A portable partial discharge tester

Abstract

The invention relates to the technical field of discharge testers, and discloses a portable partial discharge tester, comprising a tester body, wherein a geoelectric wave sensor and an ultrasonic detection head are arranged at the front end of the tester body. During partial discharge detection, the geoelectric wave sensor contacts a metal cabinet surface, the ultrasonic detection head is aligned with a gap at a cabinet door, the geoelectric wave sensor and an ultrasonic sensor in the ultrasonic detection head work simultaneously, the ultrasonic detection head has a grid hole array on its surface, a timing control component is arranged inside, a through hole is arranged on the timing control component, so that sound waves can only enter the ultrasonic detection head from the grid hole coincident with the through hole on the timing control component, the timing control component is driven by a driving component, so that the through hole on the timing control component changes position, the sound wave can enter the ultrasonic detection head from different grid holes at different timings, and is received by the ultrasonic sensor, and offset and focusing are generated through wave interference, so that the ultrasonic sensor can concentrate on sampling ultrasonic information.

Description

Technical Field

[0001] The invention relates to the technical field of discharge testers, in particular to a portable partial discharge tester. Background Art

[0002] A partial discharge detector is a test instrument used to detect partial discharge in high-voltage equipment. Partial discharge refers to discharge that occurs between electrodes but does not penetrate the electrodes. It is caused by weak electricity inside the insulation of the equipment or defects caused during the production process. Repeated breakdown and extinction occur under high electric field strength. The energy of this discharge is very small, and it does not affect the insulation strength of the electrical equipment in a short time. However, if partial discharges continue to occur in the insulation of electrical equipment under operating voltage, these weak discharges will have a cumulative effect, causing the dielectric properties of the insulation to gradually deteriorate and local defects to expand, eventually leading to the breakdown of the entire insulation. The function of a partial discharge detector is to detect the insulation status of power equipment and prevent insulation failure. , to ensure the safe operation of power equipment, it can detect partial discharge in the equipment, discover insulation defects in time and repair them, prevent equipment failure, extend equipment life, and improve the reliability and safety of the power system. The partial discharge detector has a wide range of uses and can be applied to the detection of various high-voltage equipment, such as transformers, switchgear, cables, busbars, etc. It can be used to detect the insulation status of new equipment, as well as the insulation status of old equipment, conduct equipment health assessment and maintenance decisions, and can also be used to monitor the operating status of the equipment to prevent equipment failure. In addition, the partial discharge detector can also be used to study the performance of high-voltage insulating materials and improve the quality and reliability of insulating materials.

[0003] The principles of partial discharge detectors mainly include high-frequency pulse current measurement method (ERA method) and ultrasonic detection method. The high-frequency pulse current measurement method is to detect the partial discharge pulse signal generated by the test product under the test voltage, send it to the input unit through the coupling capacitor, and the input unit picks up the pulse signal. After amplification by the low-noise preamplifier, the filter amplifier selects the required frequency band and the main amplifier amplifies it, the discharge waveform is displayed on the oscilloscope, or the discharge intensity is expressed by the apparent charge of the partial discharge on the digital instrument. The ultrasonic detection method detects the high-frequency noise generated by the partial discharge, and uses the "heterodyne method" to compile it into a sound signal audible to the human ear, so as to detect and locate the partial discharge. When using ultrasonic waves to detect the gaps in the metal cabinet, because the discharge position may be located deeper, when it propagates to the door gap, the intensity is relatively weak. At the same time, because the door gap is relatively narrow and long as a whole, when sampling the ultrasonic wave, it is necessary to sample the ultrasonic wave data in a larger range, and it is easy to collect noise, which is difficult to collect in a centralized manner. Summary of the invention

[0004] (I) Technical problems to be solved: In view of the deficiencies of the prior art, the present invention provides a portable partial discharge tester, which has the advantage of centralized sampling of ultrasonic signals, thus solving the problem that the tester needs to have a large sampling range and low sound wave intensity when sampling ultrasonic waves.

