KR102768425B1 - Exchange method of porcelain bushing for termination connection box for power cable - Google Patents

Abstract

The present invention relates to a method for replacing a magnetic filament tube of a terminal junction box with a simplified replacement method. The method comprises sequentially performing the steps of dismantling an upper metal fitting, removing a magnetic filament tube, replacing a conductor sleeve, inserting a polymer filament tube, injecting insulating oil, and assembling an upper metal fitting tube, so that a conventional terminal junction box can be utilized to connect an overhead transmission line and an underground transmission line by only replacing an existing conductor sleeve with an extended conductor sleeve and replacing a conventional magnetic filament tube with a polymer filament tube.

Description

{EXCHANGE METHOD OF PORCELAIN BUSHING FOR TERMINATION CONNECTION BOX FOR POWER CABLE}

The present invention relates to a method for replacing a magnetic tube of a terminal junction box with a simplified replacement method. More specifically, in the process of replacing a magnetic tube surrounding a terminal junction box with a polymer tube, a conductor sleeve connected to a power cable is replaced with another conductor sleeve having an extended length, so that a terminal connection is possible only by replacing the polymer tube.

Typically, power cables are placed on towers to supply power to a desired location through underground, above ground, or under the sea using conductors that supply power.

The above power cables are connected by joint boxes at intervals of hundreds of meters or tens of kilometers, and the ends of the power cables are connected to overhead transmission lines by termination connection boxes.

The above termination boxes are classified into air termination boxes, gas termination boxes, and oil termination boxes depending on the state in which the exposed conductor ends at the ends of the power cables are connected.

Magnetic cabling, which is the most widely used cabling commercialized worldwide to cover terminal connections, is mostly used in transmission and distribution towers in Korea.

These magnetic tubes deteriorate and corrode due to various environmental and mechanical factors. The main causes are damage caused by long-term mechanical stress, lightning, and rapid temperature changes, which can even lead to damage to the terminal connection box. Therefore, as disclosed in Korean Patent Publication No. 10-2207794, a conventional diagnostic device and method capable of performing a pre-damage inspection of the magnetic tube have been developed.

In order to complement the problems of these magnetic or glass insulators, plastic insulators that can be applied to low-voltage overhead lines or lead-in lines have been developed and used recently. An example of this is the plastic core insulator described in Patent Publication No. 10-1150435.

However, there is a problem that only the magnetic tube cannot be replaced due to the size difference between the previously installed non-standard magnetic tube and the standard plastic tube, and the entire cable must be replaced.

Korean Patent Publication No. 10-2207794 Korean Patent Publication No. 10-1635669

The present invention was created to solve the problem that the process of replacing a plastic tube is complicated and immediate installation is difficult due to the difference in length between the conventional magnetic tube and the improved plastic tube as described above, and the purpose of the present invention is to provide a simple method of converting a non-standard magnetic tube into a standard plastic tube.

In order to achieve the above-described object, the method for replacing a magnetic tube of a terminal junction box with a simplified replacement method according to the present invention comprises: an upper metal fitting dismantling step of removing an upper metal fitting coupled to a magnetic tube in a direction away from the upper portion of the magnetic tube; a magnetic tube removal step of removing the magnetic tube by separating it from a power cable; a conductor sleeve replacement step of separating a first conductor sleeve installed at the end of the power cable and then installing a second conductor sleeve; a polymer tube inserting step of inserting a polymer tube so as to wrap around the circumference of the power cable; an insulating fluid injection step of injecting an insulating fluid into the interior of the polymer tube; and an upper metal fitting assembling step of assembling the upper metal fitting on the upper portion of the polymer tube.

In the above magnetic tube demolition step, after the insulating fluid filled in the inner space of the magnetic tube is removed, the magnetic tube can be removed.

The above second conductor sleeve may have an axial length of 650 mm or more and 700 mm or less.

The above conductor sleeve replacement step may include a first conductor sleeve removal step of separating the first conductor sleeve connected to the power cable from the power cable; and, after the first conductor sleeve removal step is performed, a second conductor sleeve installation step of connecting the second conductor sleeve to the power cable.

The above polymer tube may have an axial length of 1,970 mm or more and 2,030 mm or less.

The above polymer tube may have an axial length of 2,380 mm or more and 2,440 mm or less.

