Cable duct for transformers

Abstract

To provide a cable duct for transformers capable of easily performing attaching work of a cable for temporary supply of a transformer, attaching and detaching work of a power cable, etc.SOLUTION: A cable duct for transformers comprises a main circuit conductor 6, which is provided from a horizontal part 4 to a vertical part 5 of a cable duct 1, and a branch conductor 7 which is connected to the main circuit conductor 6 and to which a connection conductor 8 for connecting a cable 9 is connectable. The branch conductor 7 is stored in the vertical part 5 and a first branch space 18a and a second branch space 18b, which are branched by a partition wall 13, are formed lower than the branch conductor 7 in the vertical part 5. A first opening 31 facing the first branch space 18a and a second opening 32 facing the second branch space 18b are provided in the vertical part 5, such that the cable pulled into the branch spaces 18a and 18b is connectable to the branch conductor 7 via the connection conductor 8.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cable duct for a transformer provided on the secondary side of a transformer, in which a power cable and a temporary supply cable or a replacement power cable can be installed.

Background Art

[0002] As a cable duct for a transformer, the applicant has previously proposed the configurations shown in Patent Documents 1 and 2 below.

[0003] The former cable duct includes a first opening for working to connect an external cable to a power cable. An extension duct is provided on the outer surface of the cable duct so as to cover the first opening, and a second opening is formed in the extension duct. The connection work between the connection member that is connected to the power cable and protrudes outside from the first opening and the external cable can be performed through the second opening. Further, a disconnection and connection part for disconnecting and connecting the conduction between the main circuit conductor that supplies the power of the transformer in the cable duct to the load side and the power cable is provided at the upper part of the duct, and an opening through which this disconnection and connection part can be operated from the outside is provided on the upper surface of the cable duct.

[0004] The latter cable duct is provided with a removable insulating plate below the connection end of the lead wire from the transformer in the cable duct, and a working space for performing work is provided below the insulating plate. This insulating plate is attached by bolts or the like to attachment members such as angle members, arm members, or adhesive tapes fixed inside the duct, and after removal, it is taken out and stored outside the cable duct.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the former configuration, since the extension duct is provided so as to cover the first opening of the cable duct, when work inside the cable duct is required, it is necessary to insert a hand through the second opening of the extension duct and further insert a hand into the first opening, making the work difficult. Moreover, if the opening is narrow, the work cannot be carried out, so there is a disadvantage that the extension duct has to be removed.

[0007] Also, in the latter configuration, it is not intended to be able to connect a temporary supply cable or a replacement power cable in addition to the power cable so as to facilitate cable switching. Moreover, the insulating plate is always housed inside the cable duct and does not simply and immediately shield the space between the charging part when needed. Therefore, it takes time to attach and detach the insulating plate, resulting in poor work efficiency. Also, when the insulating plate is not in use, it is necessary to take out the insulating plate outside the cable duct, so there is a risk of loss.

[0008] The present invention has been made in view of such circumstances, and the main problem is to provide a cable duct for a transformer that can easily perform the attachment work of the temporary supply cable of the transformer, the attachment and detachment work of the power cable, etc.

[0009] Another problem is to provide a cable duct for a transformer that can always house an insulating plate for shielding the space between the charging part inside the duct and can easily install and remove the insulating plate.

Means for Solving the Problems

[0010] In order to achieve the above problems, the cable duct for a transformer according to the present invention is a cable duct for a transformer having a horizontal part provided above the transformer and a vertical part extending downward from this horizontal part, A main circuit conductor that is connected to the bushing of the transformer and provided from the horizontal portion to the vertical portion, and a branch conductor that is connected to the main circuit conductor and to which a connection conductor for connecting a cable can be connected. The branch conductor is housed in the vertical portion, and below the branch conductor in the vertical portion, a first branch space and a second branch space branched by a partition wall are formed. In the vertical portion, a first opening facing the first branch space and a second opening facing the second branch space are respectively provided. The cable drawn into each of the branch spaces can be connected to the branch conductor via the connection conductor.

