JPS6358115A - Detection and diagnosis for mechanical deterioration in insulator by acoustic emission - Google Patents

Abstract

PURPOSE:To enable proper judgement of the life of an insulator to be inspected due to mechanical deterioration, by a method wherein a tension load is applied to the insulator being inspected to detect acoustic emission (AE) generated, and reference is made to the relationship between a load and deterioration as obtained for a sound insulator. CONSTITUTION:Acousto-electric converters 4 are stuck, for example, on the surface of a ceramic part 2 near a support pin 1 fastened at the center of an insulator by a cement 3 to detect AE (for example, means of the results of four converters 4 is obtained). As for a sound insulator experiencing not load, a tension load led to cause a damage to the insulator and progress in the deterioration in the cement portion 3 are examined to determine the relationship of the activity of the AE to these factors with constant loading conditions such as tension speed. Then, the relationship thus obtained is compared to the relationship between total activity of AE and applied loads for a desired number of insulators removed from a power transmission system. This enables to inform the previous loads applied on the insulators in the service, thereby finding the degree of progress in mechanical deterioration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a method for detecting and diagnosing mechanical deterioration of an insulator due to acoustic emission.

(Technical Background of the Invention) Establishment of a diagnostic method for detecting electrical deterioration of insulators that support power transmission lines on steel towers and mechanical deterioration based on tensile loads caused by electric wires is an important way to maintain stable power transmission systems by always maintaining them in a healthy state. It is indispensable to enable electricity supply and demand.

By the way, since there are many opportunities for electrical deterioration, research has been conducted for a long time regarding the detection and diagnosis of electrical deterioration. Contributes to improved conversion. However, research into mechanical deterioration has lagged far behind, and there is currently no evidence of this.

Therefore, for example, the tensile load that an insulator should have is 2.2 times the maximum working load for hard copper wire, and 2.2 times the maximum working load for other wires.
．． In addition to providing a safety factor of 5 times, measures are taken to prevent accidents due to deterioration by replacing all insulators in the target power transmission system all at once after a period of use determined by experience. ing.

However, the tensile load applied to the insulator by the wire is not determined solely by the weight of the wire; it is also subject to uncertain factors such as the weight of ice and snow adhering to the wire, vibrations caused by the wind, and even the expansion and contraction of the wire due to temperature changes. It changes depending on various weather conditions. For this reason, it is difficult to specifically give a reliable maximum working load, and to date, there has been no actual measuring method or actual measuring data available for the maximum tensile load that an insulator has received in the past. Therefore, when setting the maximum working load, it is necessary to rely largely on experience. For example, an insulator with a tensile load higher than necessary may be used, which may impair economic rationality. Even if all insulators are replaced at once, there is a risk that insulators that have not deteriorated will be replaced, and this may also lack economic rationality.

Therefore, in recent years, attention has begun to be paid to rational countermeasures against mechanical deterioration caused by tensile loads on insulators, in order to further reduce power costs, further improve the reliability of power transmission equipment, and improve maintenance efficiency. Accordingly, there is a need for an effective method for detecting and diagnosing mechanical deterioration.

(Object of the invention) The present invention realizes a method for actually measuring the maximum tensile load that an insulator has received in the past, provides an actual measurement basis for the maximum working load at least for power transmission systems under the same conditions, and further develops this method. The present invention provides a deterioration detection and diagnosis method that can appropriately determine the lifespan due to deterioration of an insulator. Next, the details will be explained using the drawings.

(Principle of the Invention) It is known that when a load is applied to a solid material such as metal or rock, sound as shown in FIG. 1 (al) is emitted from the solid material (Acoustic Emission (abbreviated as AE)).

The present invention was made by utilizing this AB, and when this was investigated on the cristothumarite 2501 ball and socket type suspension insulator currently used in power transmission systems, the following results were found. It has become clear that a characteristic phenomenon is exhibited, and that this phenomenon can be similarly obtained with other suspension insulators such as clevis type or alumina insulators. In other words, the occurrence of AE is small up to a load of ■, but once this load is exceeded, it tends to increase rapidly. When examining the relationship with the sum of degrees (referred to as the sum of degrees), it becomes a broken line like the curve shown in Figure 2. Note that SI in the figure is its AE.
Indicates the conversion point for the number of occurrences. In addition, in the case of insulators with a history of AE, please refer to Tables 1 and 3.
As shown in the figure, the larger the load received in the past, the smaller the number of AE occurrences, and the sharp transition point of the number of AE occurrences moves toward the larger load. And B and C in Figure 2
It was revealed that the curved line was a broken line, and that the load at the conversion point S was approximately the maximum load that had been applied in the past, as shown in Table 1.

The decrease in AE activity in this experimental fact is thought to be due to the release of AE due to the load applied to the insulator in the past, and the fact that the load at the conversion point indicates the load applied in the past. This is thought to be due to the Keiser effect, but in any case, this fact allows us to know the history of loads (stress) that the insulator has received in the past.

Table 1 On the other hand, in suspension insulators, the porcelain part generally does not break due to tensile loads, and as the applied load increases, the support bottle (1) shown in Figure 4 is finally fixed at the center of the porcelain part (2). This would cause damage to the cement part (3). Therefore, it is possible to know the relationship between the load applied to the insulator and the state of deterioration of the cement part, which is a sign of pin damage.

