Device and method for testing reliability of optical microphone by simulating oil pressure

Abstract

The invention relates to a reliability device for testing an optical microphone by simulating oil pressure and a testing method, and belongs to the technical field of optical sensor testing. The device mainly comprises a test box, an oil conservator, an air pressure system, a pressure control system and an ultrasonic signal generation system. The test box is pressurized through the blast pump and the oil conservator, and oil pressure environments at different depths in the transformer are accurately simulated by using a plurality of pressure release valves with different pressure thresholds. According to the invention, not only can the sensitivity and the minimum sensing amount of the optical microphone under different static oil pressures be tested, but also fatigue life evaluation can be carried out through controllable pressure circulation. The device has the advantages that the oil pressure control is accurate, the range is wide, the safety is high, the functions of vacuum simulation, ultrasonic excitation and the like are integrated, and a key test means is provided for model selection, point distribution and reliability evaluation of the optical microphone in the oil-immersed transformer.

Description

Technical Field

[0001] This invention relates to the field of optical sensor testing technology, and in particular to a device and method for simulating oil pressure to test the reliability of an optical microphone. Background Technology

[0002] Partial discharge is a discharge phenomenon that occurs when there are minute defects in the internal insulation material of a transformer, and it is an important indicator of transformer insulation deterioration. If it is not monitored and addressed in a timely manner, it may eventually lead to insulation breakdown and cause a major power accident. Therefore, partial discharge detection in transformers is of great significance.

[0003] Fabry-Pérot (FP) fiber optic sensors are widely used in the ultrasonic detection of partial discharge in power equipment such as transformers and GIS (Gas Insulated Switchgear) due to their advantages such as high sensitivity, low transmission loss, strong resistance to electromagnetic interference, and fast dynamic response. These sensors are often referred to as optical microphones.

[0004] In practical applications, optical microphones are typically installed at different depths inside oil-immersed transformers. Due to the varying depths of the transformer oil, the static oil pressure experienced by the optical microphone also differs. This high-pressure environment significantly impacts the detection performance and long-term reliability of the optical microphone: First, high oil pressure can cause plastic deformation of the reflective diaphragm in the FP cavity, altering the microphone's cavity length, leading to a shift in the sensor's operating point, measurement errors, and decreased sensitivity. If the diaphragm material lacks sufficient compressive strength, it may even rupture or undergo permanent deformation, resulting in device failure. Second, the high-pressure environment amplifies potential defects in the optical microphone's packaging structure, potentially allowing transformer oil to seep into the microphone's cavity. This not only interferes with the optical path but may also corrode internal components, reducing long-term reliability. Furthermore, under high oil pressure, molecules in the transformer oil may adsorb onto the reflective diaphragm surface, altering its optical properties and affecting the microphone's sensitivity. Additionally, the high oil pressure environment causes deformation and stress in the microphone's concave diaphragm, making it difficult to vibrate when sensing ultrasonic signals, thus reducing the microphone's sensitivity and minimum sensing threshold.

[0005] Therefore, there is an urgent need to conduct reliability tests on optical microphones under high oil pressure conditions in order to scientifically evaluate the performance variation and service life of optical microphones under different oil pressure conditions. However, at present, there is a lack of dedicated equipment and systematic testing schemes that can highly simulate the oil pressure environment at different depths inside transformers, quantitatively test key parameters such as sensitivity and minimum sensing quantity of optical microphones, and conduct fatigue life assessments. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: in order to overcome the above-mentioned technical problems, the present invention provides a device and method for simulating oil pressure to test the reliability of an optical microphone.

[0007] The technical solution adopted by the present invention to solve its technical problem is: the present invention provides a device for simulating oil pressure to test the reliability of an optical microphone, comprising: a test box, an oil tank and an ultrasonic signal generation system.

[0008] The test box contains a test platform for fixing an optical microphone. The test box is equipped with a through-hole interface, which contains a through-hole for introducing the optical microphone signal line, enabling the optical microphone to be installed in a recessed manner. This fixes the optical microphone on the test platform and prevents it from being moved by the transformer oil flow during oil filling. The bottom of the box is equipped with a transformer oil inlet and a transformer oil outlet, which, together with the oil pump, enable the rapid replacement of transformer oil inside the device.

[0009] An oil conservator, connected to the test chamber, provides pressure regulation space for the entire device. The oil conservator is equipped with a pneumatic system and a pressure control system. The pneumatic system includes an inlet valve, an exhaust valve, and an air pump. The inlet and exhaust valves are located on the oil conservator. The inlet valve, connected to the air pump, applies air pressure to the inside of the oil conservator, while the exhaust valve releases pressure inside the conservator. The inlet valve, connected to the air pump, enables rapid pressurization of the device, and the exhaust valve rapidly releases pressure, completing one pressurization cycle. The pressure control system includes pressure relief valves. Multiple pressure relief valves with different pressure thresholds are located on the oil conservator. A row of pressure relief valves of different specifications is located on the top of the oil conservator. Controlling the opening and closing of these valves allows for the simulation of transformer oil pressure values ​​at different depths, enabling testing of the optical microphone.

