JPH0812806B2 - Voltage nonlinear resistor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a voltage non-linear resistor mainly composed of zinc oxide.

(Prior art) Bi ₂ O ₃ , Sb ₂ O ₃ , SiO ₂ , mainly containing zinc oxide,
It is widely known that a resistor containing a small amount of additives such as Co ₂ O ₃ and MnO ₂ exhibits excellent voltage non-linearity, and the property is used for a lightning arrester and the like.

Especially when used as a lightning arrester, even if an excessive current flows due to a lightning strike, the current is normally an insulator and is grounded by a voltage non-linear resistor that becomes a conductor when a voltage greater than a specified voltage is applied. , It is possible to prevent accidents caused by lightning strikes.

(Problems to be solved by the invention) As the crystal phase of this voltage nonlinear resistor, in addition to the crystal phase of zinc oxide, α-type, β-type, γ-type, δ-type bismuth layers, pyrochlore phase, and the like are used as grain boundary layers. Although there exist, depending on the amount ratio, the rate of change of V _1mA after surge application becomes large,
The rate of change of the VI characteristic with respect to temperature increases, and in any case, the characteristic with respect to multiple lightning may deteriorate. In addition, when the rate of change of V _1mA is large, there is a risk of thermal runaway in the gapless arrester, and there is a problem that the surge arrester with a gap becomes unable to interrupt the follow current.

An object of the present invention is to solve the above-mentioned problems and to provide a voltage non-linear resistor that exhibits good characteristics even against multiple lightning strikes.

(Means for Solving the Problems) The voltage nonlinear resistor according to the present invention is a voltage nonlinear resistor containing zinc oxide as a main component and a metal oxide such as bismuth oxide, antimony oxide, or silicon oxide as an additive component. , The crystal phase of bismuth oxide is at least β-type and δ-type 2
When including β type and δ type crystal amounts with β and δ, It is characterized by satisfying the relationship of.

(Operation) In the above-mentioned configuration, the voltage nonlinear resistor in which the crystal phase of bismuth oxide in the resistor includes at least a predetermined amount ratio β-type and δ-type crystal phase, as is clear from Examples described later, This is due to the fact that the rate of change of V _{1 mA} after application of a surge is small and the rate of change of the VI characteristic with respect to temperature is small. As a result, it is possible to obtain a voltage non-linear resistor which has a good surge withstand capability, is good against multiple lightning, and is free from thermal runaway and has a good life.

Explaining the effect of each phase, the δ phase mainly has an effect of reducing the V _1mA change rate after application of a lightning surge and also has an effect of improving the surge withstand capability. The β phase mainly has an effect of reducing the rate of change of the VI characteristic with respect to temperature, and the effect can be further improved by coexisting with the δ phase. However, if the β phase alone is used, the life is deteriorated, which is not preferable. Further, the γ phase has a favorable life, but adversely affects the other characteristics described above, so that it is preferably 0.5 wt% or less at most. Further, it is preferable not to contain the pyrochlore phase.

Furthermore, 0.01 to 0.3 wt% glass frit is used during the manufacturing process.
Added. Further, it is preferable to add silicon oxide in an amorphous state because the grain boundary layer is stabilized.

Note that the relationship between β and δ is 70 ≦ β / (β + δ) × 100 ≦ 80
It is preferable that it is because the effect of the present invention becomes more remarkable.

(Example) In order to obtain a voltage nonlinear resistor containing zinc oxide as a main component, first, a zinc oxide raw material adjusted to a predetermined particle size and bismuth oxide, cobalt oxide, manganese oxide, antimony oxide adjusted to a predetermined particle size, A predetermined amount of an additive made of chromium oxide, preferably amorphous silicon oxide, nickel oxide, boron oxide, silver oxide or the like is mixed. In this case, silver nitrate or boric acid may be used instead of silver oxide or boron oxide. Bismuth borosilicate glass containing silver is preferably used. At this time, a predetermined amount of polyvinyl alcohol aqueous solution or the like is added to these raw material powders. Further, preferably, a predetermined amount of aluminum nitrate solution is added as a source of aluminum oxide. This mixing operation preferably uses an emulsifier.

Next, vacuum degassing is preferably performed at a vacuum degree of 200 mmHg or less to obtain a mixed sludge. The water content of the mixed slurry is 30-35 wt.
%, And the viscosity of the mixed slurry is preferably 100 ± 50 cp. Next, the obtained mixed sludge is supplied to a spray dryer to have an average particle size of 50 to 150 μm, preferably 80 to 120 μm.
And the water content is 0.5 to 2.0 wt%, more preferably 0.9 to 1.5 wt
Granulate% granulated powder. Next, the obtained granulated powder is molded into a predetermined shape under a molding pressure of 800 to 1000 kg / cm ^{2 in} a molding step. Then, the molded body is heated / cooled at a temperature of 50 to 70 ° C.
Firing is performed under the conditions of 800 to 1000 ° C./hr and a holding time of 1 to 5 hours. In addition, the temperature rising / falling rate of the molded body is 10 to 10 before the calcination.
It is preferable to remove the binder by scattering at 400 to 600 ° C. at 0 ° C./hr and a holding time of 1 to 10 hours.

