JPH0997701A - Neutral resistance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the thermal cracking of an insulating gas insulating and cooling a resistor caused by the heating of the resistor when the resistor is supplied with power in a tank. SOLUTION: A specific numbers of cooling ducts 14 where an insulating gas is flowing are provided in a resistor 6 made of a specific number of resistance sheets stacked through the intermediary of insulating members 9. Besides, the periphery of the resistance sheets is encircled with strip type sheets made of the same quality material as that of the insulating members 9 so that the heat generated by the power supply to the resistor 6 may be cooled down by the insulating gas flowing inside the cooling ducts 14. In reverse, the radiation from the peripheral edge of the resistance sheets is suppressed by the sealing sheets so that the whole resistor 6 may be cooled down in well balance due to even temperature distribution thereby enabling the rapid rise in temperature of the insulating gas causing thermal cracking to be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a neutral point grounding resistance device for electric power for grounding a neutral point of a transformer winding through a resistance device.

[0002]

2. Description of the Related Art A conventionally known neutral grounding resistance device is composed of, for example, a plurality of resistors formed by arranging resistive elements in a grid in a case.
At the time of installation, the individual resistors are connected in series and are installed in a horizontal row with a support insulator. Among these resistors, the resistor in the front row is the neutral point of the transformer winding. ,
The resistors in the last row are each connected to the ground wire. Since each resistor that constitutes the resistance device is only insulated and cooled by the air insulation method, the case itself becomes a high voltage when the ground-to-ground potential at the neutral point rises. There is a protective fence around the area for safety reasons.

However, since the resistance device adopts the air insulation method, it is difficult to prevent the device itself from becoming large. Further, since the resistance element comes into contact with the outside air, there is a problem that the resistance element deteriorates when used in a place with bad atmosphere such as a salt-damaged area.

[0004]

In recent years, in order to solve the above-mentioned problems, a resistor formed by laminating a predetermined number of resistive element plates in a plurality of layers with an insulating member interposed is provided in a sealed tank. A resistance device which is housed and installed and in which a constant amount of an insulating gas such as SF ₆ gas is filled in the tank is used. However, in the resistance device filled with the insulating gas, when a current flows through the resistive element plate, the heat corresponding to the resistance component is directly dissipated from the resistive element plate and the temperature of the insulating gas rapidly rises. As a result of the abnormally high pressure, it was necessary to use an expensive tank with excellent pressure resistance.

Further, when the temperature of the resistive element plate rises, the insulating gas is decomposed by the temperature and toxic decomposed gas is generated and accumulated in the tank. As a result,
Not only is it difficult to lower the temperature of the resistive element plate, but also the decomposed gas comes into contact with the resistive element plate and the insulating member, which deteriorates and damages these members and shortens the life of the resistance device.

Further, since the resistor element plate is formed by interposing the insulating member over a plurality of layers to form the resistor, the heat of the resistor element plate is hidden inside the resistor and it is difficult to cool it.
If the resistance device operates again before the temperature of the resistive element plate drops, the temperature of the resistive element plate rises above the allowable temperature, possibly damaging the resistor itself.

In view of the above-mentioned various problems, the present invention suppresses the temperature rise of the resistance element plate caused by the current flowing through the resistor, and when the insulating gas is thermally decomposed by the heat generation of the resistance element plate, It is an object of the present invention to provide a neutral grounding resistance device having a simple structure in which an insulating member covering a resistive element plate is prevented from deteriorating its insulating performance due to decomposed gas.

[0008]

In view of the above-mentioned problems, the present invention provides a resistance element body by laminating a plurality of resistance element plates through a sheet-shaped insulating member and providing these resistance element bodies with required layers. A resistor is provided by arranging a cooling duct for each stack and surrounding the peripheral edge of the resistive element plate by interposing strip-shaped seal plates on the outer peripheral edge of the resistive element plate interposed between the insulating members. To form. Then, the resistor is mounted and fixed on a support insulator attached to the bottom of the tank through a lower support plate, and an upper support plate is mounted on the upper side of the resistor. The support plate is fastened by using an insulating fastening stud bolt or a porcelain insulator made of a synthetic resin, so that a resistor provided by stacking a plurality of resistor elements is properly sandwiched and fixed. After that, an insulating gas such as SF ₆ gas is filled in a fixed amount in the tank to form a resistance device.

