JPH0630286B2 - Ground resistance device - Google Patents

Description

The present invention relates to a ground resistance device connected to a neutral point such as a transformer or a generator.

[Background of the Invention]

Generally, a grounding resistance device connected to a neutral point of a device such as a transformer or a generator is constructed as an electric circuit shown in FIG. For example, the other end of the grounding resistor 3 whose one end is connected to the neutral point of the transformer 1 is grounded, and one end of the grounding resistor 3 is connected to one end of the lightning arrester 2 as necessary to prevent ground breakdown of the winding.
It is configured by connecting one end of.

FIG. 8 shows a ground resistance device constructed based on the electric circuit of FIG. 7 and is shown in Japanese Utility Model Laid-Open No. 53-51941.

A metal resistor is formed in the case 30 of the air insulation method to form a unit, insulation is secured by supporting this unit with an insulator 31, and an electrical series is provided by a lead wire 32 between the units at predetermined positions on the insulation. To form a grounding resistor 3. The grounding resistance device having such a configuration is used for the purpose of suppressing the ground fault current of the power system, suppressing the abnormal abnormal voltage, and the like.

The conventional grounding resistance device having such a structure requires a large installation area because the grounding resistor 3 is large as can be seen from FIG.

[Object of the Invention]

An object of the present invention is to provide a ground resistance device which is small in size.

[Outline of Invention]

The present invention is not limited to simply changing the grounding resistor from the aerial insulation method to an insulation method using an insulating medium such as SF ₆ gas or insulating oil. In addition, a ceramic resistance element is laminated in a sealed container in which the insulating medium is sealed. And a laminated body formed by laminating zinc oxide elements are arranged side by side, and the laminated body of the ceramic resistance element is provided at least between the upper and lower mounting brackets that are one end and the other end of the laminated body. The upper and lower mounting brackets are connected in series via one intermediate bracket, and a stack of the zinc oxide elements is connected in series between the upper and lower mounting brackets via the intermediate bracket. It is characterized in that it is composed of a plurality of pieces, and the both laminated bodies are connected at both ends by an upper mounting member and a lower mounting member, respectively, one end of which is led out from the sealed container and the other end is grounded.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a case where the grounding resistance device according to one embodiment of the present invention is connected to the transformer 1.

The neutral point deriving bushing 4 of the transformer 1 and the bushing 6 of the ground resistance device are connected by an overhead wire 5.
The ground resistance device is composed of a ground resistance device 3 and a lightning arrester 2 which are configured in a sealed container 7 in which SF ₆ gas or insulating oil is sealed. As can be seen from the comparison with FIG. 8, the ground resistance device is remarkably small.

Next, the configuration inside the hermetically sealed container 7 of the ground resistance device will be described with reference to FIG.

Upper mounting bracket that is one end of the grounding resistor 3 in the sealed container 7
21 is the central conductor of the bushing 6 via the insulating spacer 18.
It is led out by 20 and the other end is grounded through the lower mounting member 13. Three mounting brackets, that is, an upper mounting bracket 21, an intermediate mounting bracket 11 and a lower mounting bracket 13 are arranged in the sealed container 7 in the axial direction. Are formed. An example of this fitting portion will be described by using the intermediate mounting metal fitting 11 shown in FIGS. 4 and 5 as a representative.
Four fitting protrusions 23 are integrally formed on each of the upper and lower surfaces, which are the opposing surfaces of the. Incidentally, an insulating rod 10 of the lightning arrester 2, which will be described later, penetrates through the central through hole 11a.

As described above, between the three fittings 11, 13 and 21 each having a fitting portion formed on the opposite surface, the insulating cylinder 16 having both ends fitted to the fitting projection 23 as shown in FIG. The insulating cylinder 16 is arranged so as to prevent rotation and is fixed by, for example, a bolt 34. The number of the fitting projections 23 in this example is four.
4 between the upper mounting bracket 21 and the intermediate mounting bracket 11.
Four insulating cylinders 16 are fixed, and a total of four insulating cylinders 16 are fixed between the intermediate mounting bracket 11 and the lower mounting bracket 13. The insulating cylinders 16 and the internal configuration are the same, and a plurality of ceramic resistance elements 15 are axially laminated inside each, and contact pressure is applied by a spring 14 arranged at least at one end to form a laminated body 17. There is. In this way, the ceramic resistance element and the spring 14 or
The grounding resistor 3 is electrically connected by a connection conductor (not shown) arranged in parallel with 14.

The ground resistance device 3 is composed of a laminated body 17 of four ceramic resistance elements that are connected in parallel between the mounting brackets, but can be determined according to the circuit conditions and the characteristics of the ceramic resistance element 15 and the withstand voltage. And a plurality of laminated bodies 17 are connected in parallel according to the resistance value and the like.

The ceramic resistance element 15 is composed of crystal grains made of zinc oxide and crystal grains made of a metal oxide or a metalloid other than zinc, for example, a zinc oxide compound selected from titanium, silicon, antimony, zirconium, and tin. In the composite oxide sintered body to be used, an oxide resistor in which a grain boundary layer having a higher electric resistance than the crystal grains of zinc oxide does not exist between the crystal grains has a large surge resistance, It is preferable in view of the characteristics that the temperature coefficient of resistance is positive and small, and that the resistance value does not change even when exposed to a high temperature of 500 ° C. or higher.

Next, the configuration of the lightning arrester 2 will be described.