Therefore, for example, as shown in Figure 5, cement (3) is placed in the center of the insulator.
For example, a method is used to detect AE by attaching an acoustic-electrical transducer (4) to the surface of the porcelain part (2) near the support pin (11) fixed by the support pin (11) (in the figure, four transducers (4)
), the progress of the tensile load and deterioration of the cement part until the bottle is damaged under the same loading conditions such as the tensile speed for a sound insulator that has not been subjected to any load beforehand. We will investigate the relationship between this and the activity level of AE related to this. Then, by comparing this with the relationship between the load applied to an arbitrary number of insulators removed from the power transmission system and the sum of the AE activities, we can find out the past load applied to the insulators during use. From this, the degree of progress of mechanical deterioration can be determined. That is, ■ When comparing the relationship between the load and the sum of the AE activities shown in curves A and 3 in Figure 2 above for a sound insulator and a deteriorated test insulator used in the power transmission system, it is found that the past load Since the AE activity level of the insulator subjected to the test is lower than that of the insulator that is not subjected to the load, it can be confirmed whether or not the deteriorated test insulator has been subjected to the load in the past.

■ From the relationship diagram between the load applied to the deteriorated test insulator and the total AE activity (see curve B in Figure 2), find the load S at the point of change in slope and find out the magnitude of the load it has received in the past. By applying this to the relationship between the tensile load up to bottle damage and the progress of deterioration of the cement part, which was determined in advance for a sound insulator, it is possible to know specifically how much deterioration has progressed.

(Effect of the invention) Therefore, for example, by removing an arbitrary number of insulators as samples from sections of a power transmission system that are subjected to the same weather conditions (using the same electric wires), and diagnosing the degree of deterioration using the present invention,
If the group of insulators in the target section are replaced depending on the results, it is possible to replace insulators that have not deteriorated as much as in the conventional case where all the insulators are replaced at once after a certain period of use based on experience. Since there is no risk of damage, maintenance can be performed rationally and efficiently without the risk of economic loss.

Furthermore, according to the present invention, it is possible to know the maximum working load of the insulator in the target section of the power transmission system, so it is possible to appropriately select the tensile strength that the insulator should have.

Furthermore, if an appropriate method of applying load to the insulators under the conditions in which they are actually used in the power transmission system can be devised, it would be possible to prevent deterioration from time to time by attaching acoustic-electric converters to an appropriate number of insulators in advance. The condition can be diagnosed.

(Others) Although the Itogi invention has been described with reference to an embodiment, measurement errors may occur due to external noise when measuring AE using an acoustic-electrical converter.
:do. For example, as shown in Fig. 1, the detected A
It is better to remove the noise N by detecting the IE waveform (Figure (a)) (Figure (BL)) and cutting the darkness value below 17. Also, in determining the slope conversion point S, As shown in Fig. 5, a preamplifier (
5) and signal conditioner (6) and analog
A digital converter (7) may be provided, and the AE waves detected thereby may be added to the electronic computer (8) to be determined. In the present invention, the AE254S model manufactured by Fuji Ceramic Co., Ltd. is used as the sound M-electrical converter, and its output is amplified by 1odn with a preamplifier (5), then amplified by 20dll with a signal conditioner (6), and then A/D converted. The results were recorded on a porcelain disk and processed using an electronic computer to achieve the purpose.

Furthermore, in the above, deterioration is determined based on the relationship between the static load and the sum of the AE activities. However, instead of the static 11: i weight, we apply a dynamic load that increases stepwise as shown in Figure 6 to find the average load, and at the same time calculate the number of AE events at each stage and the average energy of the An. The correlation between is calculated using the following formula.

Y-b
As shown in Fig. 7, it is also possible to know the load received in the past from the change point S.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of acoustic emission (AE), Figure 2 is 4;fl
A diagram of the relationship between lj and the number of AE events. Figure 3 is an explanatory diagram of how the number of AE events changes depending on the magnitude of the load received in the past.
Figure 4 is an explanatory diagram of a ball-and-socket type suspension insulator, Figure 5 is a layout diagram and measurement circuit diagram of an acoustic-electrical converter, and Figures 6 and 7 are other explanatory diagrams for determining loads received in the past. It is. (1)...Support bottle, (2)...Porcelain part of the insulator,
(3)...Cement 1 part, (4)...Acoustic-electrical converter, (5)...Preamplifier, (6)...Signal conditioner, (7)...Al1) converter , (8
)···Electronic computer. ku light〉―〜Sugaj''工;'f＜ -WgiC?-1
-- Voice 5, 6, 6 or 7 Proceeding Authorization (self-motivated) December 3, 1985 Director-General of the Patent Office Kuro 1) Akio Tono 1, Indication of Case Patent Application No. 1981-201375 2, Invention Diagnosis method for detecting mechanical deterioration of insulators due to acoustic emission (AE) 3, relationship with the case of the person making the amendment Applicant: Central Research Institute of Electric Power Industry 407.1ka and 1 other person: 1- Nishi-Shinjuku, Shinjuku-ku, Tokyo 23-1 5, "Detailed Description of the Invention" column of the specification subject to amendment and drawing 6, Contents of amendment 1 Correction of the specification (1) Page 4, line 13 (Emission)
sion). (2) On page 7, lines 3 and 11, [bin] is corrected to [insulator]. (3) On page 8, line 11, [pin] is corrected to [insulator]. (4) On page 10, line 10, [porcelain] is corrected to [magnetic]. ■1 Correction of drawings Figures 3 and 7 should be corrected as shown in the attached sheet. (Figure 3 [incidence] has been corrected to [number of occurrences], Figure 7 [correlation] has been corrected to [correlation]) 1,000 yen (direct

Claims (1)

[Claims] Acoustic emission (AE) that occurs within an insulator when a tensile load is applied
), and by using the fact that the relationship between the emitted acoustic waves and the load changes depending on the load applied in the past, the historical load is determined, and this is compared with the relationship between the load and deterioration obtained for a sound insulator. 1. A method for detecting and diagnosing mechanical deterioration of an insulator using acoustic emission (AE), the method comprising diagnosing the degree of deterioration using acoustic emission (AE).