The above insulating fluid can be used at high temperatures and may use methylphenyl silicone oil with improved oxidation resistance and chemical resistance.

The above polymer tube may contain at least one of glass fiber, natural fiber, and synthetic fiber inside to enhance strength.

The above natural fibers may include at least one of cellulose fibers, protein fibers or mineral fibers.

The above synthetic fiber may include at least one of polypropylene fiber, nylon fiber, and polyvinyl alcohol fiber.

As described above, according to the method for replacing a magnetic tube of a terminal junction box with a simplified replacement method according to the present invention, the conventional terminal junction box can be utilized to connect an overhead transmission line and an underground transmission line by only replacing an existing conductor sleeve with an extended conductor sleeve and replacing a conventional magnetic tube with a polymer tube, thereby simplifying the replacement method and reducing construction costs.

Figure 1 is a photograph of multiple terminal connection boxes installed on a conventional steel tower.
Figure 2 is a photograph showing the damaged state in which the magnetic tube of a defective terminal block exploded and flew due to a failure.
Figure 3 is a photograph showing a normal terminal connection that was secondary damaged by debris flying from a damaged magnetic tube.
Figure 4 is a fractured perspective view showing a cross-section of a terminal connection box including a conventional non-standard magnetic field.
Figure 5 is an enlarged front view of a first conductor sleeve of a non-standard length installed in a conventional terminal connection box.
Figure 6 is a fractured perspective view showing a cross-section of a terminal connection box with an improved standard polymer tube installed.
Figure 7 is an enlarged front view of the second conductor sleeve replaced during the process of installing a standard polymer tube.
Figure 8 is a flow chart showing a method for replacing a magnetic tube of a terminal connection box with a simplified replacement method according to the present invention.
FIG. 9 is a graph showing the external electric field of a terminal junction box including a polymer tube by applying a magnetic tube replacement method of a terminal junction box with a simplified replacement method according to the present invention.
Figure 10 is a flow chart showing a method for replacing a magnetic tube of a terminal connection box with a simplified replacement method according to the present invention.

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

The present invention may have various modifications and embodiments, and specific embodiments are illustrated in the drawings and specifically described in the detailed description. This is not intended to limit the present invention to specific embodiments, but should be interpreted to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

In describing the present invention, the terms first, second, etc. may be used to describe various components, but the components may not be limited by the terms. The terms are only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The term "and/or" may include any combination of multiple related listed items or any one of multiple related listed items.

When a component is referred to as being "connected" or "connected" to another component, it can be understood that it may be directly connected or connected to that other component, but there may also be other components in between. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it can be understood that there are no other components in between.

The terminology used in this application is only used to describe specific embodiments and is not intended to limit the invention. Singular expressions may include plural expressions unless the context clearly indicates otherwise.

In this application, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, and can be understood as not excluding in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries, such as those defined in common dictionaries, may be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and may not be interpreted in an idealized or overly formal sense, unless explicitly defined in this application.

In addition, the following examples are provided to more completely explain to a person having average knowledge in the art, and the shapes and sizes of elements in the drawings may be exaggerated for a clearer explanation.

In high-voltage transmission systems, overhead transmission lines are installed on towers or underground transmission lines are laid out buried in the ground to transmit 154 kV high-voltage power, transporting the massive amounts of power supplied from power plants.

Accordingly, a plurality of terminal connectors are installed in the middle of the tower by a support frame to interconnect the wire terminals branched from the overhead transmission line and the wire terminals branched from the underground transmission line.

Referring to Fig. 1, support frames are installed at predetermined angular intervals along the perimeter of the tower, and a plurality of terminal connection boxes (1, 2) are installed on the outside of each of the support frames to connect the overhead transmission line and the underground transmission line.

However, referring to Fig. 2, in the case of a defective terminal connection box (1) to which a conventional magnetic tube is applied, the magnetic tube may be damaged by deterioration and corrosion due to various environmental or mechanical factors, and fragments of the damaged magnetic tube may scatter to the surroundings and damage other terminal connections or buildings.

Referring to Fig. 3, the scattered magnetic filament fragments can damage the magnetic filament included in the normal terminal connection box (2), and may cause damage to additional normal terminal connection boxes (2) in the future, so a replacement technology is required.

