JP2011202956A - Failure determination method of lightning arrester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure determination method for accurately determining the failure of partial destruction without disabling non-defective products in a device where pieces of equipment including a dynamic current cut-off function are connected in series.SOLUTION: The failure determination method of a lightning arrester goes through steps of: applying an input signal from less than approximately 1 kHz to more than approximately 1 MHz, and leading impedance of a sample lightning arrester from output signals of an earth-side terminal voltage Vin and a line-side terminal voltage Vout; leading a phase difference between the earth-side terminal voltage Vin and the line-side terminal voltage Vout; leading a serial component resistance value; obtaining a frequency characteristic curve peculiar to the sample lightning arrester by plotting the led serial component resistance value at log-log axes; and determining a case where a deviation of not less than a set amount is recognized in a frequency characteristic curve peculiar to the sample arrester and in the frequency characteristic curve of a non-defective arrester, and the deviation is confirmed at not more than 1 kHz and a case where the deviation is not confirmed at not more than 1 kHz and is recognized at not less than 100 kHz.

Description

  The present invention relates to a lightning arrester used for electric power equipment, and more particularly to maintenance / maintenance technology in a lightning arrester in which a plurality of zinc oxide elements having a continuity blocking function are connected in series.

Multiple elements of a lightning arrester are not all damaged at the same time by lightning strikes, so there are many cases where lightning strikes do not result in complete destruction (all element destruction) but partial destruction (partial element damage). .
Since the lightning arrester that has been partially destroyed does not have the performance at the time of introduction, the reliability of the power equipment is reduced.

One conventional method for determining a failure is to measure the insulation resistance.
The method of measuring the insulation resistance can be determined only when everything is completely damaged.
Therefore, disassembling work is required to determine the state of partial destruction, and a great deal of labor is required to implement all lightning arresters. In addition, when the state of partial destruction is determined, even if it is a normal product, it cannot be used again, and as a result, the lightning arrester must be replaced.
As described above, the partial failure state cannot be determined by the failure determination method.

  On the other hand, there is a method for measuring the current flowing through the lightning arrester (see the following patent document, for example), but there is not always a large difference between the partially destroyed product and the normal product, and the failure is detected accurately. It will not be possible.

JP-A-5-159909

  The present invention has been made in view of the above circumstances, and in a device in which devices having a continuity blocking function are connected in series, it is possible to accurately perform failure determination of partial destruction without disabling normal products. The purpose is to provide a possible failure determination method.

  A lightning arrester failure determination method according to the present invention made to solve the above-mentioned problems is achieved by connecting a signal source to the ground-side terminal and the line-side terminal of the sample lightning arrester and inputting an input frequency from less than about 1 kHz to more than about 1 MHz. A signal is applied, and an output signal obtained thereby is digitized, converted into a characteristic curve, and used for determination.

により試料避雷装置のインピーダンスを導くステップと、

により試料避雷装置のアース側端子電圧Ｖinとライン側端子電圧Ｖout間の位相差を導くステップと、

により試料避雷装置の直列成分抵抗値を導くステップと、
導かれた直列成分抵抗値を約１ｋＨｚ未満から約１ＭＨｚを超える周波数に至るまで両対数軸にプロットし試料避雷装置固有の周波数特性カーブを得るステップと、
試料避雷装置固有の周波数特性カーブと正常品避雷装置の周波数特性カーブに設定量以上の偏差が認められ、且つ
その偏差が１ｋＨｚ以下で確認された場合には完全破壊品と判定する一方、
その偏差が１ｋＨｚ以下で確認されず、且つ１００ｋＨｚ以上で確認された場合には部分破壊品と判定するステップとを経ることを特徴とする。 That is, from the output signals of the ground side terminal voltage Vin and the line side terminal voltage Vout obtained by applying the input signal,

To derive the impedance of the sample lightning arrester by

A step of deriving a phase difference between the ground side terminal voltage Vin and the line side terminal voltage Vout of the sample lightning arrester;

The step of deriving the series component resistance value of the sample lightning arrester by
Plotting the derived series component resistance values on a logarithmic axis from less than about 1 kHz to frequencies exceeding about 1 MHz to obtain a frequency characteristic curve specific to the sample arrester;
When the deviation of more than the set amount is recognized in the frequency characteristic curve specific to the sample lightning arrester and the frequency characteristic curve of the normal lightning arrester, and the deviation is confirmed at 1 kHz or less,
If the deviation is not confirmed at 1 kHz or less and is confirmed at 100 kHz or more, a step of determining a partially destroyed product is performed.

  An input signal that reaches a frequency that is less than about 1 kHz to more than about 1 MHz differs depending on the specifications of the lightning arrester, but is several Hz, several tens Hz, or several hundred Hz to several MHz, several tens MHz, or several hundred MHz. These can be changed as appropriate.