[0010] The pass-through includes a housing, an optical fiber transmission assembly, and a quick-install sealing mechanism. The housing has cavities extending through both ends. The optical fiber transmission assembly includes an optical fiber patch cord and a potting compound. The patch cord passes through the cavity, and the potting compound is located within the cavity and seals the patch cord within it. The optical microphone signal line is connected to the patch cord of the pass-through. The quick-install sealing mechanism is mounted on the housing and is used to detachably fix the housing to the adapter plate of the oil-immersed transformer and achieve a seal. The quick-install sealing mechanism includes a movable rod, a connecting rod, and at least two openable spring clips. The movable rod is movably mounted on the housing along its axial direction. The spring clips are linked to the movable rod via the connecting rod. When the movable rod is pushed inwards towards the transformer, the spring clips close to allow the pass-through to pass through the adapter plate. When the movable rod is pulled outwards towards the transformer, the movable rod moves outwards towards the transformer, and the connecting rod causes the spring clips to open and press tightly against the inner wall of the transformer, achieving a compression seal.

[0011] An ultrasonic signal generating system includes a high-voltage sleeve for applying a high-voltage signal and a discharge model for generating ultrasonic signals. The high-voltage sleeve is located on the top of the test chamber, and the discharge model is connected to the bottom of the high-voltage sleeve. The high-voltage sleeve is installed on the top of the test chamber, thereby applying high-voltage signals of different voltage levels in conjunction with various discharge models connected to the bottom of the high-voltage sleeve to generate ultrasonic signals, thereby testing the sensitivity and signal-to-noise ratio of the optical microphone.

[0012] By pressurizing the air pump and controlling the opening and closing of different pressure relief valves, the oil pressure environment at different depths inside the transformer can be simulated to test the performance parameters of the optical microphone under different oil pressures.

[0013] The pressure control system also includes a vacuum pump connected to the oil tank, which is used to evacuate the inside of the oil tank to simulate the vacuum environment inside the test chamber before the transformer is filled with oil.

[0014] The pressure control system also includes a pressure gauge connected to the oil tank, which is used to display the internal pressure of the device in real time and assist in the precise adjustment of the internal pressure of the device.

[0015] The multiple pressure relief valves with different pressure thresholds are 0.02 MPa, 0.1 MPa, 0.2 MPa and 0.4 MPa, respectively, so that the test chamber can simulate the transformer oil pressure environment at depths of 1 meter, 5 meters, 10 meters and 20 meters.

[0016] The pressure control system also includes a safety valve located in the oil tank. The safety valve is normally open and serves as the highest level of protection against overpressure, preventing damage to the equipment caused by excessive internal pressure.

[0017] The ultrasonic signal generation system also includes a function generator and a power amplifier. The function generator is electrically connected to the discharge model through the power amplifier. The host computer controls the function generator to output sinusoidal signals of the same voltage level but different frequencies, and applies high voltage to the discharge model through the power amplifier.

[0018] The discharge model is a replaceable structure used to simulate different types of partial discharge defects.

[0019] This invention provides a method for simulating oil pressure testing of the reliability of an optical microphone, based on the aforementioned apparatus, comprising the following steps: Step 1: Fix the optical microphone on the test platform and lead its signal cable out of the test box through a connector. The optical microphone's signal cable is made of optical fiber, which is led out using a connector to connect to an external demodulation system. Step 2: Pour transformer oil into the test chamber until the optical microphone is submerged; Step 3: Control the ultrasonic signal generating system to generate ultrasonic signals, and test and record the initial performance parameters of the optical microphone under normal atmospheric pressure; Step 4: Open the air inlet valve and start the air pump to pressurize the device; Step 5: Open a pressure relief valve with a pressure threshold to stabilize the internal pressure of the device at the pressure threshold corresponding to the pressure relief valve. Step 6: Under the pressure generated in step 5, control the ultrasonic signal generating system to generate an ultrasonic signal with the same voltage level as in step 3, and test and record the performance parameters of the optical microphone under the current pressure. Step 7: Open the pressure relief valves with different pressure thresholds, and repeat steps 5-6 to obtain the performance parameters of the optical microphone under different pressure values; Step 8: Based on the recorded data, analyze the influence of oil pressure on the performance parameters of the optical microphone.

[0020] When the pressure control system includes an air pump, it includes the step of simulating the internal vacuum environment during transformer oil drainage, including: the air pump is connected to the oil tank, the air pump is used to extract the air from the inside of the device, and the pressure inside the device is detected in real time by an air pressure detection instrument.

[0021] The performance parameters include the sensitivity and minimum sensing quantity of the optical microphone.