[0005] (II) Technical solution: To achieve the above-mentioned purpose of centralized sampling of ultrasonic signals, the present invention provides the following technical solution: a portable partial discharge tester, comprising a tester body, wherein a ground wave sensor and an ultrasonic detection head are arranged at the front end of the tester body. During partial discharge detection, the ground wave sensor contacts the metal cabinet surface, and the ultrasonic detection head is aligned with the gap at the cabinet door. The ground wave sensor and the ultrasonic sensor in the ultrasonic detection head work simultaneously. The surface array of the ultrasonic detection head has linearly arranged grid holes, and a timing control component and an ultrasonic sensor for controlling the opening and closing of the grid holes are arranged inside the ultrasonic detection head.

[0006] Preferably, the timing control component is specifically a shielding portion with a through hole, and the through hole is adapted to the size of the grid hole, so that the sound wave can only enter the ultrasonic detection head from the grid hole that coincides with the through hole on the timing control component. The timing control component is driven by a driving component to change the position of the through hole on the timing control component, and the ultrasonic wave can enter the ultrasonic detection head from different grid holes at different timings and be received by the ultrasonic sensor.

[0007] Preferably, the front end of the tester body is in a concave shape, the ultrasonic detection head is arranged in the middle, and the ground wave sensor is arranged at the protrusions on both sides of the ultrasonic detection head.

[0008] Preferably, the ultrasonic detection head is circular, and the grid holes are arranged in a radial array along the circumference.

[0009] Preferably, the timing control component is composed of a disk with through holes (i.e., the shielding portion) coaxially arranged with the ultrasonic detection head, the through holes are distributed in a spiral radial shape, and the driving component drives the disk to rotate.

[0010] Preferably, a buffer block for absorbing vibration is provided at the connection between the driving component and the timing control component. When the driving component is driven to rotate by the motor, a certain vibration will occur. The vibration will cause the components to collide directly and generate sound waves, which will have a certain impact on the ultrasonic waves collected by the grid hole. The buffer block absorbs part of the impact and vibration, thereby reducing the impact on the ultrasonic waves collected by the grid hole.

[0011] Preferably, the grid holes on the surface of the ultrasonic detection head are in a vertical array.

[0012] Preferably, the timing control component is specifically a strip with the through hole, and the driving component is specifically a winding component for winding the strip, the winding component is arranged at both ends of the timing control component, and the timing control component is made of flexible material. By changing the winding amount of the timing control component by the driving components at both ends, the position of the through hole on the timing control component relative to the gate hole is changed.

[0013] Preferably, a trumpet-shaped baffle ring is provided on the outside of the ultrasonic detection head, which can reduce the energy scattering and loss of ultrasonic waves during propagation, so that more energy is concentrated in the target area. This not only improves the detection distance of ultrasonic waves, but also makes the detection results more reliable. The baffle ring can also protect the detection head, which can prevent external objects from directly hitting the detection head, reduce the risk of damage, and extend the service life of the detection head.

[0014] Preferably, a sound insulation layer is provided on the inner wall of the ultrasonic detection head. The sound insulation layer can effectively reduce the interference of external noise on the internal circuit and sensor of the ultrasonic detection head. This noise reduction effect helps to improve the signal-to-noise ratio of the detection signal, making the detection result clearer and more accurate. By reducing noise interference, the sound insulation layer makes it easier for the ultrasonic detection head to capture weak ultrasonic signals, which helps to improve the detection sensitivity, so that the detection head can detect smaller or farther targets. The sound insulation layer can also protect the internal circuit and sensor of the ultrasonic detection head. It can prevent circuit damage or sensor failure caused by external noise or vibration, thereby improving the stability and reliability of the detection head.

