Transformer bushing lower porcelain structure and its leakage detection method

Abstract

The present invention is a transformer bushing lower porcelain structure and a leakage detection method thereof, the structure comprises an integrally connected hollow first equal-diameter body, a frustum part and a second equal-diameter body, the side wall of the first equal-diameter body is provided with a plurality of first through holes that can be closed at both ends; the side wall of the frustum part is provided with a plurality of second through holes that can be closed at both ends, the central axis of each second through hole is arranged along the busbar of the frustum part; the side wall of the second equal-diameter body is provided with a plurality of third through holes that can be closed at both ends; each first through hole, each second through hole and each third through hole is filled with insulating oil. On the basis of meeting the strength and insulation performance requirements, the present invention prolongs the time from the leakage of the internal medium of the transformer bushing lower porcelain structure to the occurrence of an accident, and provides a detection method for checking whether the transformer bushing lower porcelain structure has leakage during maintenance, and a corresponding maintenance or replacement plan can be formulated according to the leakage situation.

Description

Technical Field

[0001] The invention relates to the technical field of high-voltage electric power equipment, and in particular to a transformer bushing lower porcelain component structure and a leakage detection method thereof. Background Art

[0002] The transformer (high-voltage) bushing is the main insulation device outside the transformer (high-voltage) box. The oil-immersed transformer (high-voltage) bushings of 72.5kV and above voltage levels all have a lower porcelain sleeve 8. The lower porcelain sleeve is mainly used for insulation support of the lead wire of the power transmission and transformation equipment or as an insulating container. Its structure diagram is as follows Fig.14 As shown. As an important insulating device in high-voltage power equipment, porcelain bushings need to ensure the stability and safety of their operation as the power grid is laid at a large scale and high density. Due to the long-term test of harsh working environment, porcelain bushings are prone to internal insulating oil leakage, resulting in the decline of its heat dissipation and insulation performance. The Joule heat of electrical equipment accumulates inside the porcelain bushing, eventually causing the porcelain bushing to explode, endangering people's lives and property and the safety of the power grid.

[0003] The existing solution is a single-layer porcelain sleeve, and the leakage detection method is a gas detector. Once a single-layer porcelain sleeve leaks, the internal medium will directly contact the external air. The internal insulating oil will produce acetylene under the discharge of the conductive metal guide rod. After contacting the air, it is easy to cause the porcelain sleeve to explode under the action of the arc. The single-layer porcelain sleeve can only perform online leakage monitoring, and cannot perform corresponding leakage status assessment during maintenance. Often, internal medium leakage and accidents occur almost at the same time, and there is a lack of prevention mechanism.

[0004] Therefore, the inventor, relying on his many years of experience and practice in related industries, proposes a transformer bushing lower porcelain structure and a leakage detection method thereof to overcome the defects of the prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a transformer bushing lower porcelain structure and a leakage detection method thereof, so as to overcome the problems existing in the prior art. The present invention prolongs the time from the leakage of the internal medium of the transformer bushing lower porcelain structure to the occurrence of an accident on the basis of meeting the strength and insulation performance requirements, and provides a detection method for checking whether the transformer bushing lower porcelain structure has leakage during maintenance, and a corresponding maintenance or replacement plan can be formulated according to the leakage situation.

[0006] The objective of the present invention is achieved in this way. A transformer bushing lower porcelain structure comprises a hollow first equal-diameter body, a frustum part and a second equal-diameter body connected in an integral manner. A plurality of first through holes that can be closed at both ends are arranged in the side wall of the first equal-diameter body, and the central axis of each of the first through holes is arranged parallel to the central axis of the first equal-diameter body; a plurality of second through holes that can be closed at both ends are arranged in the side wall of the frustum part, and the central axis of each of the second through holes is arranged along the busbar of the frustum part; a plurality of third through holes that can be closed at both ends are arranged in the side wall of the second equal-diameter body, and the central axis of each of the third through holes is arranged parallel to the central axis of the second equal-diameter body; each of the first through holes, each of the second through holes and each of the third through holes is filled with insulating oil.

[0007] In a preferred embodiment of the present invention, one end of each of the first through holes away from the frustum portion is sealed and connected to the first end cover; one end of each of the third through holes away from the frustum portion is sealed and connected to the second end cover.