[0022] In step 6, the performance parameters of the optical microphone at different frequencies are tested by changing the frequency of the ultrasonic signal.

[0023] This invention provides a method for assessing the fatigue life of an optical microphone, based on the aforementioned device, comprising the following steps: Step 1: Fix the optical microphone on the test platform and lead its signal cable out of the test box through a connector. The optical microphone's signal cable is made of optical fiber, which is led out using a connector to connect to an external demodulation system. Step 2: Pour transformer oil into the test chamber until the optical microphone is submerged; Step 3: Control the ultrasonic signal generating system to generate ultrasonic signals; Step 4: Open a pressure relief valve with a pressure threshold, which is the maximum oil pressure value of this oil pressure cycle; Step 5: Open the air intake valve and pressurize the device at a constant rate using the air pump until the internal pressure of the device reaches the maximum oil pressure value. Then, open the pressure relief valve in Step 4 to release the pressure inside the device to normal atmospheric pressure, completing one oil pressure cycle. Step 6: Repeat the hydraulic circulation of step 5 a predetermined number of times; Step 7: After each predetermined number of cycles, test and record the performance parameters of the optical microphone; Step 8: Plot the performance parameters of the optical microphone as a function of the number of hydraulic cycles to assess its fatigue life.

[0024] The predetermined number of cycles is 500.

[0025] Compared with the prior art, the apparatus and test scheme for simulating oil pressure to test the reliability of optical microphones provided by the present invention have the following significant advantages: 1. This invention uses an oil-gas mixed pressurization method, which can simulate the oil pressure values ​​experienced by an optical microphone at different depths using only a small amount of transformer oil. By using a pressure gauge and an air pump, the oil pressure can be precisely controlled, achieving high-precision oil pressure simulation. Simultaneously, the device utilizes an air pump to achieve a negative pressure state, simulating the internal vacuum environment of a large oil-immersed transformer during oil drainage, thus realizing a pressure range from negative to high oil pressure and meeting the testing requirements for oil pressure values ​​at different depths of the optical microphone.

[0026] 2. The oil tank is equipped with pressure relief valves of different specifications. When the internal pressure reaches the preset threshold, it can automatically open to relieve pressure, effectively preventing excessive pressure from damaging the device and sensors. In addition, a safety valve is installed on the top of the oil tank, which is in a normally open state to protect the equipment at all times, avoiding damage to the device due to excessive internal pressure, and ensuring the safety and reliability of the test process.

[0027] 3. The device of this invention integrates functions such as hydraulic simulation, vacuum simulation, ultrasonic signal excitation, and multi-sensor synchronous testing. It can not only test the performance parameters of optical microphones such as sensitivity and minimum sensing quantity under different static hydraulic pressures, but also conduct fatigue life tests under repeated hydraulic cycles, thus completing a comprehensive evaluation of the reliability of optical microphones in one stop.

[0028] 4. This invention directly addresses the practical needs of partial discharge detection in oil-immersed power transformers. The test data and evaluation conclusions provided can directly provide theoretical basis and practical guidance for the installation depth of optical microphones inside the transformer, effectively avoiding monitoring blind spots caused by sensor failure under high oil pressure. It has important practical application value for ensuring the safe and stable operation of power transformers.

[0029] 5. The fatigue life assessment method proposed in this invention, based on the device, can perform a certain number of pressure cycles on optical microphones, especially those with more fragile diaphragm groove-shaped structures, by controlling the pressurization rate and maximum cyclic pressure, and monitor their performance degradation. This quantitatively assesses the impact of the number of hydraulic cycles on the sensor's lifespan, providing crucial data support for the selection, placement depth design, and expected service life of optical microphones. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the device for simulating oil pressure to test the reliability of an optical microphone provided in an embodiment of the present invention.

[0031] Figure 2 This is a flowchart of a method for simulating oil pressure to test the reliability of an optical microphone, provided in an embodiment of the present invention.

[0032] Figure 3 This is a flowchart of the optical microphone fatigue life assessment method provided in the embodiments of the present invention.

[0033] Figure 4 This is a schematic diagram of the overall structure of the penetrator provided in an embodiment of the present invention.

[0034] Figure 5 This is a partially enlarged schematic diagram of the fiber optic patch cord encapsulated within the housing in this invention.

[0035] Figure 6 This is a schematic diagram of the installation process of the penetrator provided in an embodiment of the present invention.

[0036] In the diagram: 1. Test box; 2. Oil tank; 3. Inlet valve; 4. Exhaust valve; 5. Pressure relief valve; 6. Safety valve; 7. High-voltage bushing; 8. Discharge model; 9. Optical microphone; 10. Optical microphone signal line; 11. Test platform; 12. Transformer oil inlet / outlet; 13. Through-connector; T1. Fiber optic patch cord; T2. Fiber optic interface; T3. Flange; T4. Inner sleeve; T41. Encapsulation body; T5. Outer shell; T6. Adapter plate; T7. Spring; T8. Pivot point; T9. Connecting ring; T10. Push rod; T11. Connecting rod; T12. Sealing ring; T13. Thread; T14. Fixing nut; T15. Return spring; T16. Locking block; a. Transformer inner side. Detailed Implementation

[0037] The invention will now be described in further detail with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and not intended to limit the scope or application of the invention.