[0015] (III) Beneficial effects: Compared with the prior art, the present invention provides a portable partial discharge tester, which has the following beneficial effects:

[0016] 1. The portable partial discharge tester has a plurality of grid holes at the front end of the ultrasonic detection head, and the grid holes are partially blocked by a timing control component. A through hole is provided on the timing control component, so that only the grid holes that coincide with the through hole positions on the timing control component can pass the sound wave. The timing control component is controlled by a driving component to change the position of the through hole on the timing control component, so that the grid holes through which the ultrasonic wave passes are changed, so that the ultrasonic wave enters different grid holes according to different timings, and the grid holes will form an array probe similar to that in a phased matrix. By adjusting the emission time of the ultrasonic wave on each array element (i.e., phase delay), the ultrasonic wave forms constructive interference in the same direction and destructive interference in other directions, and the main energy of the ultrasonic wave will be concentrated The ultrasonic wave propagates in a specific direction to achieve the deflection of the sound beam. In this way, the main energy of the ultrasonic wave will be focused on a specific point to achieve the focusing of the sound beam. The focusing effect can be achieved by changing the shape of the array, the distance between the array elements and the emission time delay. Through deflection and focusing, the ultrasonic wave with weak sound wave signals at the door gap and divergent directions will be gathered and collected by the ultrasonic sensor. Through the coordinated use of multiple grid holes and timing control components, the ultrasonic wave can enter different grid holes at different timings to form an array probe similar to that in a phased matrix. This design can effectively gather and enhance the ultrasonic signal. Especially when the sound wave signal at the door gap is weak and the direction is divergent, the focusing technology can significantly improve the detection sensitivity, making the ultrasonic The wave sensor can more easily capture weak sound wave signals. Since the ultrasonic energy can be concentrated in a specific direction, the detection sensitivity can be significantly improved through focusing technology even when the sound wave signal is weak or divergent in direction. The coordinated use of multiple grid holes and timing control components allows the ultrasonic wave to enter the sensor at different timings and paths, thereby increasing the chance and accuracy of detection. Since the ultrasonic energy is concentrated in a specific direction, the influence of noise and other interference factors in the surrounding environment on the detection results can be reduced. By adjusting the emission time of the ultrasonic wave on each array element (i.e., phase delay), the ultrasonic wave forms constructive interference in the same direction and destructive interference in other directions. This phased array The technology enables the main energy of ultrasound to be concentrated in a specific direction to propagate, thereby achieving the deflection of the sound beam. At the same time, by changing the shape of the array, the distance between array elements, and the emission time delay, the sound beam can be focused, focusing the ultrasonic energy on a specific point to improve the accuracy and resolution of detection. By adjusting the shape of the array, the distance between array elements, and the emission time delay and other parameters, the deflection and focusing effects of the sound beam can be optimized according to specific application requirements. This flexibility and configurability enable the ultrasonic detection head to adapt to different detection scenarios and requirements. When the ultrasonic wave enters different grid holes at different time sequences, each grid hole is equivalent to an array element. By adjusting the emission time of the ultrasonic wave on each array element (i.e., phase delay),Ultrasonic waves can form constructive interference in the same direction and destructive interference in other directions. In this way, the main energy of the ultrasonic wave will be concentrated in a specific direction to achieve the deflection of the sound beam. At the same time, by changing the shape of the array, the distance between the array elements and the transmission time delay, the sound beam can be focused to focus the ultrasonic energy on a specific point. This ultrasonic detection head design based on phased array technology enables ultrasonic waves to propagate and focus in a specific timing and direction, improving the sensitivity, accuracy and anti-interference ability of detection.

[0017] 2. The portable partial discharge tester contacts the cabinet surface through the ground wave sensor, and aims the ultrasonic detection head at the gap of the cabinet door for simultaneous detection. Ground wave detection and ultrasonic detection each have their own advantages and limitations. Ground wave detection is more suitable for electromagnetic wave signals transmitted through metal walls, while ultrasonic detection is better at detecting sound waves generated by discharge through gaps in the air or solids. Combining the two can cover a wider detection range and discharge type. Since the two sensors detect different signal types, they can capture different types of fault information respectively. Through simultaneous detection, we can have a more comprehensive understanding of the operating status and internal conditions of the switch cabinet, and improve the accuracy and completeness of the detection. The ground wave sensor and the ultrasonic detection head are based on different physical principles for detection. The ground wave sensor detects electromagnetic wave signals, which are generated by partial discharge inside the switch cabinet; while the ultrasonic detection head detects sound wave signals, which are generated by partial discharge inside the switch cabinet. Caused by physical defects or faults (such as cracks, looseness, etc.) inside the switch cabinet, compared with traditional single detection methods, simultaneous detection can significantly shorten the detection cycle and improve detection efficiency. This is especially important for scenarios that require rapid diagnosis and troubleshooting, such as switch cabinet detection in power systems. During the simultaneous detection process, the geoelectric wave sensor and the ultrasonic detection head can work at the same time without interfering with each other, which means that two different types of fault information can be collected at the same time within the same detection time. If the geoelectric wave sensor and the ultrasonic detection head detect an abnormality in the switch cabinet at the same time, it can be more certain that there is a problem with the equipment and take appropriate measures to deal with it. This helps to avoid false alarms and missed alarms and improve the accuracy and reliability of detection. When the two sensors detect abnormal signals at the same time, they can verify each other and improve the reliability of the detection results. This is because the fault information detected by different physical principles is independent of each other, but at the same time correlated.