Referring to FIG. 4, a conventional terminal connection part includes a first conductor sleeve (10a) connected to the end of a power cable (3) inserted inside, a magnetic tube (20a) formed of a magnetic material to cover the outside of the power cable (3), a support part (30) connected to the lower end of the power cable (3) to support the entire structure, an insulating fluid (40) filled in the internal space of the magnetic tube (20a), and an upper metal part (50) covering an upper opening of the magnetic tube (20a).

The above magnetic shield (20a) covers the outside of the power cable (3) and is formed of a porcelain ceramic material with excellent insulating properties, thereby preventing leakage of high-voltage current flowing in the power cable (3).

The above support member (30) is configured to include a bottom bracket (31) that supports a terminal connection, a support insulator (34) that is connected at one end to the outer lower end of the bottom bracket (31) and at the other end to the support frame, a stress cone (32) that is mounted on the outer side of the insulation material of the power cable (3), an epoxy washer (33) that pressurizes the stress cone (32), and a lower copper tube (35) that is connected at the lower end of the bottom bracket (31) and covers the lower opening of the long-term magnetic insulator tube (20a).

The above insulating fluid (40) is filled in the internal space of the magnetic tube (20a), and the type of insulating fluid (40) may be an oil such as silicone oil having a high melting point or an insulating gas such as SF ₆ .

Referring to FIG. 5, the first conductor sleeve (10a) includes a first cable insertion portion (11a) on one side into which a conductor (3a) is inserted by removing a portion of the insulating material (3b) from the end of the power cable (3) and thus exposed, a first conductor insertion portion (12a) on the other side into which a separate conductor branched from an overhead transmission line is inserted at the top, and a first sleeve head (13a) connecting the first cable insertion portion (11a) and the first conductor insertion portion (12a).

The first cable insertion portion (11a) above has an empty hollow groove formed inside so that the conductor (3a) exposed at the end of the power cable (3) can be inserted.

The first conductor insertion portion (12a) above has an empty hollow groove formed inside to allow a conductor branched from an overhead transmission line located above the terminal connection portion to be inserted.

However, if fragments of the self-love object (20a) fly due to damage to the self-love object (20a), it may damage another self-love object (20a) in the vicinity.

Referring to FIG. 8, in order to solve the above-described problem, a method for replacing a magnetic tube of a terminal connection box with a simplified replacement method according to an embodiment of the present invention comprises an upper metal fitting dismantling step (S10) of removing an upper metal fitting (50) coupled to a magnetic tube (20a) in a direction away from the upper portion of the magnetic tube (20a), a magnetic tube removal step (S20) of separating and removing the magnetic tube (20a) from the power cable (3), a conductor sleeve replacement step (S30) of separating the first conductor sleeve (10a) installed at the end of the power cable (3) and then installing a second conductor sleeve (10b), a polymer tube insertion step (S40) of inserting a polymer tube (20b) to wrap around the circumference of the power cable (3), an insulating fluid injection step (S50) of injecting an insulating fluid (40) into the inside of the polymer tube (20b), and a step of inserting an insulating fluid (40) into the upper portion of the polymer tube (20b). It includes an upper metal fitting assembly step (S60) for assembling the upper metal fitting (50).

To explain in detail, in the upper metal fitting dismantling step (S10), the upper metal fitting (50) covering the upper part of the magnetic tube (20a) is separated from the magnetic tube (20a) and moved away from the upper part of the magnetic tube (20a).

In the above magnetic tube demolition step (S20), after the insulating fluid (40) filled in the inner space of the magnetic tube (20a) is removed, the magnetic tube (20a) is removed.

In the process of removing the above insulating fluid (40), an oil pump capable of transporting high viscosity fluid can be used, and a rotary pump, a gear pump, or a plunger pump can be used as the oil pump.

Since the above insulating fluid (40) may contain foreign substances or moisture, an additional filter may be applied.

The above conductor sleeve replacement step (S30) includes a first conductor sleeve removal step (S31) of separating the first conductor sleeve (10a) connected to the power cable (3) from the power cable (3), and a second conductor sleeve installation step (S32) of connecting the second conductor sleeve (10b) to the power cable (3) after the first conductor sleeve removal step (S31) is performed.