[0038] like Figure 1 As shown in the figure, an embodiment of the present invention provides a device for simulating oil pressure testing of the reliability of an optical microphone, including a test chamber 1, an oil tank 2, and an ultrasonic signal generation system.

[0039] The test chamber 1 contains a test platform 11 for fixing optical microphones 9. A through-hole interface is provided on the side wall of the test chamber 1, and a through-hole 13 is installed inside the through-hole interface to introduce the optical microphone signal line 10, enabling the insertion and installation of the optical microphone 9. The device can include multiple through-hole interfaces, allowing for the simultaneous insertion and installation of multiple optical microphones 9, enabling large-scale repeated testing. The optical microphones 9 are fixed on the test platform 11 to prevent movement due to the impact of transformer oil flow during oil filling. The bottom of the chamber has a transformer oil inlet and a transformer oil outlet, which, together with the oil pump, allows for rapid replacement of the transformer oil inside the device. Figure 1 The location shown in Figure 12 is the transformer oil inlet or outlet. The transformer oil inlet and outlet are located on the same side, but they are separate.

[0040] Oil conservator 2, connected to test chamber 1, provides pressure regulation space for the entire device. Oil conservator 2 is equipped with a pneumatic system and a pressure control system. The pneumatic system includes an inlet valve 3, an exhaust valve 4, and an air pump. Inlet valve 3 and exhaust valve 4 are located on the top of oil conservator 2. Inlet valve 3 is connected to the air pump to apply air pressure to the inside of oil conservator 2, while exhaust valve 4 is used to release pressure inside oil conservator 2. Inlet valve 3, connected to the air pump, enables rapid pressurization of the device's interior, while exhaust valve 4 is used to rapidly release pressure, completing one pressurization cycle. The pressure control system includes pressure relief valves 5. Multiple pressure relief valves 5 with different pressure thresholds are installed on oil conservator 2. A row of pressure relief valves 5 of different specifications is located on the side of oil conservator 2. Controlling the opening and closing of these valves allows for the simulation of transformer oil pressure values ​​at different depths, thus enabling the testing of optical microphone 9.

[0041] An ultrasonic signal generating system includes a high-voltage sleeve 7 for applying high-voltage signals of different voltage levels and a discharge model 8 for generating ultrasonic signals. The high-voltage sleeve 7 is located on the top of the test chamber 1, and the discharge model 8 is connected to the bottom of the high-voltage sleeve 7. The high-voltage sleeve 7 is a conventional small sleeve, mainly used to connect an external voltage generator to apply voltage to the internal discharge model. The high-voltage sleeve 7 is installed on the top of the test chamber 1, thereby applying high-voltage signals of different voltage levels in conjunction with various discharge models 8 connected to the bottom of the high-voltage sleeve 7 to generate ultrasonic signals, thereby testing the sensitivity and signal-to-noise ratio of the optical microphone 9.

[0042] By pressurizing the air pump and controlling the opening and closing of different pressure relief valves 5, the oil pressure environment at different depths inside the transformer can be simulated to test the performance parameters of the optical microphone 9 under different oil pressures.

[0043] The pressure control system also includes a vacuum pump, which is connected to the oil tank 2 and is used to evacuate the inside of the oil tank 2, so that the inside of the test chamber 1 simulates the vacuum environment before the transformer is filled with oil.

[0044] The pressure control system also includes a pressure gauge connected to the oil tank 2, which is used to display the internal pressure of the device in real time and assist in the precise adjustment of the internal pressure of the device.

[0045] Multiple pressure relief valves 5 with different pressure thresholds of 0.02 MPa, 0.1 MPa, 0.2 MPa and 0.4 MPa are used to simulate the transformer oil pressure environment at depths of 1 meter, 5 meters, 10 meters and 20 meters inside the test chamber 1, respectively.

[0046] The pressure control system also includes a safety valve 6 located at the top center of the oil tank 2. The safety valve 6 is normally open and serves as the highest level of protection against overpressure, preventing damage to the equipment caused by excessive internal pressure.

[0047] The ultrasonic signal generation system also includes a function generator and a power amplifier. The function generator is electrically connected to the discharge model 8 via the power amplifier. A host computer controls the function generator to output sinusoidal signals of the same voltage level but different frequencies, which are then applied to the discharge model 8 via the power amplifier. Because the voltage level of the function generator is relatively low, a power amplifier is connected after it. The host computer, or computer, can control any waveform input to the function generator, which is then applied to the discharge model 8 by the power amplifier to simulate a discharge.