[0018] 3. The portable partial discharge tester is provided with a trumpet-shaped baffle ring on the outside of the ultrasonic detection head. The trumpet-shaped baffle ring can reduce the energy scattering and loss of ultrasonic waves during the propagation process, so that more energy is concentrated in the target area, which not only improves the detection distance of ultrasonic waves, but also makes the detection results more reliable. The baffle ring can also protect the detection head. It can prevent external objects from directly hitting the detection head, reduce the risk of damage, and extend the service life of the detection head. A sound insulation layer is provided on the inner wall of the ultrasonic detection head. The sound insulation layer can effectively reduce the interference of external noise on the internal circuit and sensor of the ultrasonic detection head. This noise reduction effect helps to improve the signal-to-noise ratio of the detection signal, making the detection result clearer and more accurate. By reducing noise interference, the sound insulation layer makes it easier for the ultrasonic detection head to capture weak ultrasonic signals, which helps to improve the detection sensitivity, so that the detection head can detect smaller or farther targets. The sound insulation layer can also protect the internal circuit and sensor of the ultrasonic detection head, which can prevent circuit damage or sensor failure caused by external noise or vibration, and improve the stability and reliability of the detection head. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a schematic diagram of an ultrasonic testing head according to an embodiment of the present invention;

[0021] Figure 3 This is a cross-sectional view of an ultrasonic testing head according to a first embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of an ultrasonic testing head according to a second embodiment of the present invention;

[0023] Figure 5 This is a cross-sectional view of an ultrasonic testing head according to a second embodiment of the present invention;

[0024] Figure 6 This is a detailed schematic diagram of a driving component according to an embodiment of the present invention;

[0025] Figure 7 Schematic diagram of ultrasonic interference at different time sequences of the present invention Figure 1 ;

[0026] Figure 8 Schematic diagram of ultrasonic interference at different time sequences of the present invention Figure 2 ;

[0027] Fig. 9 This is a schematic diagram of a timing control component according to an embodiment of the present invention;

[0028] Fig.10 FIG. 1 is a schematic diagram of ultrasonic focusing according to an embodiment of the present invention.

[0029] In the figure: 1. Tester body; 11. Geomagnetic wave sensor; 12. Ultrasonic detection head; 121. Retaining ring; 122. Grid hole; 123. Timing control component; 124. Driving component; 125. Buffer block; 126. Ultrasonic sensor; 127. Sound insulation layer. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1: Please refer to Figure 1-Figure 3 and Figure 6 The portable partial discharge tester comprises a tester body 1, wherein a ground wave sensor 11 and an ultrasonic detection head 12 are arranged at the front end of the tester body 1. During partial discharge detection, the ground wave sensor 11 contacts the metal cabinet surface, and the ultrasonic detection head 12 is aligned with the gap at the cabinet door. The ground wave sensor 11 and the ultrasonic sensor 126 in the ultrasonic detection head 12 work simultaneously. The surface array of the ultrasonic detection head 12 has linearly arranged grid holes 122, and the ultrasonic detection head 12 is provided with a timing control component 126 for controlling the opening and closing of the grid holes 122. 3 and an ultrasonic sensor 126, the timing control component 123 is provided with a shielding portion with a through hole 120, the through hole is adapted to the size of the grid hole 122, so that the sound wave can only enter the ultrasonic detection head 12 from the grid hole 122 that coincides with the through hole on the timing control component 123, the timing control component 123 is driven by the driving component 124, so that the through hole on the timing control component 123 changes position, and the ultrasonic wave can enter the ultrasonic detection head 12 from different grid holes 122 at different timings and be received by the ultrasonic sensor 126.