[0009]

In the resistance device having the above structure, when an accident such as a one-line ground fault occurs, a ground fault current flows into the resistance element plate and the resistance element plate heats up to raise its temperature. Since the insulating gas flows through the cooling duct formed in each of the required layers, the inside of the resistor can be cooled well. On the other hand, since the outer peripheral edge of each resistor element constituting the resistor is surrounded by the strip-shaped seal plate, it is possible to favorably prevent the heat of the resistor element plate from radiating from this portion.

As a result, the inside of the resistor can be satisfactorily cooled by the cooling duct, while heat dissipation from the periphery of the resistive element plate, which is likely to come into contact with the insulating gas, can be easily suppressed, so that the entire resistor is Since it is possible to cool in a well-balanced manner with an almost uniform temperature distribution, it is possible to suppress and mitigate the temperature rise of the insulating gas due to rapid heat dissipation from the resistor, and effectively prevent the pressure rise in the tank. be able to.

Further, since the insulating gas rarely comes into contact with the resistive element plate, it is possible to satisfactorily avoid / suppress the problem that the insulating gas is thermally decomposed due to the temperature rise of the resistive element plate to generate decomposed gas. Since it is almost impossible to deteriorate the insulation performance of the insulation member due to the generation of decomposed gas, and the insulation of the resistor is impaired by this, it is possible to extend the life of this type of resistance device and repeat its operation (use). Can be done smoothly.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, 1 is, for example, a transformer installed in a substation, 2 is a neutral point installed resistance device (hereinafter referred to as a resistance device) of the present invention installed beside the transformer 1, and the resistance device 2 is Via the insulator 3 on the input side, the neutral point bushing 4 of the transformer 1 is connected using a connection cable 5. As shown in FIG. 1, the resistance device 2 includes a resistor 6 formed by laminating a predetermined number of resistance element plates described below,
This resistor 6 is housed and installed, and it is roughly configured by a tank 7 shown in FIG. 1 in which insulating gas such as SF ₆ gas is quantitatively filled.

Next, the structure of the resistor 6 will be described. As shown in FIGS. 3 and 4, the resistor 6 includes a plurality of flat resistance element plates 8 obtained by punching a conductive metal plate such as a stainless steel plate into a zigzag shape, and the resistance element plates 8 from the vertical direction. A resistor element body 10 formed by using a pair of mica, alumina, silica sheet-like insulating members 9 having a wider heat resistance than the sandwiched resistor element plates 8 and having a required number of layers (this embodiment). (3 layers in the example) are laminated in a plurality of layers.

As shown in FIGS. 3 to 5, the resistor element 10 has a resistor element plate 8 on the lower insulating member 9 and a margin of a constant dimension L whose outer peripheral edge is inward from the peripheral edge of the insulating member 9. And then the same thickness as that of the resistance element plate 8 in the margin between the peripheral edge of the insulating member 9 and the outer peripheral edge of the resistance element plate 8 and the same quality as the insulating member 9. The strip-shaped heat-resistant sealing plates 11 and 11a made of a material are arranged, and then the upper insulating member 9 is aligned with the lower insulating member 9 as shown in FIG. The resistor element body 10 is formed by placing the resistor element body 10 on the substrate 8. The seal plate 11
When mounting the resistance element plate 8 on the insulating member 9 on the lower side, after mounting the resistance element plate 8 on the insulating member 9, the sealing plates 11, 11a
As shown in FIG. 4, the lower insulating member 9 is placed on a marginal portion, and these are fixed by using, for example, a heat resistant adhesive. The input terminal 8a and the output terminal 8b of the resistor element plate 8 are
As shown in FIG. 4, the length dimension of the seal plate 11a located on the pull-out direction side should be shorter than the length of the other seal plates by the dimension that the terminals 8a, 8b can be led out. Can be easily pulled out as shown in FIG. Further, the seal plates 11 and 11a themselves are the resistance element plates 8
Is fixed to the insulating member 9 in close contact with the peripheral edge thereof.