[0048] Discharge model 8 is a replaceable structure used to simulate different types of partial discharge defects. The discharge model can be a needle-plate discharge model, a ball-plate discharge model, or a plate-plate discharge model. The lower end of the discharge model is fixed inside the device via a frustum. The upper end inside the device is connected to the electrodes of the discharge model via a screw. The threaded connection between the frustum and the screw facilitates electrode replacement. The screw is connected to a function generator to control the electrodes to generate corresponding partial discharge signals.

[0049] like Figure 2As shown, to test the effect of transformer oil pressure on the reliability of optical microphone 9, the optical microphone 9 was first fixed to the test platform. The optical microphone signal line 10 (i.e., fiber optic cable) was led out of the test box 1 and connected to an external demodulation system using a connector 13. Transformer oil was injected into the device through the transformer oil inlet until the optical microphone 9 was submerged. A host computer controlled a function generator to output sinusoidal signals of the same voltage level but different frequencies. High voltage was applied to the high-voltage bushing 7 through a power amplifier. The bottom of the high-voltage bushing 7 had various replaceable discharge models 8 that generated ultrasonic signals. The generated ultrasonic signals were used to test the sensitivity of the optical microphone 9 and the minimum frequency at which it sensed the ultrasonic signal. The test was repeated multiple times, and the data was recorded. The 0.02 MPa pressure relief valve 5 was opened, and an air pump was used to apply air pressure to the inside of the device. When the air pressure reached 0.02 MPa, the pressure relief valve 5 automatically opened. This simulated the transformer oil pressure at a depth of 1 m. Then, sinusoidal signals of the same voltage level but different frequencies (without oil pressure) were applied to the high-voltage bushing 7. The sensitivity of the optical microphone 9 and the minimum frequency at which it sensed the ultrasonic signal were tested at this time. The test was repeated multiple times, and the data was recorded. Similarly, the effect of oil pressure values ​​at depths of 5m, 10m, and 20m on the detection performance of the optical microphone 9 can be simulated by opening four pressure relief valves 5 of different specifications (0.1MPa, 0.2MPa, and 0.4MPa) and repeating the above operation. The test data can be plotted as sensitivity-oil pressure and minimum sensing quantity-oil pressure curves to quantitatively analyze the impact of oil pressure values ​​at different depths on the test performance of the optical microphone 9, providing a reference for the placement depth of the optical microphone 9. Here, the pressure relief valve must first be kept open; once the set pressure value is reached, the pressure relief valve will automatically open.

[0050] For the recessed optical microphone 9, because its resonant cavity diaphragm is thinner, repeated hydraulic cycles cause diaphragm fatigue, reducing its sensitivity to vibrations when sensing ultrasonic signals and shortening the lifespan of the optical microphone 9. For example... Figure 3As shown in the figure, an embodiment of the present invention provides a fatigue life assessment method for an optical microphone. Based on the testing device of the present invention, the long-term reliability of the optical microphone is evaluated. The specific operation steps are as follows: The 0.02 MPa pressure relief valve 5 is opened to simulate the oil pressure value at a depth of 1 m. This is the maximum oil pressure value in the oil pressure cycle. An air pump is used to control the pressurization at the same rate. When the maximum air pressure inside the device is reached, that is, when the simulated maximum oil pressure value is reached, the pressure relief valve 5 automatically opens. At this time, the air inlet valve 3 and the air pump stop working, restoring the air pressure inside the device to normal atmospheric pressure, which constitutes one oil pressure cycle. The sensitivity of the optical microphone 9 and the lowest frequency at which it senses an ultrasonic signal are tested every 500 oil pressure cycles. Multiple sets of repeated tests are conducted, and data are recorded to evaluate the impact of the number of oil pressure cycles on the service life of the optical microphone 9. The predetermined number of cycles here is 500, which is selected based on experience to shorten the experimental time while obtaining test data. It can also be adjusted according to actual conditions. Similarly, open the pressure relief valves 5 of four specifications (0.1 MPa, 0.2 MPa, and 0.4 MPa) to change the maximum oil pressure value of the maximum oil pressure cycle, and apply air pressure at the same pressurization rate. Test the sensitivity and minimum sensing intensity of the optical microphone 9 every 500 oil pressure cycles and record the data. Plot the sensitivity-oil pressure cycle count, minimum sensing intensity-oil pressure cycle count, and oil pressure cycle count-maximum cycle oil pressure curves to quantify the impact of the cycle count and maximum cycle oil pressure value on the long-term reliability of the optical microphone 9, providing a reference for the service life of the optical microphone 9 at different deployment depths. The minimum sensing intensity of the optical microphone 9 is determined by first placing all the devices in a fixed position, then slowly applying voltage. The applied voltage value is the minimum sensing intensity when the sensor responds. The sensitivity test principle is similar: within the range that the sensor can detect, change the voltage amplitude and observe the range of changes in the sensor's output. The number of oil pressure cycles is the number of times the experiment is repeated. Use an air pump to apply air pressure to the inside of the device, increase the internal pressure, maintain it for a period of time, and then release the pressure, repeating this process continuously.

