Positive pressure sealing test device and method for oil immersion equipment

Abstract

According to the device and method for testing the positive pressure sealing performance of the oil immersion equipment, positive pressure can be accurately applied to the oil immersion equipment through an external air pump, a pressure adjusting cylinder body, a high-pressure oil way system and a fine valve control and pressure monitoring system, and the sealing performance of the oil immersion equipment is detected. A piston is arranged in the pressure adjusting cylinder body and can move through pressure provided by an air pump to apply pressure to an oil way system, a vacuum pump connector is used for vacuumizing and is matched with an exhaust valve to discharge air in a pipeline and suck out insulating oil, the whole system monitors real-time pressure through two pressure gauges to ensure that test conditions meet requirements, and finally the pressure is adjusted to 0.03 MPa through the air pump. And keeping for 24 hours, and judging the sealing property according to the pressure change and the leakage condition. The device can adapt to transformers and electric reactors of different specifications, the working efficiency is improved, potential safety risks and resource consumption are reduced, meanwhile, the purity of insulating oil of equipment is guaranteed, and the risk of oil mixing and the damping of the equipment are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing test for oil-immersed equipment such as transformers and reactors, and is mainly used to judge whether the sealing of the equipment is normal. In particular, the present invention relates to a positive pressure sealing test device and method for oil-immersed equipment. Background Art

[0002] Oil-immersed transformers and reactors utilize internal oil-type metal bellows conservators, which are structurally incapable of withstanding external forces. Therefore, the Installation and Operation Manual explicitly prohibits these conservators from participating in positive pressure seal tests on oil-immersed equipment. Therefore, prior to positive pressure seal tests on oil-immersed equipment equipped with internal oil-type metal bellows conservators, the valve between the conservator and the main unit must be closed. The test device must then be connected to the main unit's interface. After the test is complete, the valve between the conservator and the main unit must be opened again.

[0003] (1) Conduct a sealing test on the transformer, along with the gas relay and oil conservator, in accordance with Section 4.11 of "GB50148-2010 Specification for Construction and Acceptance of Power Transformers, Oil-Immersed Reactors, and Instrument Transformers for Electrical Installation Engineering," 4.11.3. This test can be performed using an oil column or nitrogen gas, pressurized to 0.03 MPa at the top of the oil tank. For 110kV to 750kV transformers, the sealing test should last 24 hours and ensure no leakage. When required by the product technical documentation, this test should be conducted in accordance with the requirements. Transformers and reactors transported as a whole do not require an overall sealing test.

[0004] (2) According to the requirements of Section 6 - 6.2 Pressure Seal Test - 6.2.4 C of "DL / T264-2022 Guidelines for Field Seal Test of Oil-Immersed Power Transformers (Reactors)" (pressure seal test of corrugated (internal oil) oil conservator transformer): After the vacuum oil filling is completed, close the connecting valve between the oil conservator and the main body. Then, install a process oil conservator on the transformer cover at the same height as the original oil conservator, and then fill the process oil conservator with dry air or nitrogen at a pressure of 30kPa through the breathing port.

[0005] (3) According to the requirements of Part 9 - 9.2 Assembly - 9.2.6 Overall Sealing Test of "DLBT573-2010 Power Transformer Maintenance Guidelines", the transformer should be subjected to sealing test on site after assembly.

[0006] (IV) According to the 17 requirements in Section 5 - AC Power Transformers - 5.1 Oil-Immersed Power Transformers - Table 3 of "Q / CSG1205019-2018 Electric Power Equipment Acceptance and Acceptance Procedures," the entire transformer (including all oil-filled accessories, excluding the bellows conservator) must be able to withstand a static pressure of 30 kPa (0.03 MPa, for standardization throughout) applied to the oil level of the conservator for 24 hours without leakage or damage. The test methods and procedures are in accordance with DL / T 264, "Guidelines for Field Sealing Tests of Oil-Immersed Power Transformers (Reactors)."

[0007] (5) According to the sealing test provisions of Section 6.4-6.4.15 of the "Technical Specifications for 10kV-500kV AC Transformers (2022 Edition)" of the Southern Power Grid: The entire transformer (including all oil-filled accessories, excluding the bellows oil conservator) should be able to withstand a static pressure of 30kPa (converted to 0.03Mpa, unified throughout the text) applied to the oil surface of the oil conservator for 24 hours without leakage or damage.

