JPH0541302A - Bulk type of linear resistor and manufacture of same - Google Patents

Abstract

PURPOSE:To provide a bulk type of linear resistor and manufacture of the resistor whose resistance value little decreases up to 300 deg.C as a power resistor, and allowable temperature can be set higher than those for carbon resistors, and linearity on current and voltage characteristics is better than that for ZnO resistor, and electrical resistance is still more excellent than that of ZnO resistor. CONSTITUTION:A resistor comprises a sinter 1 which includes 5 to 40vol.% of metal boride and 60 to 95vol.% of non-reducing glass, and electrodes 2 and 2' which are provided on upper and lower sides of the sinter 1, characterized by a temperature coefficient of resistance value within a range of -1X10<-3> to +5X10<-3>/ deg.C at 300 deg.C of the sinter 1. Therefore, sizes of the resistors such as a closing resistor for a gas breader and a neutral resistor by application of this resistor can be considerably reduced as compared with sizes of conventional resistors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulk type linear resistor suitable for use in electric power equipment, particularly circuit breakers and transformers, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. Sho 56-56 has been used as a resistor.
A carbon type as described in Japanese Patent No. 4206 and a ZnO type as described in Japanese Patent Laid-Open No. 63-233502 are disclosed.

The carbon-based resistor has a structure in which carbon powder is dispersed in a matrix made of Al ₂ O ₃ , and its resistivity is several hundred Ωcm.

On the other hand, ZnO-based resistors have ZnO as a main component, and Al ₂ O ₃ , MgO, Y ₂ O ₃ , Sb ₂ O ₃ and SiO.
It is a crystal containing ₂ etc., and its resistivity is 10-100.
It is 0 Ωcm, and it is used properly depending on the applied device.

Then, the ZnO-based resistor is formed by mixing two or more kinds of raw material powders, adding an organic binder and granulating the powder. Then, after firing the molded body in an electric furnace,
The sintered body is sandwiched and the electrodes are arranged to face each other.

[0006] In addition to the above, those related to the resistor include, for example, Japanese Patent Publication Nos. 58-21402 and 5.
9-51721, Japanese Patent Publication No. 1-147802, Japanese Patent Publication No. 2-3524, and the like.

All of these relate to thick film compositions and have a structure in which electrically conductive LaB ₆ is dispersed in a matrix made of crystalline glass.

On the other hand, as a resistor for the thick film composition,
The ZrB ₂ system is disclosed in, for example, JP-A-62-2.
32901 can be mentioned.

The thick film composition contains an organic vehicle for screen printing together with a conductor paste on a substrate such as alumina.

By the way, the allowable temperature of the circuit board made of the thick film composition as described above is at most 150 ° C., and it is used for a power resistor which is heated to 200 ° C. or more because a large amount of energy is injected. Absent.

[0011]

A large amount of energy is injected into the power resistor during operation, and the power resistor has a temperature of 200 to 300 ° C.
Is heated up.

Therefore, in the high temperature range of 200 to 300 ° C., when the resistance value of the resistor is largely decreased, an excessive current flows, and when the resistor is destroyed, thermal runaway occurs.

Since the temperature coefficient of the resistance value of the carbon-based resistor is negative, it is necessary to set the allowable temperature to a low value.

On the other hand, the ZnO-based resistor has a problem that the current-voltage characteristic is poor.

Further, the thick film composition is applied to a thick film resistor as its name suggests, and is not considered as a resistor having a high energy capacity.

The object of the present invention is to provide a power resistor 30
The resistance value hardly decreases up to 0 ° C, the allowable temperature can be set higher than that of the carbon type, the linearity of the current-voltage characteristic is superior to that of the ZnO type, and the withstand current is more excellent than that of the ZnO type. An object of the present invention is to provide a remarkably excellent bulk type linear resistor and a manufacturing method thereof.

[0017]

A bulk type linear resistor according to the present invention comprises 5 to 40% by volume of metal boride and 60% by volume.
˜95% by volume of a non-reducing glass sintered body, and electrodes sandwiched by the sintered body and facing each other,
The temperature coefficient of resistance of the sintered body at a temperature of 300 ° C. is −1.
It is characterized in that it is in the range of × 10 ³ to +5 × 10 ³ / ° C.