  As for the number of samplings and the number of plots obtained by quantifying the output signal in the frequency domain of the input signal, it is desirable to take a large number of samples as long as the capability of the calculation means allows to obtain a practical calculation speed. On the other hand, as long as practical judgment accuracy is obtained, it is not necessary to collect more samples than necessary. Therefore, it is desirable to secure at least the number of samplings when obtaining the frequency characteristic curve of a normal product and to collect samples over the entire range of frequencies at the time of sample acquisition when obtaining at least the frequency characteristic curve of a normal product.

  In the determination step, when the deviation is confirmed at 1 kHz or less, it may be confirmed at any point of 1 kHz or less, and when it is confirmed at 100 kHz or more, it may be confirmed at any point of 100 kHz or more. good.

As described above, according to the lightning arrester failure determination method according to the present invention, not only a simple numerical comparison but also a process of comparing resistance value disparities in specific frequency bands is adopted. Therefore, the technical improvement and efficiency improvement of the lightning arrester used for electric power equipment can be achieved.
Moreover, the reliability of electric power equipment can be maintained by finding a lightning arrester that has been partially destroyed.

It is an internal equivalent circuit of the lightning arrester in which the failure determination method of the lightning arrester by this invention is used. It is a graph which shows an example of the serial component resistance value (calculated value) with respect to the frequency of the lightning arrester in which the failure determination method of the lightning arrester by this invention is used. It is a graph which shows an example of the serial component resistance value (measured value) with respect to the frequency of the lightning arrester (what was applied to the actual power transmission line) in which the failure determination method of the lightning arrester by this invention is used. It is a block diagram which shows an example of the measuring device used for the failure determination method of the lightning arrester by this invention. It is an electric circuit diagram which shows an example of the measurement circuit used for the failure determination method of the lightning arrester by this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a failure determination method for a device (hereinafter referred to as a lightning arrester) in which devices having a continuity blocking function according to the present invention are connected in series will be described below with reference to the drawings.
The present invention makes it possible to determine the state of a lightning arrester that has been partially destroyed by measuring the electrical characteristics of the lightning arrester.

Usually, a lightning arrester has a plurality of zinc oxide elements (hereinafter referred to as elements) connected in series, and can be represented by an internal equivalent circuit shown in FIG.
This is a circuit in which a resistance component and a capacitance component are connected in parallel. An equivalent circuit of a lightning arrester in which a plurality of elements are connected in series is a series component resistance value and a series component. It can also be expressed in a form converted to a reactance value.

  At that time, the series component resistance value and the series component reactance value for one element are as shown in the following formula 1, and the series component resistance value and the series component reactance value when a plurality of elements are connected in series are shown in the following formula 2. It will be a thing.

（酸化亜鉛素子一個分）

(For one zinc oxide element)

FIG. 2 shows the results of calculation and estimation of normal products, completely destroyed products, and partially destroyed products using the series component resistance values of this equation.
This measurement result is
Normal product (resistance value 20 MΩ / element: capacitance value 120 pF),
Completely destroyed product (resistance value 160MΩ / element: capacitance value 120pF),
Partially destroyed product (resistance value 4 kΩ / element: capacitance value 120 pF)
Only one element is destroyed. Other elements are the same as normal products).

  Assuming that the resistance value of the destroyed element is reduced by a flashover, the normal product is a lightning arrester in which the resistance value of all elements is not reduced, and the complete destruction product is the resistance value of all elements. A lightning arrester that has been reduced, and a partially destroyed product is a lightning arrester in which a device whose resistance value has decreased and a device that has not decreased are mixed.

Then, in a normal product, the resistance value corresponding to the capacitance decreases as the frequency increases, so that the series resistance component decreases (see FIG. 2).
In a completely destroyed product, since all elements are destroyed and the resistance value is lowered, the resistance value does not change even if the frequency is increased and becomes constant.
In the partially destroyed product, the elements that are destroyed and the elements that are not destroyed are connected in series and mixed, and the transition point of the characteristics of each element is different. However, the high frequency shows the same tendency as the completely destroyed product, and the difference from the normal product becomes clear.
By using the difference in characteristics described above, it is possible to determine a lightning arrester that has been partially destroyed.

The flow of the lightning arrester failure determination method according to the present invention will be specifically described below.
The failure determination method according to the present embodiment collects a sample, prepares a measuring instrument (see FIG. 4), and measures the series component resistance value-frequency characteristics (hereinafter referred to as frequency characteristics) measured by the measurement circuit shown in FIG. Is something to get.

  The measuring instrument includes a generator 1 that can continuously generate an AC signal from about 1 Hz to about 1000 MHz, a probe 2 that detects an output signal corresponding to the input signal, an arithmetic means 3 that performs an operation on the output signal, The plotter 4 that realizes the frequency characteristic curve plotting the calculation result on the common logarithmic axis on the memory or on the screen, and the difference in DC component resistance between the normal product and the sample in the region below the set frequency and above the set frequency. The comparison unit 5 leads and a determination unit 6 that outputs a determination of a normal product, a partially destroyed product, or a completely destroyed product from the comparison result.