[0008] The insulating oil in oil-immersed equipment is sensitive to moisture and impurities. If moisture enters the interior of the device during the test, it will cause internal discharge after the insulating oil becomes damp and put into operation, resulting in abnormal chromatographic analysis data and requiring power outage for maintenance. It may even cause the iron core coil to become damp and need to be returned to the factory for drying, which will indefinitely delay time and incur high maintenance costs.

[0009] Most oil-immersed equipment uses internal oil type metal bellows oil conservator. It is impossible to conduct on-site testing by directly pressurizing the oil tank. Instead, it must be tested through an external process oil pillow or other methods. As a result, equipment that fails to be tested during construction is considered to be defective equipment and cannot be put into operation if it fails acceptance. This is very troublesome in the infrastructure field and maintenance operations. Currently, there are two commonly used testing methods in the entire power grid construction process: the "oil column method" (pressure sealing test of internal oil type metal bellows oil conservator) and the "process oil conservator air pressure method" (internal oil type metal bellows oil conservator transformer, i.e. oil-immersed equipment) to carry out testing (pressure sealing test).

[0010] Method 1: The oil column method: This method generates pressure by hoisting the test oil tank. The test tank's suspension or hoisting height is determined by calculation based on parameters such as the oil volume and the positive pressure test pressure. The test tank, filled with insulating oil, is then hoisted by crane to a position roughly aligned with the oil pillow height of the on-site transformer or reactor bushing. The high-voltage pipeline is connected, the valve is opened, and the head pressure is used to push the insulating oil in the test tank into the transformer, achieving the test objective. This method has the following major issues: 1. It requires resources such as a crane, an aerial work vehicle, and operators to maintain the test tank 24 hours a day; 2. There is a risk of mixing the insulating oil in the test tank with the insulating oil in the oil-immersed equipment to be tested; 3. The test tank and high-voltage pipelines are not vacuumed before the test, which may allow moisture to enter the oil-immersed equipment to be tested through the high-voltage pipelines.

[0011] Method 2, the air pressure method, uses a capsule inside a capsule-type process oil conservator to transmit pressure. The lifting height of the capsule-type process oil conservator is determined by calculation based on parameters such as the oil volume and the positive pressure test pressure. The capsule-type process oil conservator, filled with insulating oil, is then hoisted using a crane to a position roughly aligned with the bushing oil pillow of the on-site transformer or reactor. The pressure is then inflated by inflating the capsule inside the conservator, indirectly transmitting the pressure to the insulating oil on the top surface of the oil-immersed equipment. This pressure is maintained for 24 hours until the rated pressure is reached. This test method also has the following major issues: 1. It requires resources such as a crane, an aerial work platform, and operators to maintain the test oil tank 24 hours a day; 2. There is a risk of mixing the insulating oil in the test tank with the insulating oil in the oil-immersed equipment to be tested; 3. The test tank and high-pressure piping are not evacuated before the test, which may allow moisture to enter the oil-immersed equipment to be tested through the high-pressure piping.

[0012] In light of the aforementioned difficulties and challenges, we propose a "positive pressure seal test method and apparatus for oil-immersed equipment." The test insulating oil of this invention is derived from qualified insulating oil in the insulating equipment to be tested, eliminating the risk of oil mixing. Summary of the Invention

[0013] In view of the many defects and deficiencies in the above-mentioned background technology, the oil-immersed transformers and reactors equipped with an oil pillow of an internal oil-type metal bellows oil storage cabinet cannot perform an overall sealing test by applying positive pressure to the oil-immersed equipment body through the oil storage cabinet due to the special structure of the oil storage cabinet and the inability of the metal bellows in the oil pillow to withstand external forces. The inventors have made improvements and innovations to this, and after designing and conducting experiments, they have provided a positive pressure sealing test device and method for oil-immersed equipment. The device and method have a reasonable and compact structure, are easy to operate and use, and can avoid the above-mentioned risks when conducting an overall sealing test on oil-immersed equipment equipped with an internal oil-type metal bellows oil storage cabinet structure, and can complete the test safely, reliably, labor-saving, time-saving, and cost-effectively. This technical problem can be efficiently solved in both the infrastructure field and the production and maintenance field. In order to solve the above-mentioned problems and achieve the above-mentioned purpose of the invention, the present invention is realized by adopting the following design structure and the following technical solutions:

[0014] A positive pressure sealing test device for oil-immersed equipment, directly connected and installed with the oil circuit system of the oil-immersed equipment, comprising:

[0015] The external pressure regulating system includes an external air pump, a pressure regulating cylinder connected to the external air pump, and a piston movable in the pressure regulating cylinder. The system is connected to the oil circuit system of the oil-immersed equipment through the high-pressure oil circuit system, and can provide positive pressure to the oil-immersed equipment body.

[0016] The oil circuit system includes a high-pressure main oil pipe, one end of which is connected to the oil outlet at the bottom of the oil-immersed device and the other end is connected to the inside of the pressure regulating cylinder; and a high-pressure branch oil pipe, one end of which is connected to the oil inlet at the top of the oil-immersed device and the other end is connected to the high-pressure main oil pipe;

[0017] The control valve system includes a main body butterfly valve, which is installed on the end of the high-pressure branch oil pipe near the oil inlet; a main body gate valve, which is installed on the end of the high-pressure main oil pipe near the oil outlet; a first check valve, which is installed on the high-pressure branch oil pipe; a second check valve, which is installed on the tail end of the pressure regulating cylinder, and an external air pump is connected to the pressure regulating cylinder after being connected to the second check valve; a first exhaust valve and vacuum pump interface is installed on the end of the first check valve; a second exhaust valve and vacuum pump interface is installed on the end of the second check valve; the first exhaust valve and vacuum pump interface and the second exhaust valve and vacuum pump interface can each be connected to a vacuum pump pipeline, and the vacuum pump pipeline includes a vacuum suction pump.

[0018] Furthermore, the external air pump can inject air pressure into one side of the piston in the pressure regulating cylinder through the second check valve, pushing the piston to squeeze to the other side to provide pressure, and a second pressure gauge is installed on the pressurized side to detect and display the real-time pressure value in the current pressure regulating cylinder.

[0019] Furthermore, a first pressure gauge is installed at the tail end of the first check valve for detecting and displaying the real-time pressure value of the oil pressure in the current high-pressure branch oil pipe.

[0020] Furthermore, the outer end of the pressure regulating cylinder is connected to the interior of the pressure regulating cylinder through a conversion seat, and the second exhaust valve and vacuum pump interface and the second check valve are installed on the conversion seat. A manual valve is installed at the outer end of the second check valve, and the second check valve is connected to the external air pump by connecting the manual valve.

[0021] Furthermore, a sealing ring is sleeved on the side of the piston.

[0022] Another aspect of the present invention provides a positive pressure seal test method for a positive pressure seal test device for oil-immersed equipment, comprising the following steps:

[0023] Step S1, first check the status of the control valve system to ensure that the main body butterfly valve and the main body gate valve are closed (note: if the oil inlet and oil outlet are equipped with valves, they should also be kept in the same open and closed state as the main body butterfly valve and the main body gate valve); open the first exhaust valve and vacuum pump interface and the second exhaust valve and vacuum pump interface, and connect them to the vacuum pump pipeline respectively; if only one set of vacuum suction pump is used, first connect the second exhaust valve and vacuum pump interface to vacuum the pressure regulating cylinder and reset the piston position; then connect the first exhaust valve and vacuum pump interface to suction and exhaust the oil circuit system.

[0024] Step S2: Start the vacuum pump to evacuate the pressure regulating cylinder and the entire oil system to ensure that all moisture in the high-pressure main oil pipe and the high-pressure branch oil pipe is extracted by the vacuum suction pump;

[0025] Step S3: Close the first exhaust valve and vacuum pump interface and the second exhaust valve and vacuum pump interface, and slowly open the main gate valve at the bottom of the oil-immersed equipment to allow the insulating oil sucked out of the oil-immersed equipment to fill the entire high-voltage main oil pipe and the pressure regulating cylinder;

[0026] Step S4: Slowly open the first exhaust valve and vacuum pump interface until the insulating oil is continuously discharged and then close it, and then close the main gate valve at the bottom of the oil-immersed equipment;

[0027] Step S5: Open the butterfly valve on the top of the oil-immersed device and check whether the piston in the pressure regulating cylinder moves to the left side of the cylinder normally under the push of air pressure by observing the pressure value change on the pressure gauge on the pressure regulating cylinder.