The non-reducing glass, whose main component is an oxide, is a glass which is not reduced by heating in a reducing or inert gas such as nitrogen or argon. Therefore, the non-reducing glass is Is used when firing in a reducing or inert gas atmosphere.

The bulk type linear resistor, which is the object of the present invention, is a bulk linear resistor which is distinguished from the thick film type linear resistor and which is fired after molding.

Further, as described above, the power resistor in which the bulk type linear resistor of the present invention is used is heated to 200 to 300 ° C. by being injected with a large amount of energy during operation. However, since an electrical connection part and an insulator are provided in the tank that stores the bulk type linear resistor,
It is not allowed to raise the temperature above this temperature. From the above, in the present invention, the temperature coefficient of the resistance value of the sintered body is defined as described above with the temperature of 300 ° C. being the upper limit.

The allowable temperature of the circuit board made of the thick film composition is 150 ° C. at the most, and it is not used as a power resistor which is heated to 200 ° C. or more because a large amount of energy is injected. As mentioned above.

Metal borides include MoB, ZrB ₂ , T
iB ₂ , VB ₂ , NbB ₂ , TaB ₂ , CrB ₂ , LaB ₆ ,
Electrically conductive particles such as CaB ₆ and W ₂ B ₅ , especially L
The current-voltage characteristics of the aB ₆ system are excellent.

On the other hand, the method of manufacturing a bulk type linear resistor according to the present invention comprises 5 to 40% by volume of metal boride and 60 to 60% by volume.
An organic binder was added to a mixed powder consisting of 95% by volume of non-reducing glass, granulated and molded, and the mixture was fired in a nitrogen atmosphere, and then the sintered body was sandwiched and electrodes were arranged to face each other. The temperature coefficient of resistance at a body temperature of 300 ° C is -1 x 1
It is characterized in that it is set in the range of 0 to ³ to + 5 × 10 ³ / ° C.

The metal boride is an electrically conductive powder of each of the above-listed materials such as MoB, and it has been described above that the LaB ₆ system has excellent current-voltage characteristics.

The metal boride is 5 to 40% by volume.
Is an appropriate amount. Below 5% by volume, the resistivity is 5000Ω
It becomes more than cm and is not suitable for electric power equipment. On the other hand, 40
If it is more than volume%, the resistivity becomes 10 Ωcm or less, which is not suitable for electric power equipment.

As the non-reducing glass, borosilicate glass is suitable. The glass component appropriately contains Al ₂ O ₃ , ZrO ₂ , CaO, etc. in addition to SiO ₂ and B ₂ O ₃ .

The resistivity of the resistor also depends on the particle size of the metal boride. The larger the particle size, the higher the resistivity.

Incidentally, this point will be described in an embodiment.

The temperature coefficient of resistance of the bulk linear resistor of the present invention is -1 × 10 ³ to + 5 × at a temperature of 300 ° C.
It was confirmed by experiments that the range of 10 to ³ / ° C. was achieved and that the resistance value hardly decreased even at a high temperature of 300 ° C.

On the other hand, the current-voltage characteristic of the resistor of the present invention is Z
It was also confirmed by experiments that the linearity is superior to that of the nO system.

Note that these two points will also be described in the examples as in the case of the above-mentioned description of the resistivity.

For the neutral point grounding resistor and the circuit breaker resistor of the transformer, there is a test in which a current of several tens to several hundreds of amperes is applied for several seconds to several tens of seconds, but the bulk type linear resistor of the present invention is used. It was confirmed by experiment that the power consumption of 1 kW or more was normally performed by clearing this test.

That is, in the test, the temperature of the resistor rises to several hundreds of degrees Celsius, but the bulk type linear resistor of the present invention has the temperature upper limit value of 300 ° C. as the above-mentioned power resistor. It was confirmed by experiments that the function was maintained normally and the thermal runaway did not occur even if the temperature was raised to.

The firing temperature of the sintered body is preferably in the range of 500 ° C. to the glass softening point. If the temperature is 500 ° C. or lower, the shrinkage ratio does not increase. On the other hand, if the glass softening point or higher, the sintered body is deformed, which is not desirable.

It should be noted that the above-mentioned five prior art examples relating to thick film compositions specify that those thick film compositions are applied to thick film resistors, and the conditions of use are as follows:
The operating temperature is 100 ° C or lower.