[0051] like Figure 4As shown, the penetrator 13 provided in this embodiment of the invention includes a housing, an optical fiber transmission assembly, and a quick-install sealing mechanism. The housing has an accommodating cavity extending through both ends; the optical fiber transmission assembly includes an optical fiber patch cord T1 and a potting compound T41. The optical fiber patch cord T1 penetrates the accommodating cavity and transmits the sensor's detection signal to an external demodulation system with low optical loss, thereby realizing the transmission of optical signals. The potting body T41 is located within the accommodating cavity and pots the fiber optic patch cord T1 within the accommodating cavity. The optical microphone signal line 10 is connected to the fiber optic patch cord T1 of the pass-through device 13. A quick-install sealing mechanism is provided on the housing and is used to detachably fix the housing to the adapter plate T6 of the oil-immersed transformer and achieve sealing. The quick-install sealing mechanism includes a movable rod, a connecting rod T11, and at least two openable spring pieces T7. The movable rod is movably disposed on the housing along the axial direction of the housing. The spring pieces T7 are linked to the movable rod through the connecting rod T11. When the movable rod is pushed inward toward the transformer, the spring pieces T7 are closed to allow the pass-through device to pass through the adapter plate T6. When the movable rod is pulled outward toward the transformer, the movable rod moves in the direction of the transformer's outward direction, and the connecting rod T11 drives the spring pieces T7 to open and press tightly against the inner wall of the transformer to achieve a compression seal.

[0052] The fiber optic interface T2 of the fiber optic patch cord T1 is preferably an FC type interface to avoid the interface being too long and protruding, causing partial discharge inside the transformer.

[0053] like Figure 5 As shown, the potting height of the potting body T41 is flush with the end face of the outer shell, ensuring high sealing performance inside the connector 13. During potting, potting is performed on both sides of the flange T3 of the FC type interface to facilitate connection with the optical fiber. The potting body T41 is made of high-temperature and oil-resistant epoxy resin. When forming the potting body T41, silicone is first used to pre-fix the optical fiber patch cord T1 to maintain its shape, and then epoxy resin potting is performed to avoid excessive bending and excessive compression of the optical fiber patch cord T1 during epoxy resin condensation and curing, which would increase optical loss.

[0054] The quick-install sealing mechanism also includes a sealing ring T12 and a fixing nut T14. When the spring T7 opens and is pressed against the inner wall of the transformer, the sealing ring T12 is compressed between the adapter plate T6 and the outer shell and / or between the adapter plate T6 and the fixing nut T14. The fixing nut T14 is sleeved on the outer shell and threadedly connected to the outer shell.

[0055] The ferrule of the fiber optic patch cord T1 is preferably a glass ferrule, and the outer surface of the glass ferrule is covered with a titanium dioxide coating. The titanium dioxide coating is formed on the surface of the glass ferrule by spraying or vapor deposition.

[0056] The outer casing includes an inner sleeve T4 and an outer shell T5 coaxially fitted together, with a gap between the inner sleeve T4 and the outer shell T5. The movable rod and connecting rod 11 are disposed within the gap, and the potting body T41 is enclosed within the inner sleeve T4. Both the inner sleeve T4 and the outer shell T5 are made of stainless steel. The gap between the inner sleeve T4 and the outer shell T5 is filled with air to facilitate the sliding of the movable rod, thereby controlling the opening state of the spring T7.

[0057] The movable rod includes a connecting ring T9 and multiple push rods T10. The push rods T10 are arranged along the axial direction of the outer shell and are evenly distributed between the inner sleeve T4 and the outer shell T5. The connecting ring T9 is located at the end away from the spring T7, and one end of each push rod T10 is connected to one end of the spring T7 via a connecting rod T11. The other end of each push rod T10 is fixedly connected to the connecting ring T9. The outer shell is also provided with a locking assembly, which includes a return spring T15 and a locking block T16. One end of the return spring T15 is fixed to the inner sleeve T4, and the other end of the return spring T15 is fixed to the locking block T16. The return spring T15 is arranged perpendicular to the axial direction of the outer shell. The locking block T16 moves radially along the outer shell through the return spring T15. When the movable rod is pulled outward towards the outside of the transformer, the spring T7 opens and presses tightly against the inner wall of the transformer. The locking block T16 pushes the inner wall of the connecting ring T9 outward and locks with the connecting ring T9, thereby locking the push rod T10. In this embodiment, the connecting ring T9 is a circular ring shape, which is fitted onto the optical fiber connector. The connecting ring T9 and the push rod T10 are a whole.

