JPH01290204A - Manufacture of nonlinear resistor - Google Patents

Abstract

PURPOSE:To enhance a nonlinear characteristic and a discharge-resistant characteristic by a method wherein nickel oxide whose particle radius is specified is used as a nickel raw material. CONSTITUTION:Nickel oxide is used as nickel in an auxiliary component; its particle radius is set to 0.2 to 1.5mum. The nickel oxide which has been dispersed evenly in zinc oxide(ZnO) during a mixing operation reacts evenly with a grain boundary layer composed mainly of a spinel particle (Zn7Sb2O12) or Bi2O3 of a crystal particle width of the zinc oxide during a sintering process. Accordingly, it can be dispersed homogeneously; a sintered substance having a homogeneous grain boundary layer can be obtained during a baking process. By this setup, it is possible to obtain a nonlinear resistor whose nonlinear characteristic in a small electric current region is good and whose durability against an impulse surge is strong.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a non-linear resistor mainly composed of zinc oxide used in lightning arresters, etc. This invention relates to improving the form of nickel raw material added as a component.

(Prior Art) Lightning arresters are used to protect the power system by suppressing abnormal voltages generated in the power system.

Lightning arresters exhibit insulating properties at normal voltage.

A nonlinear resistor is used that has a low resistance value when an abnormal voltage is applied.

A non-linear resistor is generally called a varistor, and a typical example thereof is one whose main component is zinc oxide.

Non-linear resistors made of metal oxides, which are generally used in lightning arresters etc., have zinc oxide (ZnO) as the main component, and also contain bismuth (Bi), antimony (sb), and cobalt (Co).
), manganese (Mn), chromium (Cr), nickel (N
i).

It contains components such as silicon (Si) and aluminum (AQ), and is manufactured by mixing, granulating, molding, and sintering these raw materials, and attaching electrodes to both ends.

More specifically, after thoroughly mixing zinc oxide and the oxide or the subcomponent raw materials that will replace the oxide through sintering, together with water and an organic binder.

Dry and granulate using a spray dryer, etc., and pass the resulting granulated powder through a sieve to remove coarse particles and secondary agglomerated particles.
Place it in a mold and sinter it. A manufacturing method is known that eliminates voids and pinholes that occur inside a resistor and prevents a decrease in surge resistance and energized life. (Unexamined Japanese Patent Publication No. 59-6540
(Refer to 5) (Problem to be solved by the invention) In recent years, electric power systems have become larger in capacity and higher voltage in order to reduce power transmission costs, and with this, 500XV lightning arresters have been put into practical use, and in the near future 1000V ( tlHV)
Lightning arresters are also planned.

The nonlinear resistors used in these lightning arresters must handle extremely large amounts of energy.

Measures such as increasing the capacity of non-linear resistors and increasing the number of parallel-connected resistors are used.

However, an increase in the number of parallel-connected resistors is limited to a few because of characteristic problems such as a tendency to cause an imbalance in current sharing, which inevitably leads to an increase in the capacity of the nonlinear resistor. However, since the thickness is limited by the limiting voltage of the lightning arrester, etc., the diameter must be increased.

In this way, the shape of one nonlinear resistor for 500 KV and 100 OKV has a diameter of Φ100 to Φ140II! *The thickness can be as large as t20" or t60m due to deformation during sintering and economic efficiency.Sintering of such non-linear resistors is difficult and often results in worsening of non-linear characteristics and variations in discharge capacity characteristics. , a stable manufacturing method was desired.

The present invention has been made in consideration of the above points.

The purpose is to provide a method for manufacturing a nonlinear resistor that achieves stabilization and homogenization during sintering and improves nonlinear characteristics and discharge withstand characteristics.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, the nickel raw material is nickel oxide (Nip), and the particle radius is 0.2 to 1.5p. Features.

(for production) The nickel raw material is nickel oxide (Nip).

According to the present invention, which uses particles with a particle radius of 0.2 to 1.5 mm, the nickel oxide that is uniformly dispersed in zinc oxide (ZnO) during mixing changes the grain width of the zinc oxide during the sintering process. Spinel particles (Zn, sb, o12) and Bi
, 0. In order to uniformly react the grain boundary layer mainly composed of .

(Example) An example of the method for manufacturing a non-linear resistor of the present invention will be described below.
This will be explained with reference to FIGS. 1 and 2.

Bismuth oxide (B1203), cobalt oxide (Coo)
, manganese dioxide (MnO, ), chromium oxide (Crt)
03), 0.5 mol% each of silicon dioxide (SiO2), 1 mol% of antimony oxide (Sb, 03), and 0.0025% by weight of 7/L/minium oxide (AI120.) to produce nickel oxide. By changing the thermal decomposition temperature in the step, 1 mol% of each nickel oxide with a particle radius of 0.05 to 5 μs as shown in Table 1 and the remaining zinc oxide are weighed accurately.

Weigh to add a further trace amount of boron oxide (8,03).

Table 1 These raw materials are mixed together with water and organic binders such as a dispersant, a binder, and a lubricant in a mixing device. 6. Next, the mixture is sprayed and granulated using a spray dryer.