[0008] In a preferred embodiment of the present invention, the insulating oil filled in each of the first through holes, each of the second through holes and each of the third through holes is arranged in a bubble-free state.

[0009] In a preferred embodiment of the present invention, each of the first through holes, each of the second through holes and each of the third through holes are correspondingly connected.

[0010] In a preferred embodiment of the present invention, each of the first through holes, each of the second through holes and each of the third through holes are staggered in the circumferential direction.

[0011] In a preferred embodiment of the present invention, the wall thickness of the first equal-diameter body, the wall thickness of the frustum portion and the wall thickness of the second equal-diameter body are set equally; each of the first through holes is set at half the wall thickness of the first equal-diameter body, and each of the second through holes is set at half the wall thickness of the frustum portion; and each of the third through holes is set at half the wall thickness of the second equal-diameter body.

[0012] The purpose of the present invention can also be achieved in this way. A leakage detection method for a porcelain structure under a transformer bushing includes visually detecting leakage of an outer wall of the porcelain structure under the transformer bushing; and detecting leakage of the inside of a side wall and an inner wall of the porcelain structure under the transformer bushing by ultrasonic longitudinal waves.

[0013] In a preferred embodiment of the present invention, when the porcelain structure under the transformer bushing is intact and leak-free, a portion of the ultrasonic longitudinal waves generates a first interface reflection wave at the interface between the first through hole, the second through hole and the third through hole near the outside, a portion of the ultrasonic longitudinal waves generates a second interface reflection wave at the interface between the first through hole, the second through hole and the third through hole near the inside, and a portion of the ultrasonic longitudinal waves propagates through the insulating oil and generates a third interface reflection wave at the inner wall of the porcelain structure under the transformer bushing, and the amplitudes of the three interface reflection waves decrease successively.

[0014] In a preferred embodiment of the present invention, when there is no leakage point on the outer wall and a small defect occurs on the outside of the first through hole, the second through hole and / or the third through hole, a defect signal will be generated in front of the first interface reflection wave, and the amplitudes of the second interface reflection wave and the third interface reflection wave will be reduced.

[0015] In a preferred embodiment of the present invention, when there is no leakage point on the outer wall and a large defect occurs on the outside of the first through hole, the second through hole or / and the third through hole, a defect signal will be generated in front of the first interface reflection wave. The defect signal has a high amplitude, and the first interface reflection wave, the second interface reflection wave and the third interface reflection wave are blocked by the defect signal and are not visible.

[0016] In a preferred embodiment of the present invention, when there is no leakage point on the outer wall and a small defect is generated on the inner side of the first through hole, the second through hole and / or the third through hole, the first interface reflection wave remains unchanged, a defect signal is generated behind the second interface reflection wave, and the amplitude of the third interface reflection wave is reduced.

[0017] In a preferred embodiment of the present invention, when there is no leakage point on the outer wall and a large defect occurs on the inner side of the first through hole, the second through hole or / and the third through hole, the first interface reflection wave remains unchanged, a defect signal is generated behind the second interface reflection wave, and the third interface reflection wave is blocked by the defect signal and is invisible.

[0018] In a preferred embodiment of the present invention, when there is no leakage point on the outer wall and a small defect occurs on the inner wall of the porcelain structure under the transformer bushing, a bubble signal is generated between the inner wall and the outer wall of the first through hole, the second through hole or / and the third through hole, a defect signal is generated after the second interface reflection wave, and a defect signal is generated before the third interface reflection wave, and the amplitudes of the second interface reflection wave and the third interface reflection wave are reduced.

[0019] In a preferred embodiment of the present invention, when there is no leakage point on the outer wall and a large defect occurs on the inner wall of the porcelain structure under the transformer bushing, the ultrasonic longitudinal wave is reflected at the interface close to the outside of the first through hole, the second through hole and the third through hole to form a first interface reflection wave, and the amplitude of the first interface reflection wave increases, and there is no second interface reflection wave and third interface reflection wave.