[0058] like Figure 6 As shown, the push rod T10 moves to the left, causing the spring piece T7 to move and close, making it easier for the penetrator to pass through the adapter plate T6 and enter the transformer. Then, the connecting ring T9 is stretched to the right, pulling the push rod T10. The connecting rod T11 causes the spring piece T7 to move and open. The entire penetrator is moved to the right to ensure that the spring piece T7 is tightly attached to the inner wall of the transformer. The rubber sealing ring T12 is used to ensure a seal, and the fixing nut T14 is tightened to fix the penetrator and complete the installation.

[0059] Existing transformer oil pressure simulation devices have low accuracy and cannot accurately simulate oil pressure values ​​at different depths inside a transformer. The device of this invention uses an oil conservator 2 with added air pressure to simulate oil pressure values ​​at different depths. Combined with an air pressure system and a pressure control system, the air pressure is flexibly adjusted to achieve precise oil pressure control. The top of the oil conservator 2 contains four types of pressure relief valves 5. When the internal pressure reaches its pressure threshold, the pressure relief valve 5 automatically opens to prevent excessive internal pressure from damaging the device, achieving a stepped protection mechanism. This high-precision oil pressure control method allows for testing the sensitivity and minimum sensing intensity of the optical microphone 9 under precise oil pressure values, obtaining more accurate sensitivity and minimum sensing intensity-oil pressure curves, providing a reference for the detection offset of the optical microphone 9 at different placement depths.

[0060] The top of the oil conservator 2 can be connected to an air pump to perform a vacuum operation inside the device, simulating the vacuum environment inside an oil-immersed transformer during oil filling. This prevents air from mixing into the insulating oil, forming tiny bubbles that can cause partial discharge, interfere with the testing of the optical microphone 9, and lead to insulation degradation. It creates a wide range of atmospheric pressure environments, from vacuum to high pressure, enabling reliability assessment of the optical microphone across the entire pressure range. Specifically, the device is first kept well-sealed, and then the air inside is extracted using the air pump. A pressure measuring instrument on the top of the device can monitor the internal pressure in real time.

[0061] The hydraulic pressure environment not only affects the sensitivity of the optical microphone 9, but also causes mechanical damage to its reflective diaphragm. This is especially true for recessed optical microphones, where the thinner diaphragm leads to greater damage. Therefore, based on this device, an optical microphone lifespan assessment test was conducted. The same pressurization rate was controlled, and the pressure relief valve was opened to ensure the same maximum circulating pressure when the same air pressure was reached. Then, the next air pressure cycle was initiated. Sensitivity and minimum perceived quantity tests were performed on the optical microphone 9 every 500 cycles. Data was recorded, and sensitivity / minimum perceived quantity versus cycle count curves were plotted to quantify the damage to the diaphragm caused by the number of cycles, providing a reference for the long-term reliability of the optical microphone.

[0062] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A device for simulating hydraulic pressure to test the reliability of an optical microphone, characterized in that, include: Test chamber (1), oil tank (2) and ultrasonic signal generation system; The test box (1) has a test platform (11) for fixing the optical microphone (9) inside. The test box (1) is provided with a through-hole interface. The through-hole interface is provided with a through-hole (13) for introducing the optical microphone signal line (10). The bottom of the box is provided with a transformer oil inlet and a transformer oil outlet. The oil conservator (2) is connected to the test chamber (1) and is used to provide pressure regulation space for the entire device. The oil conservator (2) is equipped with a pneumatic system and a pressure control system. The pneumatic system includes an inlet valve (3), an exhaust valve (4) and an air pump. The inlet valve (3) and the exhaust valve (4) are installed on the oil conservator (2). The inlet valve (3) is connected to the air pump and is used to apply air pressure to the inside of the oil conservator (2). The exhaust valve (4) is used to release pressure inside the oil conservator (2). The pressure control system includes a pressure relief valve (5). The oil conservator (2) is equipped with multiple pressure relief valves (5) with different pressure thresholds. An ultrasonic signal generating system includes a high-voltage sleeve (7) for applying a high-voltage signal and a discharge model (8) for generating an ultrasonic signal. The high-voltage sleeve (7) is disposed on the top of the test chamber (1), and the discharge model (8) is connected to the bottom of the high-voltage sleeve (7). By pressurizing the air pump and controlling the opening and closing of different pressure relief valves (5), the oil pressure environment at different depths inside the transformer can be simulated to test the performance parameters of the optical microphone (9) under different oil pressures.

