, 10 ′ or the transformer 20, 20 ′ needs to be replaced, the insulation cap 43 is removed from the extension elbow 40 as illustrated in FIG. 9. Bypassing the cable connection port 71 at the end of a separate bypass cable 70 to the branch connection pin 43 exposed by removing the insulating cap 43, the bypass cable 70 The bypass 70 is connected to the temporary switchgear 50 or the temporary transformer 60 by-pass.

Hereinafter, the various uninterruptible replacement construction examples for the switchgear and transformer for underground distribution lines using the extension elbow having the branch connection function as described above.

* Construction example 1

When the uninterruptible replacement construction of the entire part of the underground distribution line is needed as shown in FIG. 12, when an uninterruptible replacement construction is performed on transformers located between adjacent switchgear, the extension connected to the switchgear. By connecting the bypass cable to the elbow and bypassing the underground distribution line so that it is in a live state, the elbow opening is disconnected from the transformer or switch of a neighboring transformer that supplies power to the transformer to be replaced. If the cable becomes oblique, the transformer will not be supplied with power.

At this time, the bypass cable is connected to the temporary transformer or more transformer to be replaced to ensure a stable power supply to each customer or customer premises.

As a result, the transformer to be replaced becomes oblique by sequential disconnection operation. Therefore, the safe transformer and the quick replacement of the transformer are performed. In this process, the temporary transformer is continuously powered by the live bypass cable. As a result, it can be maintained uninterrupted in the customer or customer premises.

In addition, when the replacement construction of the transformer is made as described above, when the replacement cable in the diagonal state is connected to the live state, power is supplied to the existing underground distribution line while power is supplied to the replaced transformer as described above. After the separation of the bypass cable, an uninterruptible replacement construction for the transformer is made.

The uninterruptible replacement construction of such a transformer is applied to all cases in which a plurality of transformers are replaced at the same time or a single transformer is to be replaced alone.

* Construction example 2

As shown in FIG. 12, when a total uninterruptible replacement construction is required for some sections including a switch and a transformer in an underground distribution line, a branch connection function connected to a switch and a transformer adjacent to a transformer adjacent to the switch to be replaced is required. With the bypass cable connecting the temporary switchgear and the temporary transformer connected to the extension elbow, the power supply is continued with the bypass cable, and the underground cable within the replacement section is disconnected from the neighboring transformer and the switchgear to be in a diagonal state. Make. Therefore, after carrying out the replacement construction of the underground cable, switchgear and transformer in the diagonal state, supply power to the underground distribution line where the replacement work is performed and remove the bypass cable that is temporarily supplied to remove the bypass cable. Uninterruptible replacement construction will be made.

* Construction Example 3

When replacing the switch with one-way one-way power supply, the extension elbow having the branch connection function of the switch to replace the bypass cable having a temporary switch having a capacity equal to or higher than that of the switch as shown in FIG. The transformer is connected to the switch to be replaced, and the transformer is connected to the temporary switch to bypass the power supply.

In such a state, the cable connecting the switch and the transformer is separated from the neighboring transformer and the switch to be in a diagonal state, and then, when the live cable is disconnected from the switch, the power supply to the switch to be replaced is cut off, thereby ensuring a safe replacement. It is possible, and because the power is continuously supplied to each customer and customer premises through a transformer bypassed from the temporary switchgear, the switchgear in the uninterrupted state is made.

* Construction example 4

When the switch is supplied in the annular network form by the two sides of the cable when the replacement of the cable connected to the switch to be replaced as shown in Fig. 14 is to be in a diagonal state is to replace the switch safely, The transformer in the state connected to the switch to be replaced is still in the state of the power supply in the form of an annular network from the switch, so even if the power supply to the switch is cut off, the power supply to each customer and customer premises is made smoothly. As a result, a safe switch replacement in an uninterruptible state is also made.

* Construction example 5

In the underground distribution line where one-way one-way power supply is performed, when replacement construction is needed for another transformer located between the switch and the transformer, the bypass cable is connected to one switch and the neighboring transformer as shown in FIG. 15. In case of connecting elbow to each other, connect the temporary transformer with the same capacity or higher to continue the power supply, and remove the cable connected to the transformer to be replaced from the neighboring transformer or switch and then in the diagonal state After completing the safe replacement construction, by connecting the cable connected to the replaced transformer to supply power to the completed line and at the same time separate and remove the temporary bypass cable is a safe transformer replacement in the uninterrupted state.

* Construction Example 6

When it is necessary to replace and replace another transformer located between the switch and the transformer among the transformers having an annular distribution state in which power is supplied by both cables, one end of the bypass cable is connected to one switch as shown in FIG. Or connected to an extension elbow formed on one transformer, connecting a temporary transformer with a capacity equal to or higher than the corresponding transformer, and disconnecting the cable connected to the transformer to be replaced from a neighboring transformer or switch, in the diagonal state. If the bypass cable is removed after supplying power to the cable connected to the replaced transformer, a safe transformer replacement in an uninterruptible state is also performed.

Various construction examples as described above will vary depending on whether the switchgear and the transformer are receiving one-way power supply or power is supplied from both sides through the loop-type underground distribution line. Depending on the location of the cable and the shape of the section, it may be applied differently.

Claims (11)

1. In the switchgear and transformer of the underground distribution line connected by the existing elbow connector coupled to the end of the cable for the underground distribution line, the cable for the electric power supply is separated to be in a diagonal state while the switch and the transformer are uninterrupted. After that, the existing elbow connector is separated and removed from the end of the oblique cable, and the extension elbow having the branch connection function is coupled to the end of the cable from which the existing elbow connector is removed. The extension elbow replacement process of replacing all the existing elbow fittings for the switch and the transformer installed in the underground distribution line with the extension elbow by repeating the connection of the cable in the live state.