[0028] Step S6: Use an external air pump to inject compressed air into the outside of the piston of the pressure regulating cylinder to push the piston in the cylinder toward the inside of the cylinder. Compare the pressure values ​​of the first pressure gauge and the second pressure gauge in real time. When the pressure value reaches 0.03 MPa as required by the specification, stop pressurizing. Check whether there are any signs of oil leakage on the oil-immersed equipment and the sealing surfaces. After observing that the pressure value of the first pressure gauge of the oil-immersed equipment body is stable, start timing and keep it for 24 hours. Record the time, ambient temperature and humidity, and take photos to record the pressure indication position for later comparison.

[0029] Furthermore, in step S7, after 24 hours of observation, according to the data displayed by the first pressure gauge, compared with the test pressure recorded 24 hours ago, there should be no significant decrease, and all connection parts of the oil-immersed equipment should be checked for leakage. Based on the above inspection results, the test conclusion is given;

[0030] Step S8: After the test is completed, close the butterfly valve on the top of the oil-immersed equipment, check and confirm that the bottom body valve is closed, remove the test device and high-pressure pipeline, clean the work site and oil stains on the equipment surface, remove the test equipment from the work site, and record and confirm one by one.

[0031] Furthermore, the method further comprises the following steps:

[0032] To adjust the piston position within the pressure-regulating cylinder, if the piston needs to be moved outward, the second exhaust valve / vacuum pump interface is opened, and a vacuum line is connected. The vacuum pump then pumps air to displace the piston outward. To move the piston inward, the second exhaust valve / vacuum pump interface is closed, and an external air pump is operated to pressurize air, pushing the piston inward. The term "outward piston displacement" as used herein refers to piston retraction (reset), while "inward piston movement" refers to piston extension (compression).

[0033] Furthermore, the method further comprises the following steps:

[0034] The outer end of the pressure regulating cylinder is connected to the interior of the pressure regulating cylinder via a conversion seat, the conversion seat is mounted with the second exhaust valve and vacuum pump interface and the second check valve, the outer end of the second check valve is mounted with a manual valve, and the second check valve is connected to the external air pump via the manual valve;

[0035] In step S1, when the first exhaust valve and vacuum pump interface and the second exhaust valve and vacuum pump interface are opened, the manual valve is closed;

[0036] In step S3, when the first exhaust valve and vacuum pump interface and the second exhaust valve and vacuum pump interface are closed, the manual valve is closed;

[0037] In step S6, the external air pump injects compressed air into the outside of the piston of the pressure regulating cylinder to push the piston in the cylinder to move toward the inside of the cylinder, and then opens the manual valve; when the pressure value reaches 0.03Mpa required by the specification, the pressurization is stopped and the manual valve is closed.

