JPH04290204A - Nonlinear resistor - Google Patents

Abstract

PURPOSE:To provide a highly reliable nonlinear resistor which prevents the drop of electric property at the time of making a high-resistance layer at the side of a zinc oxide element. CONSTITUTION:In a nonlinear resistor wherein a high-resistance layer is provided at the side of a zinc oxide element 1 having zinc oxides for its main ingredients, the high-resistance layer is constituted by stacking a first high- resistance layer 2, which has iron oxides or silicon oxides, antimony oxides, and bismuth oxides as its main ingredients, a second high-resistance layer 3, which has inorganic polymers as its main ingredients, and a third high-resistance layer 4, which consists of an amorphous layer, in order.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention relates to a non-linear resistor mainly composed of zinc oxide used in lightning arresters, etc., and in particular improves the high resistance layer provided on the side surface of the zinc oxide element to increase the discharge withstand. This invention relates to a nonlinear resistor with improved characteristics.

0003

2. Description of the Related Art For example, in power systems, lightning arresters are generally used to protect the power system by suppressing abnormal voltages generated in the power system. Further, this lightning arrester is equipped with a non-linear resistor that exhibits insulation characteristics under normal voltage and exhibits low resistance characteristics when abnormal voltage is applied to protect the power system. This non-linear resistor is generally called a varistor, and a well-known representative example is one whose main component is zinc oxide, which is a metal oxide.

Conventionally, nonlinear resistors made of metal oxides used in lightning arresters and the like have generally been formed in the following manner.

[0005] The nonlinear resistor has zinc oxide (ZnO) as its main component, and contains zinc oxide, bismuth (Bi), and antimony (
After thoroughly mixing raw materials consisting of oxides such as Sb), cobalt (Co), manganese (Mn), nickel (Ni), chromium (Cr), and silicon (Si) with water and an organic binder, this mixture is passed through a spray dryer. It is granulated, molded and sintered. Thereafter, a high-resistance material for preventing creeping flash is applied to the side surface of this sintered body (zinc oxide element body) and re-sintered to form a high-resistance layer. Furthermore, a non-linear resistor was formed by polishing both the upper and lower end surfaces of this sintered body and attaching electrodes.

[0006] To explain in more detail the high resistance layer formed on the side surface of the non-linear resistor, for example, iron oxide (
Fe2O3) or silicon dioxide (SiO2),
Bismuth oxide (Bi2 O3) and antimony oxide (
Sb2O3) etc. were mixed with water and an organic binder, this mixture was applied to the side surface of the sintered body (zinc oxide body), and then fired at 1000°C to 1200°C to form a high-resistance layer. .

By the way, in recent years, electric power systems have become larger in capacity and higher in voltage, and along with this, the capacity of non-linear resistors constituting lightning arresters has been increased, and the thickness and area of non-linear resistors have increased. The amount has been increased.

[0008]

[Problems to be Solved by the Invention] However, such a large nonlinear resistor undergoes considerable deformation during sintering, and not only is it impossible to obtain a predetermined shape, but also the nonlinear characteristics are There is a problem that deterioration of electrical characteristics such as deterioration, variation, and dispersion of discharge withstand capacity also occurs.

[0009] Here, it has been considered to coat the sides of the nonlinear resistor with silicone resin, epoxy resin, etc., but with organic materials coated in this way, the nonlinear resistance value against continuous current flow is cannot be stabilized sufficiently. In addition, a non-linear resistor is being considered that is stable against continuous energization and free from creeping flash by forming a glass layer after forming a high-resistance layer on a sintered body. In products with a glass layer formed in this way, the glass coated on the side surface of the sintered body is easily broken, and the adhesion is low, so the area of the side surface of the sintered body is small, and the discharge resistance is low. The dispersion becomes large. Furthermore, forming a high-resistance layer mainly composed of inorganic phosphates such as aluminum phosphate has been considered, but in this case too, the discharge withstand characteristics would be insufficient and highly variable. This was the current situation.