Next, an insulating coating layer is formed on the side surface of the calcined body that has been calcined. In the present invention, an oxide paste obtained by adding ethyl cellulose, butyl carbitol, n-butyl acetate or the like as an organic binder to a predetermined amount of Bi ₂ O ₃ , Sb ₂ O ₃ , ZnO, SiO ₂ or the like is used.
Apply to the side of the calcined body to a thickness of 300 μm. Next, the temperature rising / falling rate is 20 to 60 ° C / hr, 1000 to 1300 ° C, preferably 110
The main firing is performed under the conditions of 0 to 1250 ° C. and 3 to 7 hours. Incidentally, ethyl cellulose as an organic binder in glass powder,
A glass paste containing butyl carbitol, n-butyl acetate, etc. is applied on the above-mentioned insulating coating layer to a thickness of 100 to 300 μm, and the temperature rising and falling speed is 50 to 200 ° C./hr and 400 to 900 ° C. holding time. It is preferable to form the glass layer by heat treatment under the condition of 0.5 to 2 hours.

Then, remove both ends of the obtained voltage nonlinear resistor from the SiC,
Polishing is carried out using water, preferably oil, as a polishing liquid with a polishing agent corresponding to # 400 to 2000 such as Al ₂ O ₃ and diamond. Next, after cleaning the polished surface, electrodes are provided, for example, by spraying, on the polished both end surfaces by, for example, aluminum or the like to obtain a voltage non-linear resistor.

In the manufacturing method described above, the kind and addition amount of raw materials,
By combining the main calcination conditions, the main calcination cooling rate, and the heat treatment conditions after the main calcination, at least a predetermined amount of β-Bi ₂ O ₃ crystal phase and δ-Bi ₂ O ₃ crystal phase in the sintered body can be obtained. It is possible to manufacture the voltage non-linear resistor of the present invention including the target V
It is possible to obtain a good voltage non-linear resistor having a change rate of _{1 mA and a} change rate of VI characteristics with respect to temperature.

Hereinafter, the results of actually measuring various characteristics of the voltage nonlinear resistor within and outside the range of the present invention will be described.

Examples Bi ₂ O ₃ , Co ₃ O ₄ , MnO ₂ , Sb were prepared according to the method described above.
_{2 O 3, Cr 2 O 3} , each 0.1 to 2.0 _{mol%, Al (NO 3) 3} · 9H 2 O
0.001 to 0.01 mol%, bismuth borosilicate glass containing silver 0.01 to 0.3 wt%, amorphous SiO ₂ 0.5 to 3.0 mol%, balance Z
The first with a diameter of 47 mm and a thickness of 22.5 mm from the raw material consisting of nO
The voltage nonlinear resistors of the present invention samples No. 1 to 7 and the comparative example samples No. 1 to 3 having the crystal phases shown in the table were prepared.

With respect to the prepared resistors of the present invention and the comparative example, the temperature characteristics, V _1mA reduction rate, lightning surge withstand capability and switching surge withstand capability were measured, and the voltage application life pattern was determined. The results are shown in Table 1. Here, the temperature characteristic is V at 25 ° C.
V _1mA and V _{40kA at} 150 ° C _{vs 1mA} and V _40kA
Was calculated as the rate of change. V _1mA at 150 ° C compared to 25 ° C
Decreases and V _40kA increases. The V _1mA decrease rate was obtained from V _1mA before and after applying a current of 30 kA with a current waveform of 8/20 μs 10 times. The lightning surge withstand capability is indicated by X when the current of 130 kA and 150 kA was repeatedly applied twice with a current waveform of 4/10 μs and then destroyed, and as O when not destroyed. The switching surge withstand current is 800A and 1000A with a current waveform of 2ms.
After repeated application, the sample which was destroyed was indicated as X, and the one which was not destroyed was indicated as O. Further, the voltage application pattern was obtained from the relationship between the leakage current and time in FIG. In FIG. 1: A is the best one, B is good because it returns without running out of control, and C is thermal runaway. In addition,
The amount of each crystal phase was determined by the internal standard method by X-ray diffraction.

From the results shown in Table 1, the resistor of the present invention containing at least a predetermined amount ratio of β phase and δ phase has good temperature characteristics and V _1mA reduction rate as well as other characteristics as compared with Comparative Example. I understand.

Although the voltage application life pattern of the present invention is not A, there is no risk of thermal runaway. In the arrester with a gap, the element is not always charged, and B does not pose any problem.

(Effects of the Invention) As is clear from the above description, the voltage nonlinear resistor of the present invention contains at least a predetermined amount ratio of β phase and δ phase, so that the change in V _1mA due to lightning surge application is small. It is possible to obtain good characteristics against multiple lightning with a small temperature change of the voltage-current characteristics, and also to obtain other characteristics such as good surge withstanding capability and life.

[Brief description of drawings]

FIG. 1 is a graph showing a charging pattern as a relationship between leakage current and time.

Claims (1)

[Claims] 1. A voltage non-linear resistor comprising zinc oxide as a main component and a metal oxide such as bismuth oxide, antimony oxide or silicon oxide as an additive component, wherein the crystal phase of bismuth oxide is at least β type or δ type. When two types of crystal phases are included and β-type and δ-type crystal amounts are β and δ, respectively, A voltage non-linear resistor characterized by satisfying the following relationship.