[0038] The working principle of the present invention is as follows: The present invention provides a positive pressure sealing test device and method specifically for oil-immersed equipment such as transformers and reactors, which aims to use a more convenient, safe and efficient method to conduct positive pressure sealing tests on oil-immersed equipment, so as to ensure the sealing performance of these equipment under high pressure quickly, safely and without interference. The working process of the present invention can be summarized as follows: Preparation stage: First, ensure that all valves are closed, including the lower gate valve of the oil-immersed equipment, the upper butterfly valve, and the connecting valves between the oil pillow and the main body. Next, connect the pressure regulating cylinder to the oil-immersed equipment body through a high-pressure oil pipe, and connect the vacuum suction pump through the second exhaust valve and vacuum pump interface on the right side. After restoring the piston to the initial position, close the manual valve. Vacuuming and inspection: The entire high-pressure pipeline system is vacuumed by a vacuum suction pump to remove moisture and air in the pipeline to ensure sealing. This step includes checking the sealing of all joints and using the piston and seals in the pressure regulating cylinder to maintain the cylinder seal, ensuring that the pressure regulating cylinder and the oil system maintain a vacuum negative pressure state. Oil Filling and Pressure Testing: Open the gate valve at the bottom of the oil-immersed equipment to allow insulating oil to fill the high-pressure pipeline and pressure regulating cylinder. Then, slowly open the vent valve to purge the air from the pipeline until the insulating oil leaks out, then close the valve to ensure there are no leaks. Pressurization and Monitoring: Use a manual air pump to inject compressed air into the right side of the pressure regulating cylinder, pushing the piston to the left. Monitor the pressure using a pressure gauge. When the pressure reaches 0.03 MPa, stop pressurizing and inspect the equipment's sealing surfaces for oil leaks. Maintain this pressure for 24 hours, recording the pressure, time, and environmental conditions to ensure the pressure remains stable and does not drop, thus verifying the reliability of the seal. Completion and Evaluation: Upon completion of the test, close the butterfly valve on top of the equipment, gradually restore the equipment to its normal operating configuration, dismantle the test equipment, and clean the site. Compare the pressure data before and after 24 hours to evaluate the equipment's sealing performance and provide the final test conclusions. This technology, through meticulous procedures and specialized equipment design, enables efficient and accurate testing of the sealing properties of oil-immersed equipment. Its advantage is that it can adapt to transformers and reactors of different specifications, improve work efficiency, reduce potential safety risks and resource consumption, and at the same time ensure the purity of the equipment's insulating oil, avoid oil contamination and equipment moisture. It is a major advancement in the field of power equipment maintenance and testing.

[0039] The beneficial effects of the present invention compared with the prior art are:

[0040] (1) Excellent applicability and economy: By optimizing the connection and coordination between the pressure regulating cylinder, manual air pump and oil system, the device can adapt to the sealing test requirements of oil-immersed equipment such as transformers and high-voltage reactors of different capacities, without the need for traditional tedious and high-cost operations such as high-altitude operations and crane intervention. This flexibility improves work efficiency, has a scientific and reasonable structure, is easy to operate, convenient and effective, and saves operating costs and time costs.

[0041] (2) Maintaining the quality of oil products: By optimizing the vacuum system and ensuring the dryness and cleanliness of the pipelines, this technical solution effectively prevents the oil products from being contaminated by the outside world during the test process. It also avoids the situation where the test oil tank and high-pressure pipelines are not vacuumed before the test, and moisture may enter the oil-immersed equipment to be tested through the high-pressure pipelines, etc.; thus, the safety of the oil products during the test process is ensured.

[0042] (3) Avoiding the risk of oil mixing: By using the same batch of insulating oil as that in the oil-immersed equipment to be tested, it is ensured that no new oil will be introduced during the test, avoiding the risk of equipment damage and performance degradation caused by oil mixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0044] Figure 1 The present invention is a schematic diagram of the structure of a positive pressure sealing test device for oil-immersed equipment.

[0045] in,

[0046] 1—external air pump, 11—conversion seat, 12—sealing ring;

[0047] 2—pressure regulating cylinder, 21—piston,

[0048] 31—high-pressure main oil pipe, 32—high-pressure branch oil pipe,

[0049] 41 - body butterfly valve, 42 - body gate valve, 43 - first check valve, 44 - second check valve, 45 - first exhaust valve and vacuum pump interface, 46 - second exhaust valve and vacuum pump interface, 47 - manual valve,

[0050] 5—Oil immersed equipment, 51—Oil inlet, 52—Oil outlet,

[0051] 61—first pressure gauge, 62—second pressure gauge. DETAILED DESCRIPTION

[0052] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the technical solutions of the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other unless there is a conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0053] Example 1: A positive pressure seal test device for oil-immersed equipment, directly connected to the oil system of the oil-immersed equipment 5, mainly includes the following equipment:

[0054] The external air pump 1 is a pressure source and is responsible for generating gas pressure. A manual air pump is usually used to provide internal pressure to the pressure regulating cylinder 2 by injecting air into the pressure regulating cylinder 2 .

[0055] Pressure-regulating cylinder 2: Contains piston 21, which receives pressure from the air pump and converts it into pressure for the oil system. Piston 21, located within pressure-regulating cylinder 2, moves inward when subjected to gas pressure from the air pump, exerting pressure on the liquid oil within the cylinder. Conversely, when the outer end of piston 21 is under vacuum, it attracts and moves the piston outward, resetting or adjusting its position.