   If switchgear and transformer on underground distribution line and cables connecting them are required to be replaced due to failure or aging, the end of bypass cable for temporary transmission is connected to extension elbows connected to switchgear and transformer outside the section. After connecting the temporary switchgear and the temporary transformer more than the capacity of the section to be replaced, so that the power supply is continued, the switchgear, transformer and cable of the section to be replaced are separated in a diagonal state, and then Perform the replacement construction of the transformer and the cables connecting them, and connected to supply the power to the switch and the transformer and underground distribution cable, and then by removing and removing the bypass cable installed for the temporary transmission Extension elbow with branch connection function Uninterrupted bypass construction method for underground distribution lines.
2. The method of claim 1,

   The extension elbow allows the cable to construct the underground line to be electrically connected to the connecting rod protruding to one side of the extension elbow made of an insulator, and the branched connection connected to the cable and connecting rod to the other side of the extension elbow. Allow pins to form,

   The branch connection pin is recessed in the inner side of the extension elbow, which is an insulator, and the extension elbow having the branch connection function is formed by combining a separate insulating cap detachable to the extension elbow in which the branch connection pin is located. Uninterrupted bypass construction method for underground distribution lines.
3. The method of claim 1,

   In the extension elbow replacement process, when the switch and the transformer have a ring-shaped connection structure in which power is supplied by the cables on both sides, one cable is oblique and the other cable is kept live. By performing the replacement work for the cable in the oblique state, and then changing the connection port for the other cable by changing the oblique line and the live state, the uninterrupted replacement construction of the connector for the switch and the transformer is made. Uninterrupted bypass construction method of underground distribution line using an extension elbow having a branch connection.
4. The method of claim 1,

   In the extension elbow replacement process, when the switch and the transformer have a one-way connection structure in which power is supplied by one cable, the bypass cable is connected to the switch and transformer to which the connector is to be replaced. Extension cable with branch connection function, so that bypass cable becomes live state and cable to replace connector becomes oblique state so that connection construction in case of uninterruption of the switch and transformer is performed. Uninterrupted bypass construction of underground distribution lines using elbows.
5. The method of claim 1,

   When the transformer in the section between the adjacent switch and the switch is to be replaced, the bypass cable for temporary transmission is connected to the extension elbow of the switch so that the bypass cable becomes live and the cable of the transformer to be replaced. The uninterrupted bypass construction method of underground distribution lines using an extension elbow having a branch connection function, so that the uninterrupted construction of the transformer is performed in a diagonal state.
6. The method of claim 1,

   When installing the section of underground distribution line including switchgear and transformer, connect bypass cable for temporary transmission to separate switch and transformer extension elbow adjacent to switchgear and transformer to be replaced and make live An uninterruptible bypass construction method for underground distribution lines using an extension elbow having a branch connection function, in which a cable of a switch and a transformer to be replaced is in a diagonal state so that a safe switch and an uninterruptible section of the transformer are replaced.
7. The method of claim 1,

   When replacing the switch of the underground distribution line where one-way electric power is supplied by one cable, a bypass cable for temporary transmission having a temporary switch is connected to the extension elbow of the live cable connected to the switch to be replaced, and the temporary switch An extension having a branch connection function characterized in that the bypass connection to the transformer connected from the switch to be replaced is bypassed, so that the cable between the switch and the transformer to be replaced can be in a diagonal state so that a safe uninterruptible replacement construction of the switch can be made. Uninterrupted bypass construction of underground distribution lines using elbows.
8. The method of claim 1,

   When the switch in the annular distribution state where the switch and the transformer are powered by the cables on both sides is to be replaced, only the corresponding switch is in a state where the live cable connected to the switch to be replaced becomes oblique. An uninterruptible bypass construction method for underground distribution lines using extension elbows with a branch connection function, which allows the switch and transformer to maintain an annular connection structure as the diagonal cable becomes live after being replaced with a switch.
9. The method of claim 1,

   When replacing a transformer, connect the bypass cable for live transmission with the temporary transformer to the extension elbow of the live cable connected to the transformer to be replaced, and connect the bypass cable live, and replace the separated cable from the live cable. The uninterruptible bypass construction method of the underground distribution line using an extension elbow having a branch connection function, characterized in that the cable of the transformer to be separated to be in a diagonal state to perform a safe uninterrupted replacement construction of the transformer.
10. The method of claim 9,

    When replacing the transformer located between the switch and the transformer among the one-way one-way power supply, the extension elbow of the transformer located on both sides of the transformer to replace the bypass cable for temporary transmission with the temporary transformer. After connecting to the live state by connecting to the cable, the cable of the transformer to be replaced to be disconnected to the diagonal state to use the extension elbow having a branch connection function characterized in that the safe uninterrupted replacement construction for the transformer Uninterrupted bypass construction for underground distribution lines.
11. The method of claim 9,

    When replacing the transformer located between the switch and the transformer in an annular distribution state where the power is supplied to the transformer by both cables, for temporary transmission having a temporary transformer at one of the connection elbows of the transformer. After connecting the bypass cable in a live state, the other cable is disconnected in a diagonal state so that an uninterrupted safety installation of the transformer can be performed by using an extension elbow having a branch connection function. Uninterrupted bypass construction method for underground distribution lines.

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