JPH0812805B2 - 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) Conventionally, the main component is zinc oxide, and Bi ₂ O ₃ , Sb ₂ O ₃ , Si
It is widely known that resistors containing a small amount of additives such as O ₂ , Co ₂ O ₃ and MnO ₂ exhibit excellent voltage nonlinearity. ing.

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, there are α-type, β-type, γ-type δ-type bismuth phases, pyrochlore phase, etc. in addition to the zinc oxide crystal phase. However, depending on the amount ratio, the rate of change of V _1mA after applying a surge may be large, or
The rate of change of the −I characteristic with respect to temperature becomes large, and in any case, the characteristic with respect to multiple lightning may be deteriorated. In addition, when the change rate of V _1mA is large like this, the gapless lightning arrester has a risk of thermal runaway, and the lightning arrester with a gap may not be capable of interrupting 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 of the present invention contains zinc oxide as a main component,
In a voltage non-linear resistor containing a metal oxide such as bismuth oxide, antimony oxide, or silicon oxide as an additive component,
When the crystal phase of bismuth oxide includes at least three types of crystal phases of α-type, β-type, and δ-type, and the respective amounts of α-type, β-type, and δ-type crystals are α, β, and δ, It is characterized by satisfying the relationship of.

(Operation) In the above-described configuration, a voltage non-linear resistor in which the crystal phase of bismuth oxide in the resistor includes at least a predetermined amount ratio of α-type, β-type and δ-type crystal phases is clear from Examples described later. As described above, it was found that the rate of change of V _{1 mA} after the application of the surge was small and the rate of change of the VI characteristic with respect to temperature was 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, does not cause thermal runaway, and has a good life.

Here, explaining the effects of each phase, the δ phase is mainly
It has the effect of reducing the V _1mA change rate and also has the effect of improving the surge withstand capability. The α phase and the β phase mainly have an effect of reducing the rate of change of the VI characteristic with respect to temperature, and the effect is small and the life is deteriorated when the α phase or the β phase is used alone. If it is not within the range, the effect is small. In addition, the γ phase has a long life, but it adversely affects the other properties described above, so at most 0.5 wt%
The following is preferable. Further, it is preferable not to contain the pyrochlore phase.

In addition, a glass frit is used when manufacturing the resistor.
Add 0.01 to 0.3wt%. Alternatively, it is preferable to add silicon oxide in an amorphous state because the grain boundary layer is stabilized.

The relationship between the α-type, β-type and δ-type crystal amounts α, β and δ is 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.

After that, both end surfaces of the obtained voltage nonlinear resistor are
Polishing is carried out with water, preferably oil, as a polishing liquid with a polishing agent corresponding to # 400 to 2000 such as 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 various conditions such as the main firing conditions, the main firing cooling rate, and the heat treatment conditions after the main firing, the α-Bi ₂ O ₃ crystalline phase and the β-Bi ₂ O ₃ crystalline phase of at least a predetermined amount ratio in the sintered body can be obtained. And the voltage non-linear resistor of the present invention containing the δ-Bi ₂ O ₃ crystal phase can be produced, and a desired voltage non-linear resistor having a desired V _1mA change rate and a change rate of VI characteristic with respect to temperature can be obtained. Is what you get.

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} , NiO 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 1.0 to 3.0 mol%, balance ZnO
Sample Nos. 1 to 9 of the present invention and Comparative Example Sample No. 1 having a crystal phase shown in Table 1 having a diameter of 47 mm and a thickness of 22.5 mm and a varistor voltage (V _1mA ) of 200 to 230 V / mm. A voltage non-linear resistor of 1-10 was 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 for _1mA and V _40KA
Was calculated as the rate of change. Compared to 25 ℃ at 150 ℃, V _1mA
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. Lightning surge withstand current of 130KA and 150KA is 4/10
A sample which was destroyed after being applied twice with a current waveform of μs was marked with X, and a sample which was not broken was marked with ◯. The switching surge resistance is shown as × when the current of 800 A and 1000 A was repeatedly applied 20 times with the current waveform of 2 ms and was broken, and as ○ when it was not broken. 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 thermal runaway, and C is thermal runaway. 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 α-phase, β-phase and δ-phase has better temperature characteristics and V _1mA lowering rate than other Comparative Examples, and other It can be seen that various characteristics are also good.

The voltage application pattern of the present invention is not A (best), but there is no fear 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 α phase, β phase, and δ phase, so that V _{1 mA} change due to lightning surge application It is possible to obtain good characteristics against multiple lightning with a small rate and a small temperature change in voltage-current characteristics, and also to obtain other characteristics such as good surge withstand 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 containing zinc oxide as a main component and a metal oxide such as bismuth oxide, antimony oxide, or silicon oxide as an additional component, wherein the crystal phase of bismuth oxide is at least α-type or β-type, It contains three types of δ-type crystal phases, and α-type, β-type and δ-type crystal amounts are α,
Given β and δ, A voltage non-linear resistor characterized by satisfying the following relationship.