[0056] High-pressure oil circuit system: connected to the oil inlet and outlet interfaces of the oil-immersed equipment 5, the high-pressure oil circuit can be vacuumed, and can also suck out the insulating oil in the oil-immersed equipment 5 to fill the pipeline after being connected to the oil-immersed equipment 5. When the pressure regulating cylinder 2 provides positive pressure, it can also form a positive pressure to the inside of the oil-immersed equipment 5 through the oil circuit system.

[0057] Specifically, the connection structure of the high-pressure oil system is as follows:

[0058] High-pressure main oil pipe 31: Starting from the oil outlet 52 at the bottom of the oil-immersed device 5, it is connected to the inside of the pressure regulating cylinder 2 and is used to transport oil.

[0059] High-pressure branch oil pipe 32: One end is connected to the oil inlet 51 on the top of the oil-immersed device 5, and the other end is connected to the high-pressure main oil pipe 31, forming a loop to ensure that the oil can flow from the high-pressure main oil pipe 31 to the high-pressure branch oil pipe 32 and then to the oil-immersed device 5, forming a circulation flow;

[0060] The control valve system includes:

[0061] The main body butterfly valve 41 is installed on one end of the high-pressure branch oil pipe 32, close to the oil inlet 51 of the oil-immersed device 5, and is used to control the opening or closing of the oil flow;

[0062] Main gate valve 42: located on the high-pressure main oil pipe 31, close to the oil outlet 52 of the oil-immersed equipment 5, and is also used to control the opening and closing of the oil system;

[0063] First check valve 43: installed on the high-pressure branch oil pipe 32 to prevent the oil from flowing in the reverse direction toward the pressure regulating cylinder 2;

[0064] The second check valve 44 is installed at the tail end of the pressure regulating cylinder 2 to prevent the air pressure from leaking out in the opposite direction, but the air pump can supply air to the cylinder through this valve.

[0065] The first exhaust valve and vacuum pump interface 45 is installed at the end of the first check valve 43, and can be connected to a vacuum pump to perform a vacuum operation to evacuate the air in the high-pressure branch oil pipe 32, and realize the on-off connection between the oil circuit system and the vacuum pump through the valve body.

[0066] The second exhaust valve and vacuum pump interface 46 is installed on the conversion seat 11 between the second check valve 44 and the pressure regulating cylinder 2, and can be directly connected to the pressure regulating cylinder 2. The function is the same as above. After opening, it can be used to evacuate the pressure regulating cylinder 2, and to adjust the pressure in the pressure regulating cylinder 2 and the displacement control of the piston 21.

[0067] The pressure monitoring and control system includes:

[0068] The second pressure gauge 62 is installed on the pressure side of the pressure regulating cylinder 2 and can display the real-time pressure in the cylinder.

[0069] The first pressure gauge 61 is installed at the tail end of the first check valve 43 or on the high-pressure branch oil pipe 32 , and can display the real-time oil pressure in the high-pressure branch oil pipe 32 .

[0070] Conversion seat 11: Installed on the outer end of the pressure regulating cylinder 2, it has a channel inside and is integrated with the second exhaust valve and vacuum pump interface 46, the second check valve 44, and the manual valve. The manual valve 47 is installed on the outer end of the second check valve 44 and is used to control the air flow between the air pump and the pressure regulating cylinder 2. When it is necessary to vacuum through the second exhaust valve and vacuum pump, the manual valve 47 needs to be closed; when the second exhaust valve and vacuum pump is closed, the manual valve 47 needs to be opened, and the external air pump 1 can be directly injected into the pressure regulating cylinder through the conversion seat 11.

[0071] Sealing ring 12 on the side of piston 21 ensures that oil and gas inside the pressure-regulating cylinder 2 do not leak as piston 21 moves, maintaining a good seal. Through sophisticated valve control and pressure regulation, the entire system establishes and maintains a stable positive pressure environment within the oil-immersed device 5 to test its sealing performance.