[0011] Therefore, normally, a power cable is drawn into one of the branch spaces, for example, the first branch space, and connected to the branch conductor via a connection conductor for use. When temporarily supplying power from the transformer when replacing or repairing the cable from this state, the operation of removing the connection conductor connecting the power cable disposed in the first branch space is performed through the first opening facing the first branch space. Thereafter, the operation of drawing a temporary supply cable into the second branch space and connecting it to the branch conductor via the connection conductor is performed through the third opening facing the second branch space.

[0012] When replacing or repairing the power cable without performing temporary supply, the operation of drawing a power cable into the unused second branch space and connecting it to the branch conductor via the connection conductor is performed through the second opening facing the second branch space. Thereafter, through the first opening, the connection conductor connecting the power cable disposed in the first branch space is removed, and this power cable is removed.

[0013] Therefore, it is possible to perform cable switching operations using the empty branch space, so that the work efficiency can be improved.

[0014] Further, a connection / disconnection part for connecting and disconnecting the main circuit conductor and the branch conductor may be provided in a part accommodated in the vertical part of the main circuit conductor, and a third opening through which this connection / disconnection part can be operated from the outside may be further provided in the vertical part.

[0015] In such a configuration, since the operation of connecting and disconnecting the main circuit conductor can be performed through the third opening provided in the vertical part of the cable duct, the operation can be easily performed.

[0016] Note that the insulating plate for shielding between the charging part is preferably always accommodated in the cable duct and shields the front of the charging part as needed.

[0017] Therefore, a rotary insulating mechanism for shielding between the branch conductor and the connection conductor when the connection conductor for connecting the cable is not connected to the branch conductor may be provided in each branch space.

[0018] As the rotary shielding mechanism, for example, an insulating plate that can be rotated between a position where the upper end part of the branch space is in an open state and a position where it is in a closed state, and a swing piece swingably provided at the tip of the insulating plate are provided, and the swing piece may be magnetized to the partition wall or the vertical part of the cable duct.

[0019] With such a configuration, since the insulating plate can be held by magnetizing the swing piece to the partition wall or the vertical part of the cable duct at a position where the upper end part of the branch space is in an open state or a closed state, complicated work for attaching and detaching the insulating plate is not required, and the working time can be shortened.

[0020] Further, a slide-type insulating mechanism for shielding between the main circuit conductor and the branch conductor may be provided above the branch conductor in the vertical part of the cable duct when the conduction between the main circuit conductor and the branch conductor is blocked by the connection / disconnection part (by removing the connection / disconnection part). As a slide-type insulation mechanism, for example, an insulating plate that can slide between a position where the main circuit conductor and the branch conductor are in an open state and a position where they are in a closed state, and a flange portion fixed to the tip of this insulating plate are provided, and the flange portion may be made magnetizable to the vertical portion of the cable duct.

[0021] With such a configuration, the position where the insulating plate is slid to open the space between the main circuit conductor and the branch conductor or to close it is held by magnetizing the flange portion to the vertical portion of the cable duct. Thus, complicated work for attaching and detaching the insulating plate becomes unnecessary, and the working time can be shortened.

Advantages of the Invention

[0022] As described above, according to the present invention, the work of attaching the temporary supply cable to the transformer, the work of attaching and detaching the power cable, etc. can be easily performed.

[0023] In addition, since a mechanism is provided to rotate or slide the insulating plate inside the cable duct to insulate from the charging portion and hold that state, the installation and removal work of the insulating plate can be easily performed, and the insulating plate can be always stored inside the cable duct, so there is no risk of loss.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0026] FIG. 1 is a cross-sectional view showing a configuration example of a cable duct 1 for a transformer (hereinafter referred to as a cable duct) according to an embodiment of the present invention.

[0027] The transformer 2 steps down high-voltage power to a predetermined voltage (22 kV or 6 kV), and a bushing 3, which is an output terminal provided on the secondary side, is provided on the upper part.

[0028] The cable duct 1 includes a horizontal portion 4 having a duct shape with a substantially rectangular cross-section that extends substantially horizontally above the transformer 2, and a vertical portion 5 having a duct shape with a substantially rectangular cross-section that extends downward from the horizontal portion 4 at a substantially right angle. Inside, there are a main circuit conductor 6 connected to the bushing 3 of the transformer 2 to transmit output power, a branch conductor 7 connected to the end of the main circuit conductor 6, and a connection conductor 8 having one end connected to the branch conductor 7 and the other end connectable to a pressure contact terminal 10 of a cable 9.