Each of the mounting brackets 11, 13, 21 has a through hole formed in the center thereof. For example, through holes 11a are formed in the intermediate mounting member 11, and the insulating rod 10 is inserted into these through holes. A plurality of zinc oxide elements 9 are inserted into the insulating rod 10 to form a laminated body 22. A spring 12 is arranged at the bottom of each of the middle mounting bracket 11 and the upper mounting bracket 21, and the insulating rod 10
By screwing both ends of the above, contact pressure is applied to the zinc oxide element 9 laminated by the spring 12, and the positions of the respective mounting brackets 11, 13, 21 are held. Through the laminated body 22 of the zinc oxide element 9 thus configured, the mounting brackets 11, 13, 21
The two are electrically connected in series.

The ceramic resistance element 15 has a disk shape, but if it has a donut shape like the zinc oxide element 9, it can be supported by an insulating rod instead of the cylinder 16, and conversely as a zinc oxide element 9. If a plate-shaped member is used, it can be supported by using the insulating cylinder 16 like the ceramic resistance element 15.

In the grounding resistance device as described above, a ceramic resistance element 15 which is a high withstand voltage linear resistance is used as a resistance body of the grounding resistor 3, and a sealed container 7 in which an insulating medium such as SF ₆ gas or insulating oil is sealed is used. Since it is configured, the supporting insulator 31 is not required as in the conventional case, and not only the height in the stacking direction but also the installation area can be reduced. Further, since there is no lead wire for connection between the ceramic resistance elements 15 in the laminated body 17, and further, the mounting brackets 11, 13, 21 are used for connecting between the laminated bodies 17 without using the lead wire, It is possible to reduce the inductance due to the line and suppress the voltage jump when an overvoltage such as a surge is applied.

The ground resistance device is also characterized as a combination of the arrester 2 and the ground resistor 3. That is, as shown in FIG. 2 which is a sectional view taken along the line II-II in FIG. 1, the laminated body 17 is juxtaposed and electrically connected in parallel to the outer periphery of the laminated body 22 which constitutes the arrester 2. ing. For this reason,
22 can improve the sharing of the voltage applied to each zinc oxide element under the influence of the potential of the laminated body 17. In this embodiment, since the intermediate mounting member 11 is used and the forcible potential is applied to the intermediate mounting member 11 by the laminated body 17 of the ceramic resistance elements 15, the voltage sharing of the zinc oxide element 9 is further improved.
This is the same even if the number of intermediate mounting members is increased and the number of series-connected stacked bodies of zinc oxide elements and ceramic resistance elements is increased accordingly.

FIG. 6 shows an external view of a grounding resistance device according to another embodiment of the present invention. For example, a connecting bus bar that fluidly and gasally separates the transformer 1 and the grounding resistance device 60 by an insulating spacer 35. Directly connected by 36. Ground resistance device
The inside of the sealed container 7 of 60 is similar to that of FIG. 1, and the central conductor 20 of the bushing 19 of FIG. 1 corresponds to the central conductor of the connecting busbar 36.

According to this embodiment, the lead wire 5 used between the transformer 1 and the grounding resistance device 60 is also unnecessary, and the surge of voltage due to the surge of the lead wire due to the inductance of the lead wire is sufficiently suppressed. You can

〔The invention's effect〕

As described above, according to the present invention, since the laminated body of the zinc oxide element and the laminated body of the ceramic resistance element are arranged in parallel in the same hermetically sealed container in an electrically parallel manner, the device is downsized, The voltage sharing of the zinc oxide element can be improved. Further, since the mounting bracket is arranged in the middle, the seismic resistance and the assembling workability can be improved.

[Brief description of drawings]

1 is a longitudinal sectional view of a grounding resistance device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II--II of FIG. 1, and FIG. 3 is the use of the grounding resistance device of FIG. Fourth front view showing the state
1 is a plan view of the intermediate mounting member of FIG. 1, FIG. 5 is a side view of the intermediate mounting member of FIG. 4, and FIG. 6 is a front view of a grounding resistance device in use according to another embodiment of the present invention. FIG. 7 is a circuit diagram of a ground resistance device, and FIG. 8 is a front view showing a conventional ground resistance device in use. 2 ... Lightning arrester, 3 ... Grounding resistor, 7 ... Sealed container, 9
...... Zinc oxide element, 11 …… Intermediate mounting bracket, 13 …… Lower mounting bracket, 15 …… Ceramic resistance element, 17 …… Layered body, 21
...... Upper mounting bracket, 22 …… Layered body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Sasaki 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture Kokubun Plant, Hitachi, Ltd. (72) Inventor Takeo Yamazaki 3-chome, Sachimachi, Hitachi City, Ibaraki Prefecture No. 1 in Hitachi Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-55-102189 (JP, A) JP-A-56-144503 (JP, A)

Claims (2)

[Claims] 1. A laminated body formed by laminating ceramic resistance elements and a laminated body formed by laminating zinc oxide elements are juxtaposed in a hermetically sealed container enclosing an insulating medium. A stack of a plurality of zinc oxide elements, the plurality of which are connected in series between the upper and lower mounting brackets through at least one intermediate bracket provided between the upper and lower mounting brackets that are one end and the other end of the laminate. The body is composed of a plurality of the upper and lower mounting brackets connected in series via the intermediate mounting bracket, and the two laminated bodies are connected in parallel at both ends by the upper mounting bracket and the lower mounting bracket, respectively, and one end thereof is A ground resistance device which is led out from the above-mentioned sealed container and whose other end is grounded. 2. Between the upper mounting bracket and the intermediate mounting bracket,
There is one laminated body of the zinc oxide element arranged between the intermediate metal fittings and between the lower metal fittings, respectively, and between the upper mounting metal fittings and the intermediate metal fittings, and between the intermediate metal fittings and the lower metal fittings. The ground resistance device according to claim 1, wherein the laminated body of the ceramic resistance elements includes a plurality of laminated bodies surrounding the laminated body of the zinc oxide elements.