[0032] The front end of the tester body 1 is in a concave shape, with the ultrasonic detection head 12 in the middle, and the ground wave sensor 11 is arranged at the protrusions on both sides of the ultrasonic detection head 12. Figure 6 and Fig. 9 The ultrasonic detection head 12 is circular, and the grid holes 122 are arranged radially along the circumference. The timing control component is composed of a disk with through holes 120 coaxially arranged with the ultrasonic detection head 12, and the through holes are distributed in a spiral radial shape. The driving component 124 drives the disk to rotate.

[0033] The driving component 124 is specifically a rotating shaft, and the timing control component 123 is in the shape of a disk and is driven to rotate by the driving component 124. The staff holds the tester body 1 and puts its front end close to the cabinet to be tested, and puts the ground wave sensor 11 in contact with the cabinet surface to ensure that there is good contact between the sensor and the metal wall. The ultrasonic detection head 12 is aimed at the gap at the cabinet door to ensure that the detection head can receive the ultrasonic signal leaked from the discharge area. Fig.10 , through the rotation of the timing control component 123, the through hole above it will also rotate accordingly, because the grid holes 122 are arranged along the radial circumference, so that the grid holes 122 of the array coincide with the through holes in sequence, and the grid holes 122 are opened and closed in sequence in the radial direction, and the ultrasonic wave is focused toward the center of the circle. The ultrasonic signal at the door gap will also enter the ultrasonic detection head 12 from the grid holes 122 at different positions at different timings as the timing control component 123 rotates. Because the ultrasonic wave will bounce back from the wall many times, the signal is weak. At the same time, the door gap is narrow and long, and the ultrasonic wave is divergent as a whole, which is difficult to be collected by the ultrasonic detection head 12. Therefore, a plurality of grid holes 122 are arranged at the front end of the ultrasonic detection head 12, and the grid holes 122 are partially blocked by the timing control component 123. The timing control component 123 is provided with a Through holes are arranged so that only the grid holes 122 that coincide with the positions of the through holes on the timing control component 123 can pass the sound waves. The timing control component 123 is controlled by the driving component 124 so that the positions of the through holes on the timing control component 123 are changed, so that the grid holes 122 through which the ultrasonic waves pass are changed, so that the ultrasonic waves enter different grid holes 122 according to different timings, and the grid holes 122 will form an array probe similar to that in a phased matrix. By adjusting the emission time of the ultrasonic waves on each array element (i.e., phase delay), the ultrasonic waves form constructive interference in the same direction and destructive interference in other directions. The main energy of the ultrasonic waves will be concentrated in a specific direction for propagation, so as to achieve the deflection of the sound beam. In this way, the main energy of the ultrasonic waves will be focused on a specific point, see Figure 7-Figure 8 By controlling the timing of ultrasonic waves passing through the grille holes 122, the ultrasonic waves are offset in the extension direction of the grille holes 122 to achieve the focusing of the sound beam. The focusing effect can be achieved by changing the shape of the array, the distance between array elements and the emission time delay. Through deflection and focusing, the ultrasonic waves with weak sound wave signals at the door gap and divergent directions are gathered and collected by the ultrasonic sensor 126, thereby improving the detection accuracy.

[0034] A buffer block 125 for absorbing vibration is provided at the connection between the driving component 124 and the timing control component 123. When the driving component 124 is driven to rotate by the motor, a certain vibration will occur. The vibration will cause the components to collide directly and generate sound waves, which will have a certain impact on the ultrasonic waves collected by the grid hole 122. The buffer block 125 absorbs part of the impact and vibration, thereby reducing the impact on the ultrasonic waves collected by the grid hole 122.