[0029] The vertical portion 5 of the cable duct includes a narrow-width portion 5a with a narrow width and a wide-width widened portion 5b formed below it.

[0030] The main circuit conductor 6, the branch conductor 7, and the connection conductor 8 are each constituted by a conductor plate having a predetermined thickness and width, and are connected by bolting the respective conductor plates.

[0031] The main circuit conductor 6 is provided from the horizontal portion 4 to the vertical portion 5 of the cable duct 1, and is fixed to a plurality of insulators 11 fixed to the narrow portions 5a of the horizontal portion 4 and the vertical portion 5 of the cable duct 1, and is held in a state of being insulated from the cable duct 1. This main circuit conductor 6 is composed of a horizontal conductor 6a fixed within the horizontal portion 4, a vertical conductor 6b fixed within the narrow portion 5a of the vertical portion 5, and a disconnecting and connecting portion 6c detachably fixed to the lower end of the vertical conductor 6b, enabling the main circuit conductor 6 to be disconnected and connected to the branch conductor 7. Therefore, the disconnecting and connecting portion 6c, which forms a part of the main circuit conductor 6, is detachably provided at the end portion of the main circuit conductor 6, that is, the end portion connected to the branch conductor 7.

[0032] In the central part inside the widened portion 5b, a partition wall 13 fixed to the foundation 12 with anchor bolts is erected so that a gap is formed between the upper end of the widened portion 5b. This partition wall 13 is composed of an erected portion 13a provided on the extension line of the vertical conductor 6b of the main circuit conductor 6, a top plate 13b horizontally fixed to the upper end portion of this erected portion 13a, and flange portions 13c bent downward at both side edges of this top plate 13b.

[0033] The branch conductor 7 is disposed with a gap between the upper wall 15 of the widened portion 5b and the top plate 13b of the partition wall 13 in the middle of the vertical portion 5 of the cable duct 1, that is, in the upper part inside the widened portion 5b. This branch conductor 7 extends substantially perpendicular (in the left - right direction of the paper surface) with respect to the erected portion 13a of the partition wall 13, and is fixed to a plurality of insulators 16 fixed to the partition wall 13 (top plate 13b), and is held in a state of being insulated from the partition wall 13.

[0034] Therefore, below the branch conductor 7, a first branch space 18a and a second branch space 18b branched by the partition wall 13 are formed, and both end portions of the branch conductor 7 are disposed so as to face the upper - end openings of the branch spaces 18a and 18b.

[0035] The connection conductor 8 has its upper end detachably connected to both ends of the branch conductor 7. When it is connected to the branch conductor 7, it is fixed to the insulator 17 fixed to the partition wall 13 (flange portion 13c) and is held in a state insulated from the partition wall 13. Here, let the connection conductor on the first branch space side be 8a and the connection conductor on the second branch space side be 8b. Therefore, when the connection conductors 8a and 8b are attached to the branch conductor 7, the lower ends of the connection conductors 8a and 8b are arranged in the middle of the corresponding branch spaces 18a and 18b.

[0036] In each of the branch spaces 18a and 18b, cables (power cable 9, temporary supply cable, etc.) can be drawn in through the cable drawing passages 12a and 12b provided in the base 12 or through a cable insertion portion (not shown) provided at the lower part of the vertical portion 5. The drawn-in cable connects the pressure contact terminals provided at its end to the lower end of the connection conductor 8, and can be electrically connected to the branch conductor 7 through this connection conductor 8.

[0037] Also, in each of the branch spaces 18a and 18b, a cable support member 19 is detachably fixed to the partition wall 13 so that the drawn-in cable can be positioned and supported.