In the above first conductor sleeve removal step (S31), the power cable (3) inserted into the first conductor sleeve (10a) is moved away from the first conductor sleeve (10a) and separated from the first conductor sleeve (10a).

After the first conductor sleeve (10a) is removed, a second conductor sleeve installation step (S32) is performed in which the power cable (3) is inserted and connected to a second conductor sleeve (10b) whose axial length is longer than that of the first conductor sleeve (10a).

The above second conductor sleeve (10b) can be configured to have a length of 650 mm or more and 700 mm or less in the axial direction.

Since the length of the second conductor sleeve (10b) is 300 mm longer than the length of the first conductor sleeve (10a), the end is exposed outside the opening of the polymer tube (20b) so that the end of the wire branched from the overhead transmission line can be inserted.

In order to correspond to the second conductor sleeve (10b), the polymer tube (20b) has an axial length of 1,970 mm or more and 2,030 mm or less, thereby enabling compatibility between multiple terminal connection boxes and reducing costs through mass production.

In addition, in order to prevent flames generated from the outside from entering, the polymer tube (20b) is formed to have a length of 2,380 mm or more and 2,440 mm or less in the axial direction, thereby providing flame resistance to the polymer tube and enabling compatibility between multiple terminal connections.

The above insulating fluid (40) can be used at high temperatures and can use methylphenyl silicone oil with improved oxidation resistance and chemical resistance.

The above insulating fluid (40) may be used by including at least one of mineral oil, alkyl benzene, silicone oil, and alkyl naphthalene materials, and most preferably, silicone oil having excellent heat resistance may be used.

The above silicone oil may be used by including at least one of dimethyl silicone and methylphenyl silicone, and preferably, methylphenyl silicone with improved heat resistance that can be used at temperatures from -60°C to 200°C may be used.

The above polymer tube (20b) may include at least one of glass fiber, natural fiber, and synthetic fiber inside to strengthen the strength of the tube body so as to prevent it from being damaged by external impact.

The above natural fibers may include at least one of cellulose fibers, protein fibers, or mineral fibers, and most preferably, cellulose fibers that are environmentally friendly and easy to produce may be added.

The above synthetic fiber may include at least one of polypropylene fiber, nylon fiber, and polyvinyl alcohol fiber, and most preferably, polypropylene fiber having excellent voltage resistance and insulation properties may be used.

The terminal connection box including the polymer tube (20b) illustrated in Fig. 6 is identical to the conventional terminal connection box described with reference to Fig. 4, except for the second conductor sleeve (10b) and the polymer tube (20b).

Therefore, components that perform the same function as conventional terminal connections are given the same reference numerals and detailed descriptions are omitted.

Referring to FIG. 6, the replacement method of the magnetic tube of the terminal connection box with the simplified replacement method according to the present invention is applied to the terminal connection box including the polymer tube, and the terminal connection box includes a second conductor sleeve (10b) extended in the longitudinal direction and a polymer tube (20b).

Referring to FIG. 7, the second conductor sleeve (10b) includes a second cable insertion portion (11b) on one side into which a conductor (3a) is inserted by removing a portion of the insulating material (3b) from the end of the power cable (3) and thus exposed, a second conductor insertion portion (12b) on the other side into which a separate conductor branched from an overhead transmission line is inserted at the top, and a second sleeve head (13b) connecting the second cable insertion portion (11b) and the second conductor insertion portion (12b).

The second cable insertion portion (11b) above has an empty hollow groove formed inside so that the conductor (3a) exposed at the end of the power cable (3) can be inserted.

The second conductor insertion portion (12b) above has an empty hollow groove formed inside so that a conductor (13a) branched from an overhead transmission line located above the terminal connection portion can be inserted.

In Fig. 7, the length of the second cable insertion portion (11b) satisfies the requirement of 300 mm or more and 350 mm or less in the axial direction, and is extended by approximately 300 mm compared to the length of the first cable insertion portion (11a) exceeding 0 mm and 50 mm in the axial direction, thereby resolving the problem caused by the difference in length between the polymer tube (20b) and the magnetic tube (20a).

The terminal connection box including the polymer tube (20b) disclosed in Fig. 7 may be formed by extending the length of the second cable insertion portion (11b), but also extending the lengths of the second conductor insertion portion (12b) and the second sleeve head (13b).