[0035] A trumpet-shaped baffle ring 121 is provided on the outside of the ultrasonic detection head 12. The trumpet-shaped baffle ring 121 can reduce the energy scattering and loss of ultrasonic waves during propagation, so that more energy is concentrated in the target area. This not only improves the detection distance of ultrasonic waves, but also makes the detection results more reliable. The baffle ring 121 can also protect the detection head, which can prevent external objects from directly hitting the detection head, reduce the risk of damage, and extend the service life of the detection head.

[0036] A sound insulation layer 127 is provided on the inner wall of the ultrasonic detection head 12. The sound insulation layer can effectively reduce the interference of external noise on the internal circuit and sensor of the ultrasonic detection head. This noise reduction effect helps to improve the signal-to-noise ratio of the detection signal, making the detection result clearer and more accurate. By reducing noise interference, the sound insulation layer makes it easier for the ultrasonic detection head to capture weak ultrasonic signals, which helps to improve the detection sensitivity, so that the detection head can detect smaller or farther targets. The sound insulation layer can also protect the internal circuit and sensor of the ultrasonic detection head. It can prevent circuit damage or sensor failure caused by external noise or vibration, and improve the stability and reliability of the detection head.

[0037] Example 2: Please refer to Figure 1 and Figure 4-Figure 5 A portable partial discharge tester comprises a tester body 1, wherein a ground wave sensor 11 and an ultrasonic detection head 12 are arranged at the front end of the tester body 1. During partial discharge detection, the ground wave sensor 11 contacts the metal cabinet surface, and the ultrasonic detection head 12 is aligned with the gap at the cabinet door. The ground wave sensor 11 and the ultrasonic sensor 126 in the ultrasonic detection head 12 work simultaneously. The surface array of the ultrasonic detection head 12 has grid holes 122, and a timing control component 123 is arranged inside the ultrasonic detection head 12. A single through hole is arranged on the timing control component 123, and the grid hole 122 is tightly attached to the timing control component 123, so that the sound wave can only enter the ultrasonic detection head 12 from the grid hole 122 that coincides with the through hole on the timing control component 123. The timing control component 123 is driven by a driving component 124 to change the position of the through hole on the timing control component 123, so that the sound wave can enter the ultrasonic detection head 12 from different grid holes 122 at different timings and be received by the ultrasonic sensor 126.

[0038] The front end of the tester body 1 is in a concave shape, with the ultrasonic detection head 12 in the middle, and the ground wave sensor 11 is arranged at the protrusions on both sides of the ultrasonic detection head 12. The grid holes 122 on the surface of the ultrasonic detection head 12 are in a vertical array. The timing control component 123 is specifically a strip with the through holes. The driving component 124 is specifically a winding component for winding the strip. The winding component is arranged at both ends of the timing control component 123. The timing control component 123 is made of flexible material. By changing the winding amount of the timing control component 123 by the driving components 124 at both ends, the position of the through hole on the timing control component 123 relative to the grid hole is changed. The staff holds the tester body 1 and places its front end close to the cabinet to be tested, and contacts the ground wave sensor 11 with the cabinet surface to ensure good contact between the sensor and the metal wall. The ultrasonic detection head 12 is aimed at the gap at the cabinet door to ensure that the detection head can receive the ultrasonic signal leaked from the discharge area. The timing control component 123 is reeled and released through the two-end driving components 124, so that the through hole on the timing control component 123 is translated between the two-end driving components 124, so that the ultrasonic wave can enter the ultrasonic detection head 12 from the grid holes 122 at different positions at different timings. Because the ultrasonic wave will bounce back from the wall many times, the signal is weak. At the same time, the door gap is narrow and long, and the ultrasonic wave is divergent as a whole, which is difficult to be collected by the ultrasonic detection head 12. Therefore, a plurality of grid holes 122 are set at the front end of the ultrasonic detection head 12, and the timing control component 123 partially blocks the grid holes 122, and a single through hole is provided on the timing control component 123, so that only the grid holes 122 that coincide with the through hole position on the timing control component 123 can pass the sound wave, and the timing control component 123 is controlled by the driving component 124, so that the through hole position on the timing control component 123 changes, so that the grid holes 122 through which the ultrasonic wave passes change, so that the ultrasonic wave enters different grid holes 122 according to different timings, and the grid holes 122 will form an array probe similar to that in a phased matrix, and by adjusting the emission time of the ultrasonic wave on each array element (i.e., phase delay), the ultrasonic wave forms a longitudinal interference in the same direction, and forms a destructive interference in other directions, and the main energy of the ultrasonic wave will be concentrated in a specific direction to propagate, so as to realize the deflection of the sound beam, so that the main energy of the ultrasonic wave will be focused on a specific point, see Figure 7-Figure 8 , realizing the focusing of the sound beam. The focusing effect can be achieved by changing the shape of the array, the distance between array elements and the emission time delay. Through deflection and focusing, the ultrasonic wave with weak sound wave signals at the door gap and divergent directions is gathered and collected by the ultrasonic sensor 126, thereby improving the detection accuracy.