[0038] Furthermore, inside the vertical portion 5, insulation mechanisms 21, 22, and 23 for shielding from the charging portion are housed. In this example, the insulation mechanisms include a first insulation mechanism 21 provided below the branch conductor 7 in the first branch space 18a and capable of shielding the charging portion including the branch conductor 7 from below, a second insulation mechanism 22 provided below the branch conductor 7 in the second branch space 18b and capable of shielding the charging portion including the branch conductor 7 from below, and a third insulation mechanism 23 for shielding the main circuit conductor 6 (vertical conductor 6b) from below when the disconnection and connection portion 6c is removed above the branch conductor 7.

[0039] The first insulation mechanism 21 and the second insulation mechanism 22 have the same configuration and are symmetric with respect to the standing portion 13a of the partition wall 13. That is, the first insulating mechanism 21 has a rotary shaft 21a rotatably supported along the lower edge of a flange portion 13c facing the first branch space 18a of the partition wall 13. By rotating an insulating plate 21b about this rotary shaft 21a, the tip of the insulating plate 21b can be displaced from a position where it contacts or is close to the inner surface of the vertical portion 5 of the cable duct 1 to a position where it contacts or is close to the standing portion 13a of the partition wall 13. A swing piece 21e having a magnet 21d provided on one side thereof via a rotating portion 21c parallel to the rotary shaft 21a is swingably provided at the tip of this insulating plate 21b. The swing piece 21e is rotated so that the magnet 21d faces the inner surface of the cable duct 1 when the tip of the insulating plate 21b contacts or is close to the inner surface of the cable duct 1, and is also rotated so that the magnet 21d faces the standing portion 13a of the partition wall 13 when the tip of the insulating plate 21b contacts or is close to the standing portion 13a of the partition wall 13.

[0040] Similarly, the second insulating mechanism 22 has a rotary shaft 22a rotatably supported along the lower edge of a flange portion 13c facing the second branch space 18b of the partition wall 13. By rotating an insulating plate 22b about this rotary shaft 22a, the tip of the insulating plate 22b can be displaced from a position where it contacts or is close to the inner surface of the vertical portion 5 of the cable duct 1 to a position where it contacts or is close to the standing portion 13a of the partition wall 13. A swing piece 22e having a magnet 22d provided on one side thereof via a rotating portion 22c parallel to the rotary shaft 22a is swingably provided at the tip of this insulating plate 22b. The swing piece 22e is rotated so that the magnet 22d faces the inner surface of the cable duct 1 when the tip of the insulating plate 22b contacts or is close to the inner surface of the cable duct 1, and is also rotated so that the magnet 22d faces the standing portion 13a of the partition wall 13 when the tip of the insulating plate 22b contacts or is close to the standing portion 13a of the partition wall 13.

[0041] The third insulating mechanism 23 includes a housing portion 24 formed by a double wall that is open toward the inside of the narrow portion 5a on a part of the horizontal wall portion that transitions from the narrow portion 5a to the widened portion 5b of the upper wall 15 of the widened portion 5b of the vertical portion 5. A slide-type insulating plate 23a that is displaceable in a direction to close the lower end of the narrow portion 5a is housed inside the housing portion 24. A flange portion 23b erected upward is fixed to an end portion of the insulating plate 23a facing the narrow portion 5a, and magnets 23c that can be magnetized to the inner surface of the narrow portion 5a are fixed to both side surfaces of the flange portion 23b.

[0042] Therefore, when the insulating plate 23a is housed in the housing portion 24, the flange portion 23b is magnetically attached to the inner wall of the narrow portion 5a close to the housing portion 24 by the magnets 23c, and the state in which the insulating plate 23a is housed is maintained. Also, when the connection / disconnection portion 6c of the main circuit conductor 6 is removed and the insulating plate 23a is displaced to a position closing the narrow portion 5a, the flange portion 23b is magnetically attached to the inner wall of the narrow portion 5a far from the housing portion 24 by the magnets 23c, and the state of closing the narrow portion 5a is maintained.

[0043] Also, a first opening 31 that can be opened and closed by a first opening / closing lid 31a is provided on the side surface of the vertical portion 5 facing the first branch space 18a, and a second opening 32 that can be opened and closed by a second opening / closing lid 32a is provided on the side surface of the vertical portion 5 facing the second branch space 18b. Through these openings (the first opening 31 and the second opening 32), operations such as connecting and disconnecting the cables drawn into the branch spaces 18a and 18b to / from the branch conductor 7 via the connection conductor 8 are possible.