After the resistor element body 10 is formed as described above, the resistor element body 12 is provided by laminating a plurality of layers (three layers in this example) of the resistor element body 10. In this case, the resistor element 1
The resistive element plates 8 of each layer forming 0 are arranged such that the input terminal 8a and the output terminal 8b are interleaved in each layer because they are electrically connected in series. When the necessary number of resistor elements 12 are formed, as shown in FIG. 3, between the insulating members 9 located between the resistor elements 12, as shown in FIG. Rails 13 made of mica, alumina, etc. are arranged in parallel at predetermined intervals, and in this state, the resistor element bodies 12 are laminated in required layers to form a cooling duct 14 between the resistor element bodies 12. To form.

After the cooling duct 14 is provided between the resistor element bodies 12, the resistor element 6 is formed by stacking a predetermined number of the resistor element bodies 12. When the resistor 6 is configured as described above, the output terminal 8b of the resistance element plate 8 protruding from each resistance element body 10 and the input terminal 8a of the resistance element body 10 of the previous layer.
By connecting and by welding, that is, by connecting the resistance element plates 8 of the resistance element bodies 10 of each layer in series, the assembly of the resistor 6 is completed. The input / output terminals 8a, 8a,
When connecting 8b, you may make it connect at the stage of forming the resistor element body 12 before assembling the said resistor 6 as needed.

When the resistor 6 is assembled, the resistor 6 is mounted on the support insulator 16 in the tank 7 via the lower support plate 17, and the upper support plate 1 arranged on the upper side of the resistor 6 is mounted.
8 and the lower support plate 17 are clamped and fixed by using an insulating sudd bolt 19 for tightening, and the resistor 6 is clamped and fixed by the upper and lower support plates 18 and 17. The upper and lower support plates 18 and 17 may be attached when the assembly of the resistor 6 is completed. Also, in FIG.
Is an electric field relaxation shield attached to the upper support plate 18.
Further, 21 shown in FIG. 1 is a connection conductor for connecting the upper support plate 18 of the resistor 6 and the input side insulator 3, and 22 is the lower support plate 1
7 is a connection conductor for connecting the output side insulator 23, and the connection conductor 22 is grounded through the ground wire 24 to the ground. After the resistor 6 is assembled in the tank 7 as described above, the tank 7 is filled with an insulating gas such as SF ₆ gas at a predetermined pressure.

Next, the operation will be described. When a one-wire ground fault or the like occurs in the power transmission system and a large current flows from the neutral point bushing 4 of the transformer 1 to the resistor 6 through the connecting cable 5 → the connecting conductor 21 for several seconds, the resistors 6 are formed. The resistive element plate 8 generates heat according to its resistance amount or electric power.
The heat generated in each resistance element plate 8 tends to be dissipated to the outside of the resistor 6. In this case, a heat-resistant insulating member 9 is interposed between the resistance element plates 8 and, moreover, the peripheral edges of the resistance element plates 8 are surrounded by strip-shaped seal plates 11 and 11a, so that the resistance element plates 8 are formed. Heat is gradually dissipated.

On the other hand, a cooling duct 14 is formed between the resistor elements 12 provided by laminating a plurality of resistance element plates 8 and the cooling duct 14 is constantly filled with an insulating gas. Therefore, the heat generated in each resistor element body 12 is conversely gradually cooled by the insulating gas filling the cooling duct 14 without being accumulated therein.
Also in this case, the heat of the resistive element plate 8 is not directly cooled by the insulating gas, but passes through the insulating member 9 and the cooling duct 14
The insulating gas takes away the heat that is gradually dissipated in the interior of the resistor 6 to gradually cool it.