[0020] As described above, the transformer bushing lower porcelain component structure and leakage detection method thereof provided by the present invention have the following beneficial effects:

[0021] In the transformer bushing lower porcelain structure provided by the present invention, a first through hole, a second through hole and a third through hole are arranged in the side wall, and insulating oil is filled in the through holes to meet the strength requirements when under pressure, and the insulating oil supplements the insulation performance loss caused by digging holes; the first through hole, the second through hole and the third through hole constitute a priority damage structure, and the first through hole, the second through hole and the third through hole are closed structures, and the damage usually stops at the first through hole, the second through hole and the third through hole, and will not penetrate the entire transformer bushing lower porcelain structure, thereby preventing the medium inside the transformer bushing lower porcelain structure from contacting with the outside air; after the transformer bushing lower porcelain structure is damaged on one side, the remaining structure can still meet the insulation performance, thereby extending the time when the accident occurs, and the leakage position can be found during shutdown and maintenance, and the damaged transformer bushing lower porcelain structure can be repaired or replaced;

[0022] The leakage detection method of the porcelain structure under the transformer bushing of the present invention is simple to operate and has intuitive detection results, which is conducive to timely discovering leakage and avoiding faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0024] in:

[0025] Figure 1 : It is a cross-sectional view of the porcelain structure under the transformer bushing of the present invention.

[0026] Figure 2 :for Figure 1 Middle AA section view.

[0027] Figure 3 : It is a schematic diagram of using an ultrasonic detector to perform leakage detection on the porcelain structure under the transformer bushing of the present invention.

[0028] Figure 4 :for Figure 3 Middle BB section view.

[0029] Figure 5 : is a schematic diagram of the detection process of leakage of the inner wall of the lower porcelain structure of the transformer bushing of the present invention.

[0030] Figure 6 :for Figure 5 Middle CC section view.

[0031] Figure 7 : Schematic diagram of reflected echo when the porcelain structure under the transformer bushing is intact and has no leakage.

[0032] Figure 8: Schematic diagram of reflected echo when there is no leakage point on the outer wall and a small defect occurs on the outside of the through hole.

[0033] Fig. 9 : Schematic diagram of reflected echo when there is no leakage point on the outer wall and a large defect occurs on the outside of the through hole.

[0034] Fig.10 : Schematic diagram of reflected echo when there is no leakage point on the outer wall and a small defect occurs on the inner side of the through hole.

[0035] Fig.11 : Schematic diagram of reflected echo when there is no leakage point on the outer wall and a large defect occurs on the inner side of the through hole.

[0036] Fig.12 : Schematic diagram of reflected echo when there is no leakage point on the outer wall and a small defect occurs on the inner wall of the porcelain structure under the transformer bushing.

[0037] Fig.13 : Schematic diagram of reflected echo when there is no leakage point on the outer wall and a large defect occurs on the inner wall of the porcelain structure under the transformer bushing.

[0038] Fig.14 : It is a structural schematic diagram of the lower porcelain sleeve in the prior art.

[0039] In the figure:

[0040] 100. The porcelain structure under the transformer bushing;

[0041] 1. The first equal diameter body;

[0042] 2. Cone part;

[0043] 3. a first through hole;

[0044] 4. a second through hole;

[0045] 5. Insulating oil;

[0046] 6. Ultrasonic detector;

[0047] 7. Cracks;

[0048] 8. Lower porcelain sleeve;

[0049] 9. Second equal diameter body;

[0050] 10. The third through hole. DETAILED DESCRIPTION

[0051] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0052] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0054] like Figure 1 , Figure 2 As shown, the present invention provides a transformer bushing lower porcelain structure 100, comprising a hollow first equal diameter body 1, a frustum 2 and a second equal diameter body 9 (such as Figure 1 As shown, the diameter of the second equal-diameter body 9 is smaller than that of the first equal-diameter body 1, which can be called a small platform), and the transformer bushing lower porcelain structure 100 still adopts a single-layer structure; a plurality of first through holes 3 that can be closed at both ends are provided in the side wall of the first equal-diameter body 1, and the central axis of each first through hole 3 is arranged parallel to the central axis of the first equal-diameter body 1; a plurality of second through holes 4 that can be closed at both ends are provided in the side wall of the frustum 2, and the central axis of each second through hole 4 is arranged along the busbar of the frustum 2; a plurality of third through holes 10 that can be closed at both ends are provided in the side wall of the second equal-diameter body 9, and the central axis of each third through hole 10 is arranged parallel to the central axis of the second equal-diameter body 9; each first through hole 3, each second through hole 4 and each third through hole 10 is filled with insulating oil 5.