[0039] A trumpet-shaped baffle ring 121 is provided on the outside of the ultrasonic detection head 12. The trumpet-shaped baffle ring 121 can reduce the energy scattering and loss of ultrasonic waves during propagation, so that more energy is concentrated in the target area. This not only improves the detection distance of ultrasonic waves, but also makes the detection results more reliable. The baffle ring 121 can also protect the detection head, which can prevent external objects from directly hitting the detection head, reduce the risk of damage, and extend the service life of the detection head.

[0040] A sound insulation layer 127 is provided on the inner wall of the ultrasonic detection head 12. The sound insulation layer can effectively reduce the interference of external noise on the internal circuit and sensor of the ultrasonic detection head. This noise reduction effect helps to improve the signal-to-noise ratio of the detection signal, making the detection result clearer and more accurate. By reducing noise interference, the sound insulation layer makes it easier for the ultrasonic detection head to capture weak ultrasonic signals, which helps to improve the detection sensitivity, so that the detection head can detect smaller or farther targets. The sound insulation layer can also protect the internal circuit and sensor of the ultrasonic detection head. It can prevent circuit damage or sensor failure caused by external noise or vibration, and improve the stability and reliability of the detection head.

[0041] Working principle: The staff holds the tester body 1 and puts its front end close to the cabinet to be tested, and contacts the ground wave sensor 11 with the cabinet surface to ensure good contact between the sensor and the metal wall. The ultrasonic detection head 12 is aimed at the gap at the cabinet door to ensure that the detection head can receive the ultrasonic signal leaked from the discharge area. When partial discharge occurs inside the high-voltage switch cabinet, it will be accompanied by the generation of electromagnetic waves. Since the metal wall of the switch cabinet is not completely closed, the electromagnetic waves will leak to the outside through gaps, holes and other structures. When the electromagnetic wave reaches the outer surface of the metal wall, it will induce a short voltage to the ground on the metal surface, that is, the transient ground voltage TEV. The sensor will sense the TEV signal generated when the electromagnetic wave generated by the partial discharge propagates on the metal wall. , these signals will be converted into electrical signals by the sensor and transmitted to the signal collector. When local discharge occurs, the medium around the discharge area will expand and contract rapidly, generating ultrasonic waves. These ultrasonic signals will propagate to the outside of the switch cabinet through the air or solid medium. Ultrasonic waves have directional characteristics and can accurately find the vibration source. The ultrasonic detection head will emit ultrasonic signals and receive ultrasonic signals reflected from the discharge area. These reflected signals will carry information about the discharge position. The processing unit will conduct a comprehensive analysis of the received signals, including the time difference, intensity, frequency and other characteristics of the signals. By comparing the results of the two detection methods, the location and intensity of the discharge point can be determined more accurately, because the ultrasonic detection head 12 is at the gap of the cabinet door. During detection, ultrasonic waves will bounce off the wall multiple times, resulting in a weak signal. At the same time, the door gap is long and narrow, and the ultrasonic waves are generally divergent, making it difficult to be collected by the ultrasonic detection head 12. Therefore, a plurality of grid holes 122 are provided at the front end of the ultrasonic detection head 12, and the grid holes 122 are partially blocked by the timing control component 123. A single through hole is provided on the timing control component 123, so that only the grid holes 122 that coincide with the through hole positions on the timing control component 123 can have sound waves pass through. The timing control component 123 is controlled by the driving component 124, so that the through hole positions on the timing control component 123 are changed, so that the grid holes 122 through which the ultrasonic waves pass are changed, so that the ultrasonic waves enter different grid holes 122 according to different timings, and the grid holes 122 will form an array probe similar to that in a phased matrix. By adjusting the emission time of the ultrasound on each array element (i.e., phase delay), the ultrasound forms constructive interference in the same direction and destructive interference in other directions. The main energy of the ultrasound will be concentrated in a specific direction to propagate, thereby achieving the deflection of the sound beam. In this way, the main energy of the ultrasound will be focused on a specific point to achieve the focusing of the sound beam. The focusing effect can be achieved by changing the shape of the array, the distance between the array elements, and the emission time delay. Through deflection and focusing, the ultrasound with weak sound wave signals at the door gap and divergent directions will be gathered and collected by the ultrasonic sensor 126, thereby improving the detection accuracy and reducing the interference of other sound wave signals on the detection.And the ground wave detection and ultrasonic detection are combined to achieve complementary detection.