The present invention has been made in consideration of the above-mentioned circumstances, and provides a highly reliable nonlinear resistor that prevents deterioration of electrical characteristics when a high resistance layer is formed on the side surface of a zinc oxide element. The purpose is to [Structure of the invention]

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a non-linear resistor in which a high resistance layer is provided on the side surface of a zinc oxide element mainly composed of zinc oxide.
The high resistance layer is a first high resistance layer containing iron oxide, antimony oxide, and bismuth oxide as main components, a second high resistance layer containing an inorganic polymer as a main component, and an amorphous layer. 3 high resistance layers are sequentially laminated.

[0012] Here, silicon oxide may be used instead of iron oxide as the first high-resistance layer.

[0013]

[Function] According to the present invention configured as described above, by forming a high resistance layer with high strength and good stability on the side surface of the zinc oxide element whose main component is zinc oxide,
It is possible to improve the discharge withstand characteristics as a non-linear resistor.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 shows a cross-sectional view of a non-linear resistor, and this non-linear resistor has iron oxide, antimony oxide, and bismuth oxide on the side surface of a zinc oxide element (zinc oxide element) 1. While sequentially laminating a first high-resistance layer 2 containing an inorganic polymer as a main component, a second high-resistance layer 3 containing an inorganic polymer as a main component, and a third high-resistance layer 4 consisting of an amorphous layer, Electrodes 5 are formed on both sides. Next, the nonlinear resistor is manufactured as follows.

That is, zinc oxide (ZnO), bismuth oxide (Bi2 O3), manganese dioxide (MnO2)
, silicon dioxide (SiO2) and chromium oxide (Cr2)
1 mol % of each of O3) is added, and these raw materials are placed in a mixing device together with water and an organic binder as a dispersant and mixed. Next, this mixture is sprayed and granulated using a spray dryer to a predetermined particle size, for example, 100 μm. Then, this granulated material is placed in a mold and pressurized to form a predetermined shape such as a disk, for example, φ50×t30, thereby producing a molded body. Then, the molded body thus obtained is fired at, for example, about 1050° C. to obtain the zinc oxide element (calcined body) 1.

[0017] On the side surface of the zinc oxide element (calcined body) 1, which is the zinc oxide element body obtained in this way, a first
Apply a high resistance layer slurry using a spray gun. This first high-resistance layer slurry was adjusted as follows. This high resistance slurry contains iron oxide, antimony oxide,
Bismuth oxide, Fe2 O3 and Sb2 O, respectively
3, converted to Bi2 O3, Fe2 O3 is 1
0 to 60 mol%, Sb2O3 is 5 to 50 mol
%, Bi2O3 was in the range of 2 to 20 mol%, and pure water was added to make a suitable slurry. At this time, the strength of the coating film can be improved by adding a binder such as polyvinyl alcohol. And zinc oxide element (calcined body) coated with high resistance layer slurry
1 is fired at approximately 1050° C. to 1200° C. to form a first high resistance layer 2 on this side surface.

[0018] The above-mentioned first sintered material obtained in this way
On the surface of the high resistance layer 2, aluminum and phosphorus are converted into Al2O3 and P2O5 respectively.
3 is 30-70 mol%, P2O5 is 10-60
A second high-resistance layer slurry made of a phosphate aqueous solution containing mol % is applied using a spray gun or the like. and,
The sintered material coated with this slurry is heated to approximately 200°C to 45°C.
The second high resistance layer 3 is formed on the surface of the first high resistance layer 2 by firing at 0°C.

A predetermined amount of third high-resistance layer slurry consisting of a butanol solution of tributoxyaluminum is applied onto the surface of the second high-resistance layer 3 of the sintered material thus obtained using a spray gun or the like. Apply. Then, the sintered material coated with this slurry is fired at about 150°C to 450°C to form the third high-resistance layer 4 on the surface of the second high-resistance layer 3.

Both surfaces of the sintered body thus obtained are polished, and electrodes 5 are formed on both surfaces by thermal spraying of aluminum to obtain the nonlinear resistor shown in FIG. 1.