[0055] Since the main force borne by the transformer bushing lower porcelain structure 100 is pressure, processing through holes (first through hole 3, second through hole 4 and third through hole 10) in the transformer bushing lower porcelain structure 100 will reduce its strength less and meet its strength requirements. The first through hole 3, the second through hole 4 and the third through hole 10 are filled with insulating oil, which can make up for the loss of insulation performance caused by digging holes. The first through hole 3, the second through hole 4 and the third through hole 10 are discontinuous parts in the structure. The damage to the transformer bushing lower porcelain structure 100 caused by operation or abnormal conditions will first occur at the first through hole 3, the second through hole 4 and the third through hole 10, and because the first through hole 3, the second through hole 4 and the third through hole 10 are closed structures, the damage usually stops at the first through hole 3, the second through hole 4 and the third through hole 10, and will not penetrate the entire transformer bushing lower porcelain structure 100, avoiding the medium inside the transformer bushing lower porcelain structure 100 from contacting the outside air.

[0056] After the transformer bushing lower porcelain structure 100 is damaged on one side, the remaining structure can still meet the insulation performance requirements, thus extending the time before an accident occurs. During shutdown and overhaul, the leakage location can be found, and the damaged transformer bushing lower porcelain structure 100 can be repaired or replaced.

[0057] In the transformer bushing lower porcelain structure provided by the present invention, a first through hole, a second through hole and a third through hole are arranged in the side wall, and insulating oil is filled in the through holes to meet the strength requirements when under pressure, and the insulating oil supplements the insulation performance loss caused by digging holes; the first through hole, the second through hole and the third through hole constitute a priority damage structure, and the first through hole, the second through hole and the third through hole are closed structures. The damage usually stops at the first through hole, the second through hole and the third through hole, and will not penetrate the entire transformer bushing lower porcelain structure, thereby avoiding the medium inside the transformer bushing lower porcelain structure from contacting with the outside air; after the transformer bushing lower porcelain structure is damaged on one side, the remaining structure can still meet the insulation performance, thereby extending the time when the accident occurs, and the leakage position can be found during the shutdown and maintenance period, and the damaged transformer bushing lower porcelain structure can be repaired or replaced.

[0058] Furthermore, one end of each first through hole 3 away from the frustum portion is sealed and connected to the first end cover; one end of each third through hole 10 away from the frustum portion is sealed and connected to the second end cover.

[0059] Furthermore, the insulating oil filled in each of the first through holes 3 , each of the second through holes 4 and the third through holes 10 is arranged in a bubble-free state.

[0060] The first through holes 3, the second through holes 4 and the third through holes 10 are filled with insulating oil, and bubbles inside the insulating oil are eliminated by vibration or heating, and then the first end cover and the second end cover are installed to ensure the sealing of the porcelain structure 100 under the transformer bushing.

[0061] Furthermore, each first through hole 3, each second through hole 4 and the third through hole 10 can be connected to each other correspondingly, and each first through hole 3, each second through hole 4 and the third through hole 10 can also be staggered in the circumferential direction. At this time, the connecting end surface of the first equal-diameter body 1 and the frustum portion 2, and the connecting end surface of the second equal-diameter body 9 and the frustum portion 2 constitute the end sealing surface of each second through hole 4, the first end cover and the connecting end surface of the first equal-diameter body 1 and the frustum portion 2 constitute the end sealing surface of each first through hole 3, and the second end cover and the connecting end surface of the second equal-diameter body 9 and the frustum portion 2 constitute the end sealing surface of each third through hole 10.

[0062] In this embodiment, the wall thickness of the first equal-diameter body 1, the wall thickness of the frustum portion 2 and the wall thickness of the second equal-diameter body 9 are set equally; each first through hole 3 is set at half the wall thickness of the first equal-diameter body 1, each second through hole 4 is set at half the wall thickness of the frustum portion 2, and each third through hole 10 is set at half the wall thickness of the second equal-diameter body 9.