[0072] Example 2: A positive pressure sealing test device for oil-immersed equipment 5 based on Example 1, in actual use:

[0073] Due to the special structure of the oil-immersed equipment 5 of the internal oil type metal bellows oil conservator, the metal bellows cannot withstand external force. Therefore, it is not possible to apply pressure to the body of the oil-immersed equipment 5 through the metal bellows to perform an overall sealing test.

[0074] The pressure regulating cylinder 2 is made of steel casting type and its joints are made of φ50 pipe diameter. The gate valve 42 and butterfly valve of the oil immersed equipment 5 are made of φ50 pipe diameter. The high pressure oil pipe is made of high pressure oil pipe with steel wire. The vacuum suction pump is made of low power type. The exhaust valve and vacuum pipe interface are made of φ50 pipe diameter.

[0075] After placing the positive pressure sealing test device at the test site, connect the pressure regulating cylinder 2 to the manual air pump and tighten the joints. After connecting the pressure regulating cylinder 2 to the high-pressure oil pipe, the main gate valve 42, the main butterfly valve 41, the check valve, the exhaust valve and vacuum pump interface, the vacuum tube, and the pressure gauge, check the tightening joints and check the data of the first pressure gauge 61 and the second pressure gauge 62;

[0076] Check that the upper butterfly valve and the lower gate valve 42 of the oil-immersed equipment 5 are in the closed state;

[0077] Open the exhaust valve and vacuum pump interface, start the vacuum pump to evacuate the connected pipeline to meet the requirements, and then close the exhaust valve and vacuum pump interface.

[0078] The oil-immersed device 5, the main butterfly valve, and the main gate valve 42 are all closed. Before use, connect the vacuum pump line to the exhaust valve / vacuum line interface and evacuate the pressure regulating cylinder 2 and the entire pipeline. Then, slowly open the main gate valve 42 at the bottom of the oil-immersed device 5 to allow insulating oil to fill the entire high-pressure oil pipeline and the pressure regulating cylinder 2. The oil pressure then pushes the piston 21 in the pressure regulating cylinder 2 to the right.

[0079] Open the exhaust valve and vacuum pipe interface to discharge the gas in the pipeline. After the pressure in the pipeline is balanced and the insulating oil is continuously discharged, first open the exhaust valve and vacuum pipe interface, and then close the main gate valve 42 at the bottom of the oil-immersed equipment 5. Then open the main butterfly valve at the top of the oil-immersed equipment 5.

[0080] Inject air into the pressure regulating cylinder 2 through the manual air pump 1 of the pressure regulating cylinder 2 to change the position of the piston 21 to achieve the purpose of regulating the pressure. When the pressure value reaches 0.03Mpa, check whether there is any leakage in the high-pressure pipe and each connection part. After confirming that there is no leakage, record the data of the second pressure gauge 62 and the first pressure gauge 61 and keep it for 24 hours.

[0081] After 24 hours of observation, according to the data displayed by the first pressure gauge 61, compared with the test pressure recorded 24 hours ago, there is no obvious decrease, so it is judged that the test result is qualified.

[0082] After the test is completed, close the bottom and top valves of the oil-immersed equipment 5, open the valve between the oil storage cabinet and the body, remove the high-pressure pipeline, clean the work site and the oil stains on the equipment surface, remove the test equipment from the work site, and record and confirm each one;

[0083] In this embodiment:

[0084] 1. All high-pressure pipelines between the pressure regulating cylinder 2 and the high-pressure oil pipe, the main gate valve 42, the main butterfly valve, the check valve, the exhaust valve and vacuum pump interface, the vacuum tube, and the second and first pressure gauges 61 must be dried and cleaned before use;

[0085] 2. Check the connection status of each joint at any time during the test;

[0086] 3. During the test, it is strictly forbidden to allow the oil-immersed equipment 5 to get wet or bring air into the body of the device;

[0087] This embodiment uses this device and test method when the oil-immersed equipment 5 is newly installed or encountered during production and maintenance operations when the oil conservator is configured as an internal oil type metal bellows oil conservator.

[0088] In this embodiment, various parameters need to be determined according to the different capacities of the oil-immersed equipment 5 being tested. At the same time, the diameters of the main gate valve 42 and the main gate valve 42 joints need to be confirmed in advance. If the manufacturer's matching pipe diameter does not match the test equipment, matching joint components need to be processed in advance.