FIG. 2 shows the discharge withstand characteristics of the nonlinear resistor thus obtained. Here, the discharge withstand characteristic is shown by the pass rate of the element when a predetermined impulse current is applied to the non-linear resistor with a waveform of 4/10 μs, and the current value of the applied impulse current is shown on the horizontal axis. The vertical axis shows the pass rate of each element at that time.

For comparison, a conventional example in which a high-resistance layer made of iron oxide, antimony oxide, and bismuth oxide was formed, and a glass layer made of lead glass was further formed on the high-resistance layer was used as Conventional Example 1. Conventional example 2 is a conventional example in which a high-resistance layer made of phosphate containing aluminum is formed.
The discharge withstand characteristics of each are also shown at the same time.

From the results shown in FIG. 2, it can be seen that a first high-resistance layer 2 made of iron oxide, antimony oxide, and bismuth oxide is formed on the side surface of the zinc oxide element 1, and a second high-resistance layer 2 made of phosphate containing aluminum is formed on the side surface of the zinc oxide element 1. It can be seen that the non-linear resistor of this example in which the layer 3 and the amorphous third high-resistance layer 4 made of fired tributoxyaluminum are formed has a better discharge withstand capacity than the conventional example.

The reason why a non-linear resistor having better withstand characteristics than the conventional example was obtained in this example is considered to be as follows.

In Conventional Example 1, since the material coated on the side surface of the sintered body is glass, it is easily broken and has low adhesion, so it is likely to be subjected to impact during the manufacturing process and cause minute scratches. It is considered that these scratches are the cause of the inability to sufficiently withstand thermal stress generated by application of impulse current.

On the other hand, in this example, since a phosphate aqueous solution containing aluminum is applied and fired, the alumina layer and phosphoric acid in the solution form AlPO4, which is connected three-dimensionally. As a result, the second high resistance layer 3 is formed.

[0027] Furthermore, when the tributoxyaluminum coated thereon is heated, 2Al(OC4 H9)3 → Al2 O3
It is thought that a decomposition reaction occurs with +3/2 C4 H9 OH+olefin, and the third high-resistance layer 4 of Al2 O3 is formed. Since tributoxyaluminum is an alcohol solution, it has good permeability, and enters into defective parts such as bores and pinholes in the second high-resistance layer 3 and hardens. Furthermore, since it is a non-crystalline substance, it can fill in defective areas without any gaps. Therefore, the third high-resistance layer 3 with good insulation can be formed.

The second and third high-resistance layers 3 and 4 have greater strength than glass and also have good adhesive properties. therefore,
It is thought that the withstand characteristics were improved because the material could sufficiently withstand the thermal stress generated by the application of an impulse current.

In Conventional Example 2, a high-resistance layer made of a phosphate containing aluminum is directly formed on the side surface of a sintered body (zinc oxide element) containing zinc oxide as a main component. Here, at the boundary between the zinc oxide element and the high resistance layer, the electrical resistance
Since electrical properties such as dielectric constant become discontinuous, electric field concentration tends to occur, and it is considered that sufficient withstand characteristics cannot be obtained.

In contrast, the first high resistance layer 2 of this embodiment
is formed by applying a material consisting of iron oxide, antimony oxide, and bismuth oxide to the side surface of the zinc oxide element 1 and firing it. During firing, zinc oxide in the zinc oxide element 1 reacts with iron oxide, antimony oxide, and bismuth oxide to form a high-resistance layer (first high-resistance layer 2).
) is formed. Therefore, from the zinc oxide element 1 to the first
Electrical properties such as electrical resistance and dielectric constant change continuously throughout the high-resistance layer 2 . In addition, the first high resistance layer 2
There is no major difference in electrical properties such as electrical resistance and dielectric constant between the second high-resistance layer 3 and the second high-resistance layer 3. Furthermore, since the third high resistance layer 4 is formed, the insulation properties are good.

[0031] Therefore, electric field concentration is unlikely to occur and the insulation is good, so it is considered that sufficient withstand characteristics can be obtained.