[0063] The present invention also provides a leakage detection method for a transformer bushing lower porcelain structure, comprising: visually detecting leakage of the outer wall of the transformer bushing lower porcelain structure 100; and detecting leakage of the inner wall and side wall of the transformer bushing lower porcelain structure 100 by ultrasonic longitudinal wave. Ultrasonic longitudinal wave detection is used, and ultrasonic longitudinal wave can propagate in liquid.

[0064] When the outer wall of the porcelain structure under the transformer bushing leaks, the leakage point on the outer wall is detected by visual inspection. When the outer wall leaks, there will be obvious leakage points, which can be judged by naked eyes.

[0065] like Figure 3 , Figure 4 As shown, the ultrasonic detector 6 is moved along the outer wall of the porcelain structure 100 under the transformer bushing, and the ultrasonic detector 6 emits ultrasonic longitudinal waves. When the porcelain structure under the transformer bushing is intact and leak-free, a part of the ultrasonic longitudinal waves generates a first interface reflection wave at the interface of the first through hole 3, the second through hole 4 and the third through hole 10 close to the outside (radially outside), a part of the ultrasonic longitudinal waves generates a second interface reflection wave at the interface of the first through hole 3, the second through hole 4 and the third through hole 10 close to the inside (radially inside), a part of the ultrasonic longitudinal waves propagates through the insulating oil and generates a third interface reflection wave at the inner wall of the porcelain structure under the transformer bushing, and the amplitudes of the three interface reflection waves decrease in sequence (the amplitude of the second interface reflection wave will vary according to the different probe parameters selected, and its amplitude may be higher than the amplitudes of the first interface reflection wave and the third interface reflection wave, because the reflection area of ​​the inner wall of the porcelain structure under the transformer bushing is larger than the reflection area of ​​the through hole, and the width of the third interface reflection wave will be wider than the widths of the first interface reflection wave and the second interface reflection wave). The reflected echo of the complete structure is shown in FIG. Figure 7As shown, 16 is the ultrasonic detector transmitting wave. When leakage occurs inside the side wall and the inner wall of the transformer bushing lower porcelain structure 100, abnormal reflection will occur, and the leakage of the transformer bushing lower porcelain structure can be judged according to the reflected wave.

[0066] The first through hole 3, the second through hole 4 and the third through hole 10 are discontinuous parts in the structure. The wall thickness at the first through hole 3, the second through hole 4 and the third through hole 10 is thinner than that at other positions. Leakage will preferentially occur at the first through hole 3, the second through hole 4 and the third through hole 10. And because the first through hole 3, the second through hole 4 and the third through hole 10 constitute a closed structure, the damage usually stops at the first through hole 3, the second through hole 4 and the third through hole 10 and will not penetrate the entire porcelain sleeve.

[0067] like Figure 8 As shown, when there is no leakage point on the outer wall and a small defect (crack depth is less than or equal to 2 mm) occurs on the outside (radial outside) of the through hole (the first through hole 3, the second through hole 4 or / and the third through hole 10), a defect signal will be generated in front of the first interface reflection wave (through hole outer wall reflection wave), and the amplitudes of the second interface reflection wave (the first through hole 3, the second through hole 4 or / and the third through hole 10 inner wall reflection echo) and the third interface reflection wave (the inner wall reflection echo of the porcelain structure under the transformer bushing) will be reduced.

[0068] like Fig. 9 As shown, when there is no leakage point on the outer wall and a large defect (crack depth is greater than 2 mm) occurs on the outside (radial outside) of the through hole (the first through hole 3, the second through hole 4 or / and the third through hole 10), a defect signal will be generated in front of the first interface reflection wave. The defect signal has a high amplitude, and the first interface reflection wave, the second interface reflection wave and the third interface reflection wave are blocked by the defect signal and are not visible.

[0069] like Fig.10 As shown, when there is no leakage point on the outer wall and a small defect (crack depth is less than or equal to 2 mm) is generated on the inner side (radial inner side) of the through hole (first through hole 3, second through hole 4 or / and third through hole 10), the first interface reflection wave remains unchanged (same as the first interface reflection wave of the complete structure), a defect signal is generated behind the second interface reflection wave, and the amplitude of the third interface reflection wave is reduced.