These granulated powders are put into a mold and molded, and in order to remove added water and organic binders, they are fired in air at 500°C and then pre-fired at 1050°C.

After that, a high-resistance material is applied and fired in air at 1200°C, color coating is performed, and color firing is performed. Furthermore, the open plane was polished and an aluminum metallicon electrode was attached to the open plane to obtain a nonlinear resistor with a diameter of 100 mm and a thickness of 22 mm.

As mentioned above, for the nonlinear resistor completed using nickel oxide with nine different particle radii, the voltage that shows nonlinearity -
As current characteristics, V1mA/V O, 1mA, V O
, 1mA/V 0.01mA are measured and the results are shown in Figure 1. When the particle radius is in the range of 0.2 to 1.5-, V 1
mA/VO, 1mA is 1.08 or less, VO, 1++
It is recognized that A/V 0.01mA is 1.16 or less, which is the best characteristic.

Furthermore, as a phenomenon of deterioration of the voltage-current characteristics due to surge, which is an important characteristic of non-linear resistors, the results were obtained before and after applying a 100 KA impulse three times in a row with a waveform of 4 umbrellas and 10 t1s to the nine types of completed non-linear resistors. Varistor voltage V1m
The rate of change in A is shown in Figure 2.

The particle radius with a change rate of 1% or less is 0.2 to 1.5. This is the most desirable rate of change for a nonlinear resistor.

As mentioned above, by using NiO with a particle radius of 0.2 to 1.5 μs as the nickel raw material, the voltage
The reason why the rate of change in VlmA due to current characteristics and impulse surge is the best is not clear, but it is thought to be as follows.

In other words, during the firing process, nickel oxide exists in the nonlinear resistor as a solid solution in and between zinc oxide particles together with many metal oxides, but in particular spinel particles between zinc oxide particles. (Zn, 5b2o1.') and bismuth oxide as the main components. This particle layer forms the Schottky barrier, which plays an important role in the voltage-current characteristics in the small current range, and the interface state, which is involved in the tunneling effect in the large current range, and plays an important role in nonlinear resistors. .

In order for nickel oxide to be induced by bismuth oxide, which becomes a liquid layer at high temperatures, to form a homogeneous grain boundary layer with cobalt oxide, manganese oxide, etc., it is necessary to be able to mix uniformly and to reduce reactivity during the firing process. If the particle radius of nickel oxide is less than 0.2, the cohesive force of the raw material itself will be strong, making it impossible to mix uniformly with zinc oxide and other raw materials, and coarse particles of 1.5 μs or more will When this happens, the particle radius becomes too large compared to the particle radius of the zinc oxide raw material, which is the main component, and the formation of a homogeneous grain boundary layer is inhibited.
6. Particle radius made by changing manufacturing conditions is 0.0, which is considered to deteriorate non-linear characteristics and durability against impulse surge.
7 Non-linear characteristics of a non-linear resistor made using nickel oxide of 5 to 5- and V 1 mA due to impulse surge
As shown in Figures 1 and 2, the rate of change is between 0.2 and 1.
．． The best value was obtained in the case of 5-. It has a remarkable effect when used as a lightning arrester.

In addition, in this experimental example, the shape of the non-linear resistor is φ100$22.
t, but it was confirmed that the same effect can be obtained with a smaller capacity one.

Furthermore, the effect of increasing the capacity of the nonlinear resistor is also obvious for the reasons described above.

〔Effect of the invention〕

As explained above, according to the present invention, nickel oxide (Nip
), it is possible to disperse homogeneously during mixing, and a sintered body with a homogeneous grain boundary layer is obtained during the firing process, resulting in good nonlinear characteristics in the micro current range and durability against impulse surges. It is possible to provide a method for manufacturing a non-linear resistor with strong resistance.

[Brief explanation of the drawing]

Figure 1 shows the voltage-current characteristics of a non-linear resistor using nickel oxide in which the particle radius of the nickel raw material is varied from 0.05 to 5/j11 as an example of the present invention.
mA/V O,1! IIA, V 0.1! ! 1A/V
A diagram showing 0.01 mA, and Figure 2 is a diagram showing the rate of change in V1+aA before and after applying a 100 KA impulse surge three times in a row with a 4 $10 μs waveform for a non-linear resistor manufactured in the same way. . Agent Patent Attorney Noriyuki Chika Yudo Ken Daishimaru

Claims (1)

[Claims] This mixture is produced by mixing zinc oxide as a main component, containing at least nickel as a subcomponent, bismuth oxide, antimony oxide, manganese oxide, chromium oxide, cobalt oxide, silicon dioxide, aluminum oxide, etc. with water and an organic binder. This is a non-linear resistor manufacturing method in which the granulated powder is molded, pre-fired, and then a high-resistance material is applied to the sides, fired, and metal electrodes are formed on both sides of the non-linear resistor. A method for manufacturing a nonlinear resistor, characterized in that the nickel inside is nickel oxide, and the particle radius is 0.2 to 1.5 μm.