[0089] When carrying out the operation in this embodiment, it should be ensured that the humidity of the working environment is ≤80%, there is no visible dust around the working environment, and the weather should be clear.

[0090] The test process of this embodiment is as follows:

[0091] Step (1) Check and restore the position of the piston 21. Connect a vacuum suction pump to the valve interface on the right side of the cylinder head, turn on the vacuum suction pump to restore the piston 21 to the right side of the cylinder body, and close the valve.

[0092] Step (2) Before starting the test operation, confirm that the gate valve at the bottom of the body, the butterfly valve at the top of the body, and the valve between the internal oil type metal bellows oil storage cabinet and the body are in the closed state, check that the butterfly valve between the body and the oil pillow is in the closed state, and connect the high-pressure oil pipe between the pressure regulating cylinder 2 and the body oil tank;

[0093] Step (3) First check the status of each valve in the device. Then connect the vacuum pump pipeline to the "exhaust valve and vacuum pipe interface" and vacuum the "pressure regulating cylinder 2" and the entire high-pressure pipeline to ensure that all moisture in the pipeline is extracted by the vacuum pump.

[0094] Step (4) Close the exhaust valve on the "exhaust valve and vacuum tube interface" and then slowly open the "body gate valve 42" at the bottom of the oil-immersed equipment 5 to allow the insulating oil to fill the entire high-pressure pipeline and the left side of the piston 21 in the "pressure regulating cylinder 2", and check whether the entire high-pressure pipeline has any leakage.

[0095] Step (5) Slowly open the exhaust valve on the "exhaust valve and vacuum tube interface" to exhaust the gas in the pipeline and continuously exhaust the insulating oil, then close the exhaust valve first, then close the main gate valve 42 at the bottom of the oil-immersed equipment 5, and check whether there is any oil leakage at each joint;

[0096] Step (6) Open the butterfly valve on the top of the oil-immersed equipment 5.

[0097] Step (7) Check whether the piston 21 in the "pressure regulating cylinder 2" moves to the left side of the cylinder under the push of air pressure. Observe the pressure value of the pressure gauge on the pressure regulating cylinder 2.

[0098] Step (8) A manual air pump is used to inject compressed air into the right side of the piston 21 of the pressure regulating cylinder 2 to push the piston 21 in the cylinder to move toward the left side of the cylinder. The pressure values ​​of the two pressure gauges are compared in real time. When the pressure value reaches 0.03 MPa as required by the specification, the pressurization is stopped. The oil-immersed equipment 5 and each sealing surface are checked for signs of oil leakage. After the pressure value of the first pressure gauge 61 of the oil-immersed equipment 5 body is observed to be stable, the timing is started and maintained for 24 hours. The time, ambient temperature and humidity are recorded, and the pressure indication position is photographed for later comparison.

[0099] Step (9) Observe for 24 hours and compare the test pressure recorded 24 hours ago with the data displayed by the first pressure gauge 61. There should be no obvious decrease. Check that there is no leakage at all connection parts of the oil-immersed equipment 5. Based on the above inspection results, give the test conclusion.

[0100] After the test in step (10) is completed, close the main body butterfly valve on the top of the oil-immersed equipment 5, open the valve between the oil-immersed equipment 5 to be tested and the main body, remove the test device and high-pressure pipeline, clean the work site and oil stains on the equipment surface, evacuate the test equipment from the work site, and record and confirm them one by one.

[0101] Finally, it should be noted that the above has clearly and completely described the concept, specific structure and technical effects of the present invention in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, all the connections and connection relationships mentioned in the text do not refer to the direct connection of components, but refer to the fact that a better connection structure can be formed by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the invention can be combined interactively without conflicting with each other.

Claims

1. A positive pressure sealing test device for oil immersed equipment, directly connected to the oil system of the oil immersed equipment (5), characterized in that include: An external pressure regulating system comprises an external air pump (1), a pressure regulating cylinder (2) connected to the external air pump (1), and a piston (21) movable in the pressure regulating cylinder (2), and is connected to an oil circuit system of an oil-immersed device (5) through a high-pressure oil circuit system, and is capable of providing positive pressure to the body of the oil-immersed device (5); The oil circuit