[0070] like Fig.11 As shown, when there is no leakage point on the outer wall and a large defect (crack depth is greater than 2 mm) occurs on the inner side (radial inner side) of the through hole (first through hole 3, second through hole 4 or / and third through hole 10), the first interface reflection wave remains unchanged (same as the first interface reflection wave of the complete structure), a defect signal is generated behind the second interface reflection wave, and the third interface reflection wave is blocked by the defect signal and is invisible.

[0071] When there is no leakage point on the outer wall and the inner wall of the porcelain structure under the transformer bushing is defective, the ultrasonic longitudinal wave detection process is as follows: Figure 5 , Figure 6 shown.

[0072] like Fig.12 As shown, when there is no leakage point on the outer wall and a small defect occurs on the inner wall of the porcelain structure under the transformer bushing (the wall thickness reduction ratio is less than 5% or the crack depth is less than or equal to 2 mm), since the through holes (the first through hole 3, the second through hole 4 or / and the third through hole 10) weaken the overall structure, the defect on the inner wall of the porcelain structure under the transformer bushing will extend to the through holes (the first through hole 3, the second through hole 4 or / and the third through hole 10) and stop at the through holes. After the through hole structure is damaged, the internal liquid flows out, and a bubble signal is generated between the inner and outer walls of the through hole when a small amount flows out. A defect signal is generated after the second interface reflection wave, and a defect signal is generated before the third interface reflection wave. The amplitudes of the second interface reflection wave and the third interface reflection wave are lower than those of the complete structure.

[0073] like Fig.13 As shown, when there is no leakage point on the outer wall and a large defect occurs on the inner wall of the porcelain structure under the transformer bushing (falling off from the through hole to the inner wall or cracks extending from the through hole to the inner wall), since the through hole weakens the overall structure, the defect on the inner wall will extend to the through hole and stop at the through hole. After the through hole structure is damaged, the internal liquid flows out, causing all the insulating oil inside the through hole to flow out. The ultrasonic longitudinal wave is reflected at the interface of the first through hole 3, the second through hole 4 and the third through hole 10 close to the outside (radially outside) to form a first interface reflection wave, and its reflection amplitude is higher than when the structure is intact, and there is no second interface reflection wave and third interface reflection wave.

[0074] During the use of the porcelain structure under the transformer bushing, a gas alarm is used for real-time alarm, and ultrasonic testing is performed regularly to check whether there are cracks on the inner wall.

[0075] As described above, the transformer bushing lower porcelain component structure and leakage detection method thereof provided by the present invention have the following beneficial effects:

[0076] In the transformer bushing lower porcelain structure provided by the present invention, a first through hole, a second through hole and a third through hole are arranged in the side wall, and insulating oil is filled in the through holes to meet the strength requirements when under pressure, and the insulating oil supplements the insulation performance loss caused by digging holes; the first through hole, the second through hole and the third through hole constitute a priority damage structure, and the first through hole, the second through hole and the third through hole are closed structures, and the damage usually stops at the first through hole, the second through hole and the third through hole, and will not penetrate the entire transformer bushing lower porcelain structure, thereby preventing the medium inside the transformer bushing lower porcelain structure from contacting with the outside air; after the transformer bushing lower porcelain structure is damaged on one side, the remaining structure can still meet the insulation performance, thereby extending the time when the accident occurs, and the leakage position can be found during shutdown and maintenance, and the damaged transformer bushing lower porcelain structure can be repaired or replaced;

[0077] The leakage detection method of the porcelain structure under the transformer bushing of the present invention is simple to operate and has intuitive detection results, which is conducive to timely discovering leakage and avoiding faults.