2. The apparatus for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 1, characterized in that: The penetrator (13) includes a housing, an optical fiber transmission assembly, and a quick-install sealing mechanism; The outer shell has an accommodating cavity extending through both ends thereto; The optical fiber transmission assembly includes an optical fiber patch cord (T1) and a potting compound (T41). The optical fiber patch cord (T1) passes through the accommodating cavity, and the potting compound (T41) is located inside the accommodating cavity and pots the optical fiber patch cord (T1) inside the accommodating cavity. The optical microphone signal line (10) is connected to the optical fiber patch cord (T1) of the connector (13). The quick-install sealing mechanism is disposed on the outer casing and is used to detachably fix the outer casing to the transition plate of the oil-immersed transformer and achieve a seal. The quick-install sealing mechanism includes a movable rod, a connecting rod (T11), and at least two openable spring pieces (T7). The movable rod is movably disposed on the outer casing along the axial direction of the outer casing. The spring pieces (T7) are linked to the movable rod through the connecting rod (T11). When the movable rod is pushed inward toward the transformer, the spring pieces (T7) are closed to allow the penetrator to pass through the transition plate (T6). When the movable rod is pulled outward toward the transformer, the movable rod moves in the direction of the transformer's outward, and the connecting rod (T11) drives the spring pieces (T7) to open and press tightly against the inner wall of the transformer to achieve a compression seal.

3. The apparatus for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 1, characterized in that: The pressure control system also includes a vacuum pump, which is connected to the oil tank (2) and is used to evacuate the inside of the oil tank (2).

4. The apparatus for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 1, characterized in that: The pressure control system also includes a pressure gauge connected to the oil reservoir (2).

5. The apparatus for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 1, characterized in that: The pressure relief valves (5) with different pressure thresholds are 0.02 MPa, 0.1 MPa, 0.2 MPa and 0.4 MPa, respectively, so that the transformer oil pressure environment at depths of 1 meter, 5 meters, 10 meters and 20 meters can be simulated inside the test box (1).

6. The apparatus for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 1, characterized in that: The pressure control system also includes a safety valve (6) disposed on the oil tank (2), and the safety valve (6) is normally open.

7. The apparatus for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 1, characterized in that: The ultrasonic signal generation system also includes a function generator and a power amplifier, wherein the function generator is electrically connected to the discharge model (8) through the power amplifier.

8. The apparatus for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 1, characterized in that: The discharge model (8) is a replaceable structure used to simulate different types of partial discharge defects.

9. A method for simulating hydraulic pressure to test the reliability of an optical microphone, characterized in that, The apparatus based on any one of claims 1-8 comprises the following steps: Step 1: Fix the optical microphone (9) on the test platform (11) and lead its signal line out of the test box (1) through the connector (13). Step 2: Pour transformer oil into the test box (1) until the optical microphone (9) is submerged; Step 3: Control the ultrasonic signal generation system to generate ultrasonic signals, and test and record the initial performance parameters of the optical microphone (9) under normal atmospheric pressure; Step 4: Open the air inlet valve (3) and start the air pump to pressurize the device; Step 5: Open a pressure relief valve (5) with a pressure threshold to stabilize the internal pressure of the device at the pressure threshold corresponding to the pressure relief valve (5); Step 6: Under the pressure formed in step 5, control the ultrasonic signal generating system to generate an ultrasonic signal with the same voltage level as in step 3, and test and record the performance parameters of the optical microphone (9) under the current pressure; Step 7: Open the pressure relief valve (5) with different pressure thresholds, repeat steps 5-6, and obtain the performance parameters of the optical microphone (9) under different pressure values; Step 8: Based on the recorded data, analyze the influence of oil pressure on the performance parameters of the optical microphone (9).

10. The method for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 9, characterized in that: When the pressure control system includes an air pump, it includes the step of simulating the internal vacuum environment when the transformer is draining oil, including: the air pump is connected to the oil tank (2), the air pump is used to extract the air inside the device, and the pressure inside the device is detected in real time by an air pressure detection instrument.

11. The method for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 9, characterized in that: The performance parameters include the sensitivity and minimum sensing amount of the optical microphone (9).

12. The method for simulating hydraulic pressure testing the reliability of an optical microphone as described in claim 9, characterized in that: In step 6, the performance parameters of the optical microphone (9) at different frequencies are tested by changing the frequency of the ultrasonic signal.

13. A method for assessing the fatigue life of an optical microphone, characterized in that, The apparatus based on any one of claims 1-8 comprises the following steps: Step 1: Fix the optical microphone (9) on the test platform (11) and lead its signal line out of the test box (1) through the connector (13). Step 2: Pour transformer oil into the test box (1) until the optical microphone (9) is submerged; Step 3: Control the ultrasonic signal generating system to generate ultrasonic signals; Step 4: Open a pressure relief valve (5) with a pressure threshold, which is the maximum oil pressure value of this oil pressure cycle; Step 5: Open the air intake valve (3) and pressurize the device at a constant rate using the air pump until the internal pressure of the device reaches the maximum oil pressure value. Then, open the pressure relief valve (5) in step 4 to release the pressure and release the internal pressure of the device to normal atmospheric pressure, thus completing one oil pressure cycle. Step 6: Repeat the hydraulic circulation of step 5 a predetermined number of times; Step 7: After each predetermined number of cycles, test and record the performance parameters of the optical microphone (9); Step 8: Plot the performance parameters of the optical microphone (9) as a function of the number of hydraulic cycles to evaluate its fatigue life.

Images