Referring to FIG. 9, this is a graph showing the surface electric field outside the polymer tube (20b) when a lightning impulse test voltage of 1900 kV is applied to a terminal connection box including a polymer tube (20b) to which a magnetic tube replacement method of a terminal connection box with a simplified replacement method according to the present invention is applied.

To explain in detail, electrical devices such as terminal blocks must not only withstand constant voltage, but also be insulated against occasional lightning strikes or abnormal voltages during switching.

However, since it is cost-effective to provide insulation that can withstand any abnormal voltage without being damaged, the withstand voltage test voltage of electrical equipment over high voltage is standardized by the "test voltage standard," and the lightning impulse test voltage value (BIL, Basic Impuls Insulation Level) is disclosed in this standard.

When a lightning impulse test voltage of 1900 kV is applied, the external surface electric field of the pipe shall not exceed 2.5 kV. If the external surface electric field of the pipe exceeds 2.5 kV, discharge may occur along the external surface of the pipe, which may damage the terminal connection box.

Therefore, the polymer tube (20b) of the terminal connection box must satisfy the specified impulse design standard at the specified lightning impulse test voltage value.

Referring to Fig. 9, it can be confirmed that the equipotential lines are spaced narrowly at the bottom of the polymer tube (20b), so that the electric field is concentrated at the bottom of the polymer tube (20b).

On the other hand, it can be seen that the equipotential lines are spaced widely at the upper end of the polymer tube (20b) adjacent to the upper metal part (50), and thus the electric field is relatively smaller than at the lower end of the adjacent polymer tube (20b).

In the case of the lower part of the polymer tube (20b) where the above electric field is concentrated, the electric field value is 2.4 kV/mm, and in the case of the upper part of the polymer tube (20b), it is 0.21 kV. It can be confirmed that even when the polymer tube (20b) is applied, the surface electric field outside the tube satisfies the standard value.

Referring to FIG. 10, in order to help understand the method of replacing a magnetic tube of a simplified terminal connection box according to one embodiment of the present invention, a process can be performed by a field worker by explaining the method with reference to a photograph.

Therefore, even without replacing the entire conventional terminal junction box, the terminal junction box can be applied in the process of connecting overhead transmission lines and underground transmission lines by simply replacing internal components, such as conductor sleeves (10a, 10b) and conduits (20a, 20b), thereby reducing work time and cost.

Although the present invention has been described in detail through specific examples, this is only for the purpose of specifically explaining the present invention, and the present invention is not limited thereto, and it is obvious that the present invention can be modified or improved by a person having ordinary knowledge in the relevant field within the technical spirit of the present invention.

All simple modifications or changes of the present invention fall within the scope of the present invention, and the specific protection scope of the present invention will be made clear by the appended claims.

1: Defective termination connection
2: Normal terminal connection
3: Power cable
3a : Conductor
3b: Insulation
10a: 1st conductor sleeve
11a: 1st cable insertion part
12a: 1st conductor insertion part
13a: 1st sleeve head
10b: 2nd conductor sleeve
11b: 2nd cable insertion part
12b: 2nd conductor insertion part
13b: 2nd sleeve head
20a: Self-love
20b: Polymer Lover
30 : Support
31: Low-level bracket
32 : Stress cone
33: Foxy Washer
34 : Supporter
35: Lower East Wing
40 : Insulating fluid
50 : Upper bracket

Claims (1)

An upper part disassembly step for removing an upper part attached to a magnetic resonance imaging device in a direction away from the upper part of the magnetic resonance imaging device;
The magnetic tube removal step of separating and removing the magnetic tube from the power cable;
A conductor sleeve replacement step of separating the first conductor sleeve installed at the end of the above power cable and then installing the second conductor sleeve;
A polymer tube insertion step for inserting a polymer tube to wrap around the circumference of the above power cable;
An insulating fluid injection step for injecting an insulating fluid into the inside of the polymer tube; and
An upper fitting assembly step of assembling an upper fitting on the upper part of the above polymer tube;
Including,
In the above self-esteem demolition stage,
A method for replacing a magnetic tube in a terminal connection box, wherein the replacement method is simplified by removing the insulating fluid filled in the inner space of the magnetic tube, and then removing the magnetic tube.