[0078] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A leakage detection method for a porcelain structure under a transformer bushing, characterized in that: The transformer bushing lower porcelain structure comprises an integrally connected hollow first equal-diameter body, a frustum part and a second equal-diameter body, a side wall of the first equal-diameter body is provided with a plurality of first through holes that can be closed at both ends, and the central axis of each of the first through holes is arranged parallel to the central axis of the first equal-diameter body; a side wall of the frustum part is provided with a plurality of second through holes that can be closed at both ends, and the central axis of each of the second through holes is arranged along the busbar of the frustum part; a side wall of the second equal-diameter body is provided with a plurality of third through holes that can be closed at both ends, and the central axis of each of the third through holes is arranged parallel to the central axis of the second equal-diameter body; each of the first through holes, each of the second through holes and each of the third through holes is filled with insulating oil; The leakage detection method of the porcelain structure under the transformer bushing includes visually detecting the leakage of the outer wall of the porcelain structure under the transformer bushing; detecting the leakage of the inner wall and the inner wall of the porcelain structure under the transformer bushing by ultrasonic longitudinal waves; When the porcelain structure under the transformer bushing is intact and leak-free, a portion of the ultrasonic longitudinal waves generates a first interface reflection wave at the interface between the first through hole, the second through hole and the third through hole near the outside, a portion of the ultrasonic longitudinal waves generates a second interface reflection wave at the interface between the first through hole, the second through hole and the third through hole near the inside, and a portion of the ultrasonic longitudinal waves propagates through the insulating oil and generates a third interface reflection wave at the inner wall of the porcelain structure under the transformer bushing, and the amplitudes of the three interface reflection waves decrease successively.

2. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: One end of each of the first through holes away from the frustum portion is sealed and connected to the first end cover; one end of each of the third through holes away from the frustum portion is sealed and connected to the second end cover.

3. The leakage detection method for the porcelain structure under the transformer bushing according to claim 2, characterized in that: The insulating oil filled in each of the first through holes, each of the second through holes and each of the third through holes is arranged in a bubble-free state.

4. The leakage detection method for the porcelain structure under the transformer bushing according to claim 2, characterized in that: Each of the first through holes, each of the second through holes and each of the third through holes are correspondingly connected.

5. The leakage detection method for the porcelain structure under the transformer bushing according to claim 2, characterized in that: The first through holes, the second through holes and the third through holes are staggered in the circumferential direction.

6. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: The wall thickness of the first equal-diameter body, the wall thickness of the frustum portion and the wall thickness of the second equal-diameter body are set equally; each of the first through holes is set at half the wall thickness of the first equal-diameter body, and each of the second through holes is set at half the wall thickness of the frustum portion; each of the third through holes is set at half the wall thickness of the second equal-diameter body.

7. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: When there is no leakage point on the outer wall and a small defect occurs on the outside of the first through hole, the second through hole or / and the third through hole, a defect signal will be generated in front of the first interface reflection wave, and the amplitudes of the second interface reflection wave and the third interface reflection wave will decrease.

8. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: When there is no leakage point on the outer wall and a large defect occurs on the outside of the first through hole, the second through hole or / and the third through hole, a defect signal will be generated in front of the first interface reflection wave. The defect signal has a high amplitude, and the first interface reflection wave, the second interface reflection wave and the third interface reflection wave are blocked by the defect signal and are not visible.

9. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: When there is no leakage point on the outer wall and a small defect occurs inside the first through hole, the second through hole or / and the third through hole, the first interface reflection wave remains unchanged, a defect signal is generated behind the second interface reflection wave, and the amplitude of the third interface reflection wave is reduced.

10. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: When there is no leakage point on the outer wall and a large defect occurs inside the first through hole, the second through hole or / and the third through hole, the first interface reflection wave remains unchanged, a defect signal is generated behind the second interface reflection wave, and the third interface reflection wave is blocked by the defect signal and is invisible.

11. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: When there is no leakage point on the outer wall and a small defect occurs on the inner wall of the porcelain structure under the transformer bushing, a bubble signal is generated between the inner wall and the outer wall of the first through hole, the second through hole or / and the third through hole, a defect signal is generated after the second interface reflection wave, and a defect signal is generated before the third interface reflection wave, and the amplitudes of the second interface reflection wave and the third interface reflection wave are reduced.

12. The leakage detection method for the porcelain structure under the transformer bushing according to claim 1, characterized in that: When there is no leakage point on the outer wall and a large defect occurs on the inner wall of the porcelain structure under the transformer bushing, the ultrasonic longitudinal wave is reflected at the interface close to the outside of the first through hole, the second through hole and the third through hole to form a first interface reflection wave, the amplitude of the first interface reflection wave increases, and there is no second interface reflection wave and third interface reflection wave.

Images