JPH06349608A - Screening of nonlinear resistor - Google Patents

Abstract

PURPOSE:To provide such a method of screening high-reliability and high- practicability nonlinear resistors as a nonlinear resistor having an energy absorption power, which is not met a constant level, is removed without reducing the energy absorption power of the nonlinear resistors, which are an object of screening, and the nonlinear resistors only having an energy absorption power of the constant level or higher can be selected reliably and easily. CONSTITUTION:A current of an energy remarkably lower than an energy absorption power necessary for nonlinear resistors, which are respectively formed with 2111 electrode, is made to flow through these nonlinear resistors. The temperature distribution of the resistors after the current is made to flow is measured and some one of such a plurality of parameters as a reference deviation of the temperature distribution, a ratio which is occupied by temperature of 80% or higher of the highest temperature, a reference deviation of a stress distribution and a ratio which is occupied by stresses of 80 % or higher of the largest stress is calculated on the basis of the measured result. Whether the calculated value satisfies a prescribed condition or not is decided and in the case where the condition is satisfied, the resistors having the condition are selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-linear resistor used in an overvoltage protection device for protecting an electric power system, and in particular, only supplies a non-linear resistor having a stable strength against overvoltage and a certain level or more. In order to do so, the present invention relates to a screening method for selecting only non-linear resistors having an energy absorption capacity of a certain level or higher.

[0002]

2. Description of the Related Art Generally, in a power system, an overvoltage protection device is used to remove an overvoltage superimposed on a normal voltage to protect the power system. In such an overvoltage protection device, a non-linear resistor is often used to fulfill its duty. That is,
This non-linear resistor is a resistor that has a substantially insulating property at a normal voltage and a relatively low resistance when an overvoltage is applied.

In order to improve the reliability of the overvoltage protection device, such a non-linear resistor has an energy absorption capacity above a certain level and is stable against overvoltage and has a strength above a certain level. Required to have.
However, since the non-linear resistor is generally a ceramic product manufactured by molding and firing raw material powder, it is unavoidable that the energy absorption capacity varies due to the variation in the production. Therefore, in such non-linear resistors of ceramic products, remove non-linear resistors whose energy absorption capacity does not reach a certain level and select only non-linear resistors whose energy absorption capacity is more than a certain level. is necessary.
Conventionally, as a screening method for such a non-linear resistor, an electric current having an extremely large energy, which is close to the required energy absorption capacity, is applied to the non-linear resistor once or several times in succession to destroy the non-linear resistor. Methods have been used to remove the linear resistor.

[0004]

However, in the conventional method for screening a non-linear resistor as described above,
There are the following problems. In other words, since a current with an extremely large energy, which is close to the required energy absorption capacity, is continuously flowed once or several times to all the non-linear resistors to be screened, the energy absorption capacity is constant. Not only is the non-linear resistor less than the level destroyed, but the non-linear resistor having an energy absorption capacity of a certain level or more is also seriously damaged. As a result, the energy absorption capacity of a non-linear resistor that originally had a high level of energy absorption above a certain level will be reduced by screening, and a non-linear resistor with a high energy absorption capacity will be supplied. It contradicts the original purpose of screening.

On the other hand, conventionally, a pulse current is passed through a non-linear resistor before electrode formation, the temperature distribution during this energization is measured, and the generated stress is calculated to obtain zinc oxide having a predetermined stress state. A screening method for selecting only non-linear resistors is known. When this screening method is adopted, an electrode is formed on the facing surface of the selected zinc oxide nonlinear resistor after this screening. However, this method has the following problems. That is, first, it is difficult to pass a pulse current through the nonlinear resistor before forming the electrodes. Further, in this conventional method, the predetermined stress state is not clearly grasped as a concrete numerical value, and since it is an incomplete method in that sense, its action and effect are unclear, and there is a problem in practicality. is there.

The present invention has been proposed in order to solve the above problems of the prior art, and its purpose is to:
Without reducing the energy absorption capacity of the non-linear resistor to be screened, remove the non-linear resistance element whose energy absorption capacity does not reach a certain level, and only use the non-linear resistance element having the energy absorption capacity above a certain level. It is an object of the present invention to provide a highly reliable and highly practical screening method for a non-linear resistor which can be reliably and easily selected.