In this example, a phosphate aqueous solution containing aluminum is used as the second high-resistance layer material, but even if silicon or magnesium is used instead of aluminum, It has been confirmed that even in the case of using silicon in addition to the above, the discharge withstand capacity is improved in the same way as the results shown in FIG. That is, a general phosphate can be used as the second high-resistance layer material.

[0033]Although a butanol solution of tributoxyaluminum is used as the third high-resistance layer material,
Butyl group is replaced with ethyl group, methyl group, propyl group, and aluminum is replaced with silicon, titanium,
It has been confirmed that even when common metal alkoxides such as zirconium, manganese, antimony, calcium, lead, bismuth, and boron are used, the discharge withstand capacity is improved similarly to the results shown in FIG. That is, a general metal alkoxide can be used as the third high resistance layer material.

Furthermore, even if a general phosphate is used as the second high-resistance layer material and a general metal alkoxide is used as the third high-resistance layer material, and a combination thereof is used, the result shown in FIG. It has been confirmed that the discharge withstand capacity is improved in the same way as the results shown in .

In the above embodiment, an oxide material is used as the slurry raw material for the sintered body, but any material that becomes an oxide when sintered may be used, such as hydroxide, carbonate, Similar results can be obtained with oxaloxides. Furthermore, additives other than those shown in the above examples may be added.

[0036]Although this embodiment shows a case of φ50 x t30, it goes without saying that the same effect can be obtained with a case of other dimensions.

In the above embodiment, an example is shown in which the first high-resistance layer 2 is made of a material mainly composed of iron oxide, antimony oxide, and bismuth oxide.
The high-resistance layer 2 can also be formed of a material containing silicon oxide, antimony oxide, and bismuth oxide as main components.

When forming the first high resistance layer 2 using silicon oxide instead of iron oxide, the first high resistance layer slurry may be silicon oxide, antimony oxide,
Bismuth oxide is SiO2, Sb2O3,
Converted to Bi2 O3, Fe2 O3 is 10-8
0 mol%, Sb2O3 is 5-50 mol%, B
i2O3 may be in the range of 2 to 20 mol% and pure water may be added to form a suitable slurry.

Even in the non-linear resistor formed in this manner, the discharge withstand capacity can be improved as in the result shown in FIG.

[0040]

As described above, according to the present invention, a first high-resistance layer containing iron oxide, silicon oxide, antimony oxide, and bismuth oxide as main components and an inorganic high-resistance layer are provided on the side surfaces of a zinc oxide element. By forming a high resistance layer by sequentially laminating a second high resistance layer mainly composed of molecules and a third high resistance layer consisting of an amorphous layer, the discharge withstand characteristics as a non-linear resistor can be improved. It has the effect of improving the

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a non-linear resistor showing an embodiment of the present invention.

FIG. 2 is a graph showing the discharge withstand characteristics of the above example in comparison with the conventional one.

[Explanation of symbols]

1 Zinc oxide element 2 First high resistance layer 3 Second high resistance layer 4 Third high resistance layer 5 Electrode

Claims (2)

[Claims] 1. A non-linear resistor in which a high resistance layer is provided on the side surface of a zinc oxide element containing zinc oxide as a main component, in which the high resistance layer is formed of a zinc oxide element containing iron oxide, antimony oxide, and bismuth oxide as main components. A non-linear film characterized by being constructed by sequentially laminating a first high-resistance layer, a second high-resistance layer mainly composed of an inorganic polymer, and a third high-resistance layer made of an amorphous layer. resistor. 2. A non-linear resistor in which a high resistance layer is provided on the side surface of a zinc oxide element containing zinc oxide as a main component, wherein the high resistance layer is made of a zinc oxide element containing silicon oxide, antimony oxide, and bismuth oxide as main components. A non-linear film characterized by being constructed by sequentially laminating a first high-resistance layer, a second high-resistance layer mainly composed of an inorganic polymer, and a third high-resistance layer made of an amorphous layer. resistor.