[0044] Also, a third opening 33 for performing operations such as removal and attachment of the connection / disconnection portion 6c of the main circuit conductor 6 is provided on the side surface of the narrow portion 5a of the vertical portion 5, that is, on the portion before transitioning to the widened portion 5b (the side surface of the narrow portion 5a directly above the widened portion 5b). The third opening 33 can also be opened and closed by a third opening / closing lid 33a.

[0045] In the above configuration, under normal conditions, as shown in FIG. 1, the power cable 9 is drawn into the first branch space 18a. This power cable 9 is connected to the branch conductor 7 via the connection conductor 8a and is electrically connected to the transformer 2 via the main circuit conductor 6. In this state, the rotating insulating plate 21b provided in the first branch space 18a has its tip portion close to the partition wall 13 and the swinging piece 21e magnetically attached to the partition wall 13. The rotating insulating plate 22b provided in the second branch space 18b has its tip portion close to the inner surface of the widened portion 5b and the swinging piece 22e magnetically attached to the inner surface of the widened portion 5b, closing the upper end opening of the second branch space 18b. Also, the sliding insulating plate 23a is accommodated in the accommodating portion 24 with the flange portion 23b magnetically attached to the inner surface of the narrow portion 5a directly above the accommodating portion.

[0046] Therefore, under normal conditions, the second branch space 18b is maintained in an insulated state from the charging portion, ensuring safe operation.

[0047] From this state, in order to replace and repair the existing power cable 9, when, for example, a temporary supply cable 41 is connected to a mobile device connection box of a switchgear that was supplying power to the load with the existing power cable and power is continuously supplied additionally during the replacement work of the existing power cable 9, as shown in FIG. 2, the first opening / closing lid 31a is opened, a hand is inserted through the first opening 31, and the connection conductor 8a (shown in FIG. 1) to which the power cable 9 connected in the first branch space 18a is connected is removed. Also, in order to ensure insulation from the charging portion (branch conductor 7), the upper end opening of the first branch space 18a is closed by the rotating insulating plate 21b. Then, the temporary supply cable 41 is drawn into the second branch space 18b, a hand is inserted through the second opening 32, and the pressure contact terminal 42 of this temporary supply cable 41 is connected to the branch conductor 7 via the connection conductor 8b. Note that the temporary supply cable 41 is removed after the existing cable is removed and the laying and connection of the new power cable are completed.

[0048] Also, when directly connecting and supplying the power cable 51 without temporary supply in order to replace and repair the existing power cable 9 from the normal state, as shown in FIG. 3, the power cable 51 is drawn into the empty second branch space 18b, a hand is inserted through the second opening 32, and the pressure contact terminal 52 of this power cable 51 is connected to the branch conductor 7 via the connection conductor 8b. At the same time, insert a hand through the first opening 31 to remove the connection conductor 8a of the cable to be removed, and then cover the upper end opening of the first branch space 18a where the power cable to be removed was installed with the insulating plate 21b, and then remove the power cable 9.

[0049] Also, when bypassing the transformer 2 to supply power from a mobile transformer (not shown) to the existing power cable 9 for inspection and repair of the transformer 2, as shown in FIG. 4, the conductor of the disconnection / connection part 6c of the main circuit conductor 6 is removed, and an insulating plate 23a is slid and arranged between the main circuit conductor 6 and the branch conductor 7. Then, a temporary supply cable 61 is drawn into the second branch space 18b, a hand is inserted through the second opening 32, and the pressure contact terminal 62 of this temporary supply cable 61 is connected to the branch conductor 7 via the connection conductor 8b. As a result, a state is formed in which power is supplied from the mobile transformer to the load connected to the secondary side of the transformer.

[0050] Therefore, according to the above configuration, it is possible to ensure a large space (the first branch space 18a, the second branch space 18b) for connecting and removing the temporary supply cables 41, 61 and the power cables 9, 51. Also, since the work can be performed through the openings 31, 32 directly facing the respective branch spaces, the work can be easily performed. Further, the insulation between the branch space and the charging unit can be easily shielded from the charging unit by moving (rotating or sliding) the insulating plates 21b, 22b, 23a pre-accommodated in the cable duct 1, and the work can be safely performed. Also, since the insulating plates are always accommodated and used in the cable duct, there is no risk of loss.