As for the frequency characteristics, measuring devices are connected to both ends of a lightning arrester separated from a power transmission line, and a signal is supplied by the generator 1 while changing the frequency from 100 Hz to 100 MHz.
The output signal is detected through the probe 2 and the resistance value is derived by the arithmetic means 3 by the above formulas (1) to (3).

  The plotter 4 plots the derived resistance value on a virtual logarithmic axis on the memory and on the display to obtain a frequency characteristic curve specific to the sample.

  The comparison unit 5 compares the measured frequency characteristic curve of the sample with the characteristic curve of a normal product that has been held in advance, and the determination unit 6 relatively detects a trend shift and a significant increase or decrease in the resistance value. The determination is made based on a predetermined criterion based on the difference in change. The characteristic curve of the normal product is obtained by plotting the frequency characteristics of the normal product obtained by the same procedure as the sample on the common logarithmic axis.

The criterion in the present embodiment is that when a deviation of a set amount or more is recognized in the characteristic curve of the sample and the normal product,
(1) When the deviation is confirmed at 1 kHz or less, it is determined that the product is completely destroyed.
(2) When the deviation is not confirmed at 1 kHz or less and is confirmed at 100 kHz or more, it is determined as a partially destroyed product.
That's it.

  Regarding the deviation of the frequency and the resistance value reflecting these determination criteria, the comparison unit 5 compares them with a predetermined set value or set amount as a reference. As an example of the reference, in the frequency band of 1 kHz or less in the determination of the completely destroyed product, the resistance value is about 100 times the measured value, and in the frequency band of 100 kHz or more in the determination of the partially destroyed product, the normal value of the resistance value. It is about five times the value (a value predetermined as a normal value at the actually measured frequency).

The determination unit 6 receives the comparison result, and performs a determination process of allocating to a normal product, a completely destroyed product, or a partially destroyed product based on the above determination criteria.
If the example of the above standard is used, if there is a deviation of about 100 times or more of the measured value between the measured value and the normal value of the resistance value intermittently or continuously in the frequency band of 1 kHz or less (the average of the frequency bands divided as appropriate) (It may be judged by the value) If it is judged as a completely destroyed product, and there is an intermittent or continuous deviation of about 5 times the normal value between the measured value and the normal value of the resistance value at 100 kHz or higher, it is a partially destroyed product. Is determined. As the determination result, various methods such as alarm or display can be adopted.

  It should be noted that these comparison processing and determination processing can be performed visually by the measurer. In the case of visual observation, it is not always necessary to determine the difference in resistance value with respect to the frequency, and it may be determined sensuously by the difference between the frequency characteristic curve of the normal product and the frequency characteristic curve of the sample.

FIG. 3 shows the result of a characteristic test of the lightning arrester attached to the actual power transmission line.
It has also been confirmed from actual measurements that a completely destroyed product is 1 kHz or less and a normal product is 2 MΩ or more, and an explosive product has been confirmed to be about 2 kΩ.
For a partially destroyed product, the theoretical formula (see Fig. 2) assumes a deviation of about 10 times at 100 kHz, assuming that the resistance value of the damaged element is 2 kΩ. It can be confirmed that the sample is a partially destructive product from the situation of a characteristic change in which the difference in resistance value increases with the increase of and the deviation of about 5 to 10 times can be confirmed at the same frequency.

1 generator, 2 probe, 3 calculation means, 4 plotter,
5 comparison part, 6 judgment part,

Claims (1)

Connect a signal source to the ground side terminal and line side terminal of the sample lightning arrester, apply an input signal that reaches a frequency of less than about 1 kHz to more than about 1 MHz, and obtain the ground side terminal voltage Vin obtained by applying the input signal and the line side From the output signal of terminal voltage Vout,

To derive the impedance of the sample lightning arrester by

A step of deriving a phase difference between the ground side terminal voltage Vin and the line side terminal voltage Vout of the sample lightning arrester;

The step of deriving the series component resistance value of the sample lightning arrester by
Plotting the derived series component resistance values on a logarithmic axis from less than about 1 kHz to frequencies exceeding about 1 MHz to obtain a frequency characteristic curve specific to the sample arrester;
If the difference between the frequency characteristic curve specific to the sample lightning arrester and the frequency characteristic curve of the normal lightning arrester is greater than the set amount, and the difference is confirmed at 1 kHz or less,
If the difference is not confirmed at 1 kHz or less and is confirmed at 100 kHz or more, a step of determining a partially destroyed product;
A method for determining a failure of a lightning arrester, characterized by undergoing

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