On the other hand, the bulk type linear resistor of the present invention makes it possible to raise the permissible temperature of the power resistor to 300 ° C., as is clear from the above description and the description of the following examples. It is possible to consume electric power of 1 kW or more.

[0037]

The metal boride has a structure in which it is dispersed in a matrix made of non-reducing glass.

The metal boride is a conductive particle having a positive temperature coefficient of resistance and forms a conductive path, and the glass matrix functions as a resistance.
According to the present invention, the amount of the metal boride and the mixing ratio of the non-reducing glass are set as described above, and the temperature coefficient of the resistance value of the sintered body obtained by firing this is also within the above range. According to the experiment, the allowable temperature of the bulk type linear resistor as the power resistor thus obtained can be increased up to 300 ° C., and it is 10 to 5000 Ωcm suitable for the power equipment. Resistivity can be achieved.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an embodiment (cylindrical metal boride-based resistor) of a bulk linear resistor according to the present invention. ,
In the figure, 1 is a metal boride-based sintered body, and aluminum electrodes 2, 2'are provided on both surfaces of the metal boride-based sintered body 1.
Is attached.

FIG. 2 is a front view showing another embodiment (doughnut type metal boride type resistor) of the bulk type linear resistor according to the present invention. In FIG. 2, 3 is a metal boride type sintered body. , 4, 4 ′ are aluminum electrodes, but a hole 5 is provided at the center of the resistor.

Now, experimental examples of the present invention will be described below.

[Experimental Example 1] LaB ₆ : 158 g (9.4 g)
%), And glass frit: 842 g (90.6
(Volume%) was mixed with a lightning striker.

For LaB ₆ , powder having a particle size of 1 μm and powder having a particle size of 10 μm were used, and for the glass frit, La was used.
A borosilicate glass having the same density as B ₆ was used, and 30 cc of an aqueous polyvinyl alcohol solution was added thereto to granulate, followed by molding with a mold having a diameter of 105 mm to a thickness of 30 mm.

Next, the molded body was placed in an electric furnace and baked at a temperature of 700 ° C. in a nitrogen atmosphere for 4 hours.

Finally, aluminum was sprayed on both surfaces of this sintered body.

The resistor thus formed had a diameter of 95 mm and a thickness of 25 mm.

The resistance value of the resistor using LaB ₆ having a particle size of 1 μm is 15Ω (410Ωcm), while the particle size is 10
The resistance value of the resistor using LaB ₆ of μm was 3 MΩ.

[Experimental Example 2] LaB ₆ : 166 g (9.9)
%), And borosilicate glass: 834 g (90.
1% by volume) was mixed with a lightning striker, and an aqueous polyvinyl alcohol solution was added thereto, and the mixture was granulated and then molded.

Next, the molded body was placed in an electric furnace and baked in a nitrogen atmosphere at a constant temperature of 600 ° C. for 2 hours.

The resistance value of the resistor thus obtained was 11Ω.

On the other hand, ZrB ₂ : 292 g (15% by volume) and borosilicate glass: 707 g (85% by volume) were mixed by a lightning machine, and a polyvinyl alcohol aqueous solution was added thereto, and the mixture was granulated and then molded.

Then, the molded body was placed in an electric furnace and baked at a constant temperature of 900 ° C. in a nitrogen atmosphere for 2 hours.

The resistance value of the thus obtained resistor was 10.7Ω.

FIG. 3 is a current density-electrical resistance comparison characteristic diagram of the resistor of the present invention and the conventional resistor.

In FIG. 3, 6 is the characteristic curve of the LaB ₆ series resistor, 7 is the characteristic curve of the ZrB ₂ series resistor, 8 is the characteristic curve of the conventional ZnO series resistor, and 9 is the conventional carbon series resistor. As is clear from the figure, the linearity of the LaB ₆ series resistor 6 and the ZrB ₂ series resistor 7 is ZnO.
It is superior to that of the system resistor 8 and can obtain linearity equivalent to that of the carbon resistor 9.

FIG. 4 is a temperature-electric resistance comparison characteristic diagram of the resistor of the present invention and the conventional resistor.

In FIG. 4, 6'is the characteristic curve of the LaB ₆ series resistor, 7'is the characteristic curve of the ZrB ₂ series resistor, 8'is the characteristic curve of the conventional ZnO series resistor, and 9'is the conventional carbon. It is a characteristic curve of the system resistor, and as is clear from the figure, L
The temperature characteristics of the aB ₆ series resistor 6 ′ and the ZrB ₂ series resistor 7 ′ at the time of temperature rise are superior to those of the carbon series resistor 9 ′,
Temperature characteristics similar to those of the ZnO-based resistor 8'are obtained.

Table 1 shows the withstand currents of the resistor of the present invention and the conventional ZnO-based resistor.

[0059]

[Table 1]

The energization resistance is to check whether the resistor is normal when an alternating current of a dozen A is applied for a certain period of time or whether the resistor is broken.

Table 1 shows the time required for each sample to be energized for a long time and to cause a rapid increase in current, thermal runaway, breakdown, etc. of each sample.

The energizing current in Table 1 indicates the initial current at the start of the test, and this value changes during energizing.

Further, the electric power in Table 1 also shows the value at the start of the test, and the temperature of the sample is finally raised to 200 to 300 ° C.

From Table 1, LaB ₆ series resistors and ZrB ₂
It can be seen that the energization time of the system resistor is more than twice as long as that of the ZnO system resistor, and the energization resistance of the resistor of the present invention is remarkably superior to the conventional one.

[Experimental Example 3] FIG. 5 is an explanatory diagram of the internal structure when the bulk type linear resistor (donut type metal boride type resistor) shown in FIG. 2 is applied to a closing resistor for a gas circuit breaker (GCB). Is.

The resistor having a resistivity of 100 Ωcm manufactured in the process of Experimental Example 1 was applied to the closing resistor for gas circuit breaker shown in FIG. And, the content of LaB ₆ is 1
It was 7.6% by volume.

In the figure, 10 is a resistor, 11 is a bushing,
12 is an insulating rod, 13 is a capacitor, 14 is a blocking part,
15 is an oil dashpot, 16 is an opening / closing piston,
17 is an air tank.

The energization resistance of the closing resistor for gas circuit breaker to which the bulk type linear resistor of the present invention is applied is very large, and the linearity of the resistance value and the temperature characteristic are excellent. Compared with the conventional gas circuit breaker, the size and weight of the device can be reduced and the number of resistors used can be reduced for the following reasons.

That is, the reason for this will be explained using the numerical values shown in the above experimental example. The resistance of the present invention resistor (bulk type linear resistor) shown in the previous experimental example is equal to that of the conventional resistor. Since it is twice as large as the
2 can be reduced, and the resistance value in the high current range is 10
%, The number of resistors can be reduced by 10%, and the resistance value at a high temperature is increased by 20%. In this respect also, the number of resistors can be reduced by 20%.

[Experimental Example 4] FIG. 6 shows a case where the bulk type linear resistor (doughnut type metal boride type resistor) shown in FIG. 2 is applied to an SF ₆ gas insulated neutral point grounding resistor (NGR) for a transformer. It is an internal structure explanatory view of.

The neutral point grounding resistor shown in FIG.
A resistor having a resistivity of 410 Ωcm manufactured in the process of Experimental Example 1 was applied.

In the figure, 10 is a resistor, 12 'is an insulating rod, 17 is a bushing, 18 is a tank, and 19 is a ground point.

The neutral resistance of the neutral point grounding resistor to which the bulk type linear resistor of the present invention is applied is extremely large as is the case with the closing resistor for the gas circuit breaker, and the linearity of the resistance value and the temperature. The characteristics are also excellent, and the size and weight of the device can be reduced and the number of resistors used can be reduced as compared with a transformer using a conventional resistor.

[0074]

The present invention is as described above. According to the present invention, the permissible temperature is set to be higher than that of the carbon type, with the resistance value hardly decreasing up to 300 ° C. as a power resistor. And the linearity of the current-voltage characteristic is Z
It is superior to nO type and has much higher current carrying capability than ZnO system, and it is superior to conventional resistors in terms of temperature characteristics, current-voltage characteristics and current handling capability. You can play.

Further, according to the present invention, the size of the closing resistor for gas circuit breaker and the neutral grounding resistor to which the resistor is applied is reduced to 40% or less as compared with that of the conventional resistor. can do.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment (cylindrical metal boride-based resistor) of a bulk linear resistor according to the present invention.

FIG. 2 is a front view showing another embodiment (a toroidal metal boride-based resistor) of the bulk linear resistor according to the present invention.

FIG. 3 is a current density-electrical resistance comparison characteristic diagram of a resistor of the present invention and a conventional resistor.

FIG. 4 is a temperature-electrical resistance comparison characteristic diagram of a resistor of the present invention and a conventional resistor.

5 is an explanatory diagram of the internal structure when the bulk type linear resistor (donut type metal boride type resistor) shown in FIG. 2 is applied to a closing resistor for a gas circuit breaker (GCB).

FIG. 6 is an explanatory diagram of the internal structure when the bulk type linear resistor (donut type metal boride type resistor) shown in FIG. 2 is applied to an SF ₆ gas insulated neutral point grounding resistor (NGR) for a transformer. ..

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal boride-based sintered body, 2, 2 '... Aluminum electrode, 3 ... Metal boride-based sintered body, 4, 4' ... Aluminum electrode, 5 ... Hole, 6, 6 '... LaB ₆ series resistor Characteristic curve, 7, 7 '... Characteristic curve of ZrB ₂ system resistor, 8, 8'
... Characteristic curve of conventional ZnO-based resistor, 9, 9 '... Characteristic curve of conventional carbon-based resistor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadamichi Asai 4026 Kujimachi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Takeo Yamazaki 1-1-1 Kokubuncho, Hitachi City, Ibaraki Stock Hitachi, Ltd. Kokubu factory

Claims (8)

[Claims] 1. A metal boride of 5 to 40% by volume and 60.
˜95% by volume of a non-reducing glass sintered body, and electrodes sandwiched by the sintered body and facing each other,
The temperature coefficient of resistance of the sintered body at a temperature of 300 ° C. is −1.
A bulk type linear resistor having a range of × 10 ³ to +5 × 10 ³ / ° C. 2. The metal boride according to claim 1, wherein the metal boride is Mo.
B, ZrB ₂ , TiB ₂ , VB ₂ , NbB ₂ , TaB ₂ , C
A bulk type linear resistor which is one or more kinds of particles selected from rB ₂ , LaB ₆ , CaB ₆ and W ₂ B ₅ . 3. The metal boride according to claim 1, wherein the metal boride is La.
A bulk type linear resistor which is 5 to 40% by volume of lanthanum boride in terms of B ₆ . 4. A gas circuit breaker including a breaker housed in a tank and a closing resistor, wherein the resistor has 5 to 40 parts.
The sintered body is composed of a metal boride of volume% and a non-reducing glass of 60 to 95 volume%, and electrodes which are arranged to face each other with the sintered body interposed therebetween, and the temperature of the sintered body is 30.
Temperature coefficient of resistance at 0 ° C is -1 x 10 to ³ to +5 x 10
A gas circuit breaker characterized by using a bulk type linear resistor having a temperature range of up to ³ ° C. 5. A neutral grounding resistor including a resistor housed in a tank, wherein the resistor comprises 5-40 vol% metal boride and 60-95 vol% non-reducing glass. And a pair of electrodes that are arranged to face each other across the sintered body, and the temperature coefficient of the resistance value of the sintered body at a temperature of 300 ° C. is −1 × 10 to ³ to + 5 × 10 to Neutral point grounding resistor characterized by using a bulk type linear resistor in the range of ³ / ° C. 6. A metal boride of 5 to 40% by volume, and 60 to
An organic binder was added to a mixed powder consisting of 95% by volume of non-reducing glass, granulated and molded, and the mixture was fired in a nitrogen atmosphere, and then the sintered body was sandwiched and electrodes were arranged to face each other. The temperature coefficient of resistance at a body temperature of 300 ° C is -1 x 1
A method of manufacturing a bulk type linear resistor, characterized in that the range is 0 to ³ to + 5 × 10 ³ / ° C. 7. The metal boride according to claim 6, wherein the metal boride is Mo.
B, ZrB ₂ , TiB ₂ , VB ₂ , NbB ₂ , TaB ₂ , C
A method for producing a bulk linear resistor, which is one or more powders selected from rB ₂ , LaB ₆ , CaB ₆ , and W ₂ B ₅ . 8. The metal boride according to claim 6, which is La.
A method for manufacturing a bulk linear resistor, which is 5 to 40 vol% lanthanum boride in terms of B ₆ .