[0051] In addition, the make-and-break operation of the connection / disconnection portion 6c of the main circuit conductor 6 (the operation of removing and attaching the conductor of the connection / disconnection portion 6c) and the position setting of the slide-type insulating plate 23a can also be performed through the opening 33 provided in the vertical portion 5 (narrow portion 5a) of the cable duct 1, which facilitates the operation.

[0052] In the illustrated example described above, the first branch space 18a and the second branch space 18b are arranged side by side in the extending direction of the horizontal portion of the cable duct. However, they may be arranged side by side in a direction perpendicular to the extending direction of the horizontal portion.

[0053] Also, the configurations of the first insulating mechanism 21 and the second insulating mechanism 22 having the insulating plates 21b and 22b are not limited to those shown in FIGS. 1 to 4, and may be appropriately changed and used. For example, as shown in FIG. 5, the magnets 21d and 22d attached to the swing pieces 21e and 22e may be attached to the surfaces on the opposite sides of the swing pieces 21e and 22e and used.

Explanation of Reference Numerals

[0054] 1 Cable duct 2 Transformer 4 Horizontal portion 5 Vertical portion 6 Main circuit conductor 7 Branch conductor 8 Connection conductor 9 Power cable 13 Partition wall 18a First branch space 18b Second branch space 21 First insulating mechanism 21b Insulating plate 21d, 22d, 23c Magnet 22 Second insulating mechanism 22b Insulating plate 23 Third insulating mechanism 23a Insulating plate 31 First opening 32 Second opening 33 Third opening 41 Temporary supply cable 51 Power cable 61 Provisional supply cable

Claims

1. A cable duct for a transformer, comprising a horizontal portion provided above the transformer and a vertical portion extending downward from the horizontal portion, a main circuit conductor connected to the bushing of the transformer and provided from the horizontal portion to the vertical portion, and a branch conductor connected to the main circuit conductor and to which a connection conductor for connecting a cable can be connected, wherein the branch conductor is housed in the vertical portion, and below the branch conductor in the vertical portion, a first branch space and a second branch space branched by a partition wall are formed, wherein the vertical portion is provided with a first opening facing the first branch space and a second opening facing the second branch space, respectively, and a cable drawn into each of the branch spaces is connectable to the branch conductor via the connection conductor. A cable duct for a transformer is characterized by this.

2. A disconnection and connection portion for disconnecting and connecting the main circuit conductor and the branch conductor is provided in a portion of the main circuit conductor housed in the vertical portion, and the vertical portion is further provided with a third opening through which this disconnection and connection portion can be operated from the outside. The cable duct for a transformer according to claim 1 is characterized by this.

3. Each branch space is provided with a rotary insulating mechanism for shielding the space between the branch conductor and the branch conductor when the connection conductor is not connected to the branch conductor. The cable duct for a transformer according to claim 1 or 2 is characterized by this.

4. Above the branch conductor in the vertical portion, a slide-type insulating mechanism for shielding the space between the main circuit conductor and the branch conductor when the conduction between the main circuit conductor and the branch conductor is interrupted by the disconnection and connection portion is provided. The cable duct for a transformer according to claim 1 or 2 is characterized by this.

5. The rotary insulating mechanism includes an insulating plate that can be rotated between a position where the upper end portion of the branch space is in an open state and a position where it is in a closed state, and a swing piece that is swingably provided at the tip of the insulating plate. The cable duct for a transformer according to claim 3 is characterized in that the tip of the swing piece can be magnetized to the partition wall or the vertical portion of the cable duct.

6. The slide-type insulation mechanism includes an insulating plate slidable between a position where the main circuit conductor and the branch conductor are in an open state and a position where they are in a closed state, and a flange portion fixed to the tip of the insulating plate. The transformer cable duct according to claim 4, characterized in that the flange portion can be magnetized to the vertical portion of the cable duct.

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