[0042] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A portable partial discharge tester, comprising a tester body (1), characterized in that: The front end of the tester body (1) is provided with a geomagnetic wave sensor (11) and an ultrasonic detection head (12). During partial discharge detection, the geomagnetic wave sensor (11) contacts the metal cabinet surface, and the ultrasonic detection head (12) is aimed at the gap at the cabinet door. The geomagnetic wave sensor (11) and the ultrasonic sensor (126) in the ultrasonic detection head (12) work simultaneously. The surface array of the ultrasonic detection head (12) has linearly arranged grid holes (122). The ultrasonic detection head (12) is provided with a timing control component (123) for controlling the opening and closing of the grid holes (122) and an ultrasonic sensor. The timing control component (123) is a shielding portion with a through hole, the through hole being adapted in size to the grid hole (122), so that sound waves can only enter the ultrasonic detection head (12) from the grid hole (122) that coincides with the through hole on the timing control component (123), the timing control component (123) is driven by a driving component (124), so that the through hole on the timing control component (123) changes position, and ultrasonic waves can enter the ultrasonic detection head (12) from different grid holes (122) at different time sequences and be received by the ultrasonic sensor (126).

2. A portable partial discharge tester according to claim 1, characterized in that: The front end of the tester body (1) is in a concave shape, the ultrasonic detection head (12) is arranged in the middle, and the ground wave sensors (11) are arranged at the protrusions on both sides of the ultrasonic detection head (12).

3. A portable partial discharge tester according to claim 1, characterized in that: The ultrasonic detection head (12) is circular, and the grid holes (122) are arranged in a radial array along the circumference.

4. A portable partial discharge tester according to claim 3, characterized in that: The timing control component is composed of a disk with through holes (120) arranged coaxially with the ultrasonic detection head (12), the through holes being distributed in a spiral radial shape, and the driving component (124) drives the disk to rotate.

5. A portable partial discharge tester according to claim 4, characterized in that: A buffer block (125) for absorbing vibration is provided at the connection between the driving component (124) and the timing control component (123).

6. A portable partial discharge tester according to claim 1, characterized in that: The grid holes (122) on the surface of the ultrasonic detection head (12) are arranged in a vertical array.

7. A portable partial discharge tester according to claim 3, characterized in that: The timing control component (123) is a strip with the through hole, the driving component (124) is a winding component for winding the strip, the winding components are arranged at two ends of the timing control component (123), the timing control component (123) is made of a flexible material, and the position of the through hole on the timing control component (123) relative to the grid hole is changed by changing the winding amount of the driving components (124) at both ends of the timing control component (123).

8. A portable partial discharge tester according to any one of claims 1 to 7, characterized in that: A trumpet-shaped retaining ring (121) is provided on the outer side of the ultrasonic detection head (12).

9. A portable partial discharge tester according to any one of claims 1 to 7, characterized in that: A sound insulation layer (127) is provided on the inner wall of the ultrasonic detection head (12).

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