As described above, the heat generated in the resistance element plate 8 is not rapidly radiated from the resistance element plate 8, but gradually passes through the cooling duct 14 and the seal plates 11 and 11a surrounding the resistance element plate 8. Since it is transferred to the insulating gas, the insulating gas is heated by the heat of the resistive element plate 8 without being thermally decomposed. As a result, the insulating gas can effectively prevent the temperature and pressure from rapidly increasing due to the heat generated when the resistance element plate 8 is energized with a current. Therefore, the insulating gas can be well suppressed from being thermally decomposed by the heat generated when the resistive element plate 8 is energized, and its insulating performance can be maintained without deteriorating, and the generation of the decomposed gas can be suppressed. It is possible to favorably avoid deterioration and damage of the member 9 and the resistance element plate 8.

Although the present invention has been described in the structure in which the cooling duct 14 provided in the resistor 6 allows the insulating gas to flow in the lateral direction as shown in FIG. 3, the present invention is not limited to this, and the resistor 6 itself is oriented vertically. Alternatively, the cooling duct 14 may be positioned in the vertical direction so that the insulating gas at the time of heat generation of the resistance element plate 8 is circulated vertically in the tank 7 to enhance the cooling effect of the resistance element plate 8.

[0022]

As described above, according to the present invention, since the cooling duct through which the insulating gas flows in the resistor is formed at the required position of the resistor, the resistor is capable of generating the heat generated inside when the resistor is energized. Good cooling can be achieved by the insulating gas flowing in the cooling duct.

Further, the resistance element plate constituting the resistor is surrounded by a heat-resistant strip-shaped sealing plate between the insulating members in the vertical direction, so that the resistance element plate generates heat when energized. At this time, it is possible to suppress the heat of the resistance element plate from being dissipated to the outside, so that it is possible to satisfactorily suppress and mitigate the sudden rise in temperature and pressure of the insulating gas due to the heat generation of the resistance element plate. .

As described above, in the present invention, when the resistor generates heat by energization, the heat inside the resistor is cooled by the insulating gas flowing in the cooling duct, and the peripheral edge of the resistor element plate constituting the resistor is On the contrary, the heat dissipation from the resistance element plate is suppressed by being surrounded by the seal plate, so that the resistor itself does not instantly dissipate the heat generated by energization, but it cools in a well-balanced manner with a uniform temperature distribution. The thermal decomposition of the insulating gas can be effectively suppressed, and the deterioration and damage of the insulating member can be suppressed by this so that the resistor can be used repeatedly and its life can be increased. It is convenient and convenient.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a usage state of a neutral grounding resistance device of the present invention.

FIG. 2 is a side view of a resistor.

FIG. 3 is a perspective view showing a process of manufacturing a resistor.

FIG. 4 is an exploded perspective view of a main part of a resistor.

FIG. 5 is a plan view showing a mounting state of a resistance element plate.

FIG. 6 is a front view showing a main part of a resistor in a vertical section.

[Explanation of symbols]

 2 resistance device 6 resistor 7 tank 8 resistance element plate 9 insulating member 10 resistance element body 11 seal plate 12 resistor element body 14 cooling duct

Claims (2)

[Claims] 1. A neutral point grounding in which a resistor element plate is sandwiched and covered by a heat-resistant sheet-like insulating member in a tank filled with an insulating gas, and a resistor formed by laminating a plurality of layers is housed and installed. In the resistance device, a neutral point grounding resistance device, characterized in that a cooling duct for circulating an insulating gas in the resistor is provided between predetermined layers of an insulating member sandwiching the resistive element plate of the resistor. 2. A strip-shaped seal plate having excellent heat resistance is provided on the periphery of the resistance element plate sandwiched and covered by the insulating member so as to surround the periphery of the resistance element plate. The neutral grounding resistance device according to claim 1.