[0007]

In the method for screening a non-linear resistor according to the present invention, an electrode is formed in the method for screening a non-linear resistor in which a non-linear resistor having an energy absorption capacity of a certain level or more is selected. Basically, there are an energization step of flowing a current having a set predetermined energy in the non-linear resistor, and a measurement step of measuring the temperature distribution of the electrode formation surface of the non-linear resistor after the energization step.

In the method according to claim 1, in addition to the energization step and the measurement step, a calculation step for calculating the standard deviation from the temperature distribution measured in the measurement step, and a calculation step in the calculation step A standard deviation of the temperature distribution is judged whether or not a predetermined condition set as a selection criterion is satisfied, and when the predetermined condition is satisfied, a selection step of selecting the non-linear resistor is included. Is characterized by.

According to a second aspect of the present invention, in addition to the energization step and the measurement step, a calculation step of calculating a ratio of 80% or more of the maximum temperature from the temperature distribution measured by the measurement step. And whether the ratio calculated by the calculation step satisfies a predetermined condition set as a selection criterion, and when the predetermined condition is satisfied, the selection of selecting the non-linear resistor And a step.

According to a third aspect of the present invention, in addition to the energizing step and the measuring step, a calculating step for calculating a standard deviation of a stress distribution generated from the temperature distribution measured by the measuring step, and the calculating step. The standard deviation of the stress distribution calculated by determines whether or not a predetermined condition set as a selection criterion is satisfied, and when the predetermined condition is satisfied, a selection step of selecting the non-linear resistor It is characterized by having and.

According to a fourth aspect of the invention, in addition to the energizing step and the measuring step, a first calculating step for calculating a stress distribution generated from the temperature distribution measured by the measuring step, and the first calculating step. A second calculation step of calculating a ratio of 80% or more of the maximum stress from the stress distribution calculated by the calculation step of
It is determined whether or not the ratio calculated by the second calculation step satisfies a predetermined condition set as a selection criterion, and when the predetermined condition is satisfied, the non-linear resistor is selected. And a selection step.

According to a fifth aspect of the present invention, in the method according to the first, second, third, or fourth aspect, in particular, the energizing step applies an AC short-circuit to the non-linear resistor. The method is characterized by including a step of applying a time overvoltage to cause a current to flow through the nonlinear resistor.

[0013]

The operation of the screening method of the present invention having the above-mentioned structure is as follows. First, the method of the present invention is based on the temperature distribution of a non-linear resistor formed with electrodes after energization, the standard deviation of the temperature distribution, the ratio of 80% or more of the maximum temperature to the temperature, the standard deviation of the stress distribution, This is a method of calculating one of a plurality of parameters, that is, a ratio of 80% or more of the maximum stress, and determining whether or not the calculated value satisfies a predetermined condition. Only non-linear resistors with energy absorption capability can be selected reliably and easily. That is, as shown in FIGS. 1 to 4, these parameters have a clear proportional or inversely proportional relationship with the energy absorption capacity of the nonlinear resistor. Therefore, by calculating the values of these parameters, the nonlinearity is calculated. The energy absorption capacity of the resistor can be predicted almost accurately. Therefore, by determining the calculated values of these parameters obtained from the temperature distribution of the non-linear resistor under appropriate conditions, it is possible to reliably and easily select the non-linear resistor having an energy absorption capacity above a certain level.

When an AC short-time overvoltage is applied to the non-linear resistor and a current is passed through the non-linear resistor,
During this energization, there is no possibility of damaging the non-linear resistor or its electrode, or deterioration of the temperature distribution measurement accuracy.
Further, since it is possible to energize with a small current value for a long time, it becomes easy to synchronize with the time for measuring the temperature distribution, so that more effective screening can be performed.

In particular, since the screening method of the present invention is a method for selecting a non-linear resistor based on the temperature distribution of the non-linear resistor after energization, the energy of the current flowing through the non-linear resistor is non-linear. It is sufficient that the resistor can be heated. That is, in the method of the present invention, the energy of the current passed through the non-linear resistor has the same level as the energy absorption capacity required for the non-linear resistor as in the method of removing the non-linear resistor by destruction by energization. It is not necessary to increase the temperature, and it is sufficient to heat the non-linear resistor to cause a temperature distribution in the non-linear resistor. Therefore, in the method of the present invention, a non-linear resistor can be screened by passing a current having a much lower energy than the energy absorption capacity required for the non-linear resistor through the non-linear resistor. It does not damage the non-linear resistor and reduce its energy absorption capacity.

As a screening method similar to the present invention, as described above, a pulse current is passed through the non-linear resistor before electrode formation, the temperature distribution during this energization is measured, and the stress generated is calculated. Although there is known a screening method for selecting only a zinc oxide nonlinear resistor having a predetermined stress state, it is difficult to apply a pulse current to the nonlinear resistor before forming an electrode. It is an incomplete method with low practicability, which has a problem and a predetermined stress state is not clearly understood as a concrete numerical value. That is, as in the present invention, the temperature distribution is measured by passing a current through the non-linear resistor after the electrode formation, and based on this temperature distribution, the standard deviation of the temperature distribution,
Conventionally, there is no method for calculating specific parameters such as a ratio of 80% or more of the maximum temperature, a standard deviation of stress distribution, and a ratio of 80% or more of the maximum stress.

[0017]

EXAMPLES An example of the screening method according to the present invention will be described below. That is, first, ten cylindrical non-linear resistors having a diameter of 100 mm and a thickness of 20 mm were prepared as screening samples. Next, a pulse current of 300 A was passed through these non-linear resistors, and the temperature distribution on the upper electrode surface immediately after energization was measured with an infrared radiation thermometer. Then, an AC overvoltage in which a current of about 100 A flows was applied to the non-linear resistor after the temperature distribution was measured in this way, and the amount of energy absorption absorbed until destruction was obtained.

After that, the standard deviation was calculated from the measured temperature distribution, and the relationship between the standard deviation of this temperature distribution and the energy absorption amount absorbed by the nonlinear resistor until the destruction was calculated. The results shown in are obtained. As shown in FIG. 1, it can be understood that the energy absorption amount decreases as the standard deviation of the temperature distribution increases, and therefore the energy absorption capacity decreases.

From the measured temperature distribution, the ratio of 80% or more of the maximum temperature was calculated, and the relationship between this ratio and the amount of energy absorbed by the non-linear resistor before the destruction was calculated. However, the results shown in FIG. 2 were obtained. As shown in this Figure 2, 80% of the maximum temperature
It can be seen that the energy absorption amount increases as the ratio occupied by the above temperature increases, and therefore the energy absorption capacity improves.

Furthermore, the standard deviation of the stress distribution generated from the measured temperature distribution was calculated, and the relationship between the standard deviation of this stress distribution and the energy absorption amount absorbed by the nonlinear resistor until failure was calculated. The results shown in FIG. 3 were obtained. As shown in FIG. 3, it can be seen that the energy absorption amount decreases as the standard deviation of the stress distribution increases, and therefore the energy absorption capacity decreases.

Further, the stress distribution generated from the measured temperature distribution is calculated, and the ratio of 80% or more of the maximum stress is calculated from this stress distribution.
When the relationship of the amount of energy absorbed by the non-linear resistor before the destruction was determined, the results shown in FIG. 4 were obtained. As shown in FIG. 4, it can be seen that the energy absorption amount decreases as the proportion of the temperature at which 80% or more of the maximum stress occupies increases, and therefore the energy absorption capacity decreases.

As described above, the standard deviation of the temperature distribution, the ratio of the temperature of 80% or more of the maximum temperature, the standard deviation of the stress distribution, and the ratio of the stress of 80% or more of the maximum stress are the respective parameters. , All
As shown in FIG. 4, since it has a clear proportional relationship or inverse proportional relationship with the energy absorption capacity of the non-linear resistor, it is possible to calculate the non-linear resistance by calculating one or more of these parameters. The energy absorption capacity of the body can be predicted almost accurately. Therefore, by determining the calculated values of these parameters obtained from the temperature distribution of the non-linear resistor by appropriate conditions,
It is possible to reliably and easily select a non-linear resistor having an energy absorption capacity above a certain level.

In this way, when the nonlinear resistor is selected based on the temperature distribution of the nonlinear resistor after energization,
The energy of the current flowing through the non-linear resistor is sufficient to heat the non-linear resistor, and the energy required for the non-linear resistor is the same as in the conventional method of removing the non-linear resistor by destruction by energization. The absorption capacity does not have to be as high as the absorption capacity, and it is sufficient to heat the non-linear resistor to generate a temperature distribution in the non-linear resistor. Specifically, although a pulse current of 300 A was passed in the above-mentioned embodiment, this is a current having a much lower energy than the energy absorption capacity required for the non-linear resistor, and therefore, as in the conventional method. Therefore, the non-linear resistor is not damaged and its energy absorbing ability is not lowered, and therefore, the high energy absorbing ability can be maintained.

By the way, when a pulse current is applied to the non-linear resistor as in the above embodiment, the non-linear resistor and the electrodes formed on the surface thereof may be damaged due to the large contact resistance between the electrodes. And the accuracy of temperature distribution measurement may be reduced by generating an arc when energized, and the energization time of the pulse current is extremely short, making it difficult to synchronize with the time of temperature distribution measurement. There are some problems such as On the other hand, instead of energizing the pulse current, by applying an AC short-time overvoltage to the non-linear resistor and causing a current to flow through the non-linear resistor, the problems due to the energization of the pulse current as described above are solved. More effective screening can be performed without occurring.

Actually, as another embodiment, instead of passing a pulse current, an AC short-time overvoltage is applied to the non-linear resistor to cause a current to flow through the non-linear resistor, and then the above-mentioned embodiment is used. Similarly, the temperature distribution is measured, and the standard deviation of the temperature distribution, the ratio of the temperature of 80% or more of the maximum temperature, the standard deviation of the stress distribution, and the ratio of the stress of 80% or more of the maximum stress are calculated, The relationship with the energy absorption capacity was investigated. As a result, also in this example, the relationships shown in FIGS. 1 to 4 were obtained as in the case of the above example. In particular, when an AC short-time overvoltage is applied to a non-linear resistor in this way, the possibility of damaging the non-linear resistor and its electrodes and the accuracy of temperature distribution measurement, as in the case of pulsed current, can be improved. There is no possibility of lowering the current, and since it is possible to energize with a current value smaller than the pulse current for a longer time than the pulse current, it is easier to synchronize with the time for measuring the temperature distribution, so it is more effective. Various screenings can be performed.

The present invention is not limited to the above-mentioned respective embodiments, and the current value to be passed through the non-linear resistor and the energizing time can be appropriately selected. In addition, the specific method of measuring the temperature distribution, the standard deviation of the temperature distribution, the maximum temperature of 80
A specific method for calculating parameters such as a percentage occupied by a temperature of not less than%, a standard deviation of stress distribution, a percentage occupied by a stress of not less than 80% of the maximum stress can be appropriately selected. Furthermore, the conditions for determining the calculated values of the respective parameters can be appropriately selected according to the energy absorption capacity required for the nonlinear resistor.

[0027]

As described above, in the method for screening a non-linear resistor according to the present invention, the standard deviation of the temperature distribution and the maximum temperature are determined based on the temperature distribution of the non-linear resistor formed with electrodes after energization. Of one of a plurality of parameters, that is, the ratio of 80% or more of temperature, the standard deviation of stress distribution, and the ratio of 80% or more of maximum stress, and the calculated value satisfies the specified condition. By determining whether or not to do so, the non-linear resistor whose energy absorption capacity does not reach a certain level is removed without lowering the energy absorption capacity of the non-linear resistance to be screened as in the conventional method. An excellent effect is obtained in that only a non-linear resistor having an energy absorption capacity above a certain level can be reliably and easily selected. Therefore, it is possible to perform screening with higher reliability and practicability than ever before.

[Brief description of drawings]

FIG. 1 is a diagram showing characteristics of a non-linear resistor obtained based on a temperature distribution measured after applying a predetermined current to the non-linear resistor according to the method for screening a non-linear resistor according to the present invention, In particular, a graph showing the relationship between the standard deviation of the temperature distribution and the amount of energy absorbed by the non-linear resistor before the destruction.

FIG. 2 is a diagram showing characteristics of a non-linear resistor obtained based on a temperature distribution measured after applying a predetermined current to the non-linear resistor according to the method for screening a non-linear resistor according to the present invention, Especially, the highest temperature of the temperature distribution is 8
The graph which shows the relationship of the ratio which the temperature of 0% or more occupies, and the energy absorption amount which the non-linear resistor absorbed until it reached destruction.

FIG. 3 is a diagram showing characteristics of a non-linear resistor obtained based on a temperature distribution measured after a predetermined current is applied to the non-linear resistor according to the method for screening a non-linear resistor according to the present invention, In particular, a graph showing the relationship between the standard deviation of the stress distribution calculated from the temperature distribution and the amount of energy absorbed by the non-linear resistor before the destruction.

FIG. 4 is a diagram showing characteristics of a non-linear resistor obtained based on a temperature distribution measured after applying a predetermined current to the non-linear resistor according to the method for screening a non-linear resistor according to the present invention; In particular, the ratio of 80% or more of the maximum stress in the stress distribution calculated from the temperature distribution,
The graph which shows the relationship of the energy absorption amount which the non-linear resistor absorbed before it was destroyed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Masawa No. 2 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Hamakawasaki Plant (72) Mitsuyuki Notsuki Ukishima, Kawasaki-ku, Kawasaki-shi, Kanagawa 2-1, Machi Co., Ltd. Inside the Toshiba Hamakawasaki factory

Claims (5)

[Claims] 1. A non-linear resistor screening method for selecting a non-linear resistor having an energy absorption capacity of a certain level or more, wherein a current having a set predetermined energy is applied to a non-linear resistor formed with electrodes. An energizing step of flowing, a measuring step of measuring the temperature distribution of the electrode forming surface of the non-linear resistor after the energizing step, a calculating step of calculating the standard deviation from the temperature distribution measured by the measuring step, It is determined whether or not the standard deviation of the temperature distribution calculated by the calculation step satisfies a predetermined condition set as a selection criterion, and if the predetermined condition is satisfied, the non-linear resistor is selected. And a screening step for a non-linear resistor. 2. A non-linear resistor screening method for selecting a non-linear resistor having an energy absorption capacity of a certain level or more, wherein a current having a set predetermined energy is applied to the non-linear resistor formed with electrodes. An energizing step of flowing, a measuring step of measuring the temperature distribution of the electrode forming surface of the non-linear resistor after the energizing step, and a temperature of 80% or more of the maximum temperature occupies from the temperature distribution measured by the measuring step. A calculation step of calculating a ratio, and the ratio calculated by the calculation step determines whether or not a predetermined condition set as a selection criterion is satisfied, and if the predetermined condition is satisfied, the non-linear And a step of selecting a resistor, the method for screening a non-linear resistor. 3. A non-linear resistor screening method for selecting a non-linear resistor having an energy absorption capacity of a certain level or more, wherein a current having a set predetermined energy is applied to the non-linear resistor formed with electrodes. An energizing step of flowing, a measuring step of measuring a temperature distribution of the electrode forming surface of the non-linear resistor after the energizing step, and a calculation of calculating a standard deviation of a stress distribution generated from the temperature distribution measured by the measuring step. Step, the standard deviation of the stress distribution calculated by the calculating step, it is determined whether or not to meet a predetermined condition set as a selection criterion, if the predetermined condition is satisfied, the nonlinear resistance And a step of selecting a body, the method for screening a non-linear resistor. 4. A non-linear resistor screening method for selecting a non-linear resistor having an energy absorption capacity of a certain level or higher, wherein a current having a set predetermined energy is applied to the non-linear resistor formed with electrodes. An energizing step of flowing, a measuring step of measuring a temperature distribution of the electrode formation surface of the non-linear resistor after the energizing step, and a first calculation of calculating a stress distribution generated from the temperature distribution measured by the measuring step. And a second calculation step of calculating a ratio of 80% or more of the maximum stress from the stress distribution calculated by the first calculation step, and a ratio calculated by the second calculation step. It is determined whether or not a predetermined condition set as a selection criterion is satisfied, and if the predetermined condition is satisfied, the non-linear resistance The screening method of the nonlinear resistor characterized by having a selection step of selecting. 5. The method according to claim 1, wherein the energizing step includes a step of applying an AC short-time overvoltage to the non-linear resistor to cause a current to flow through the non-linear resistor. The method for screening a non-linear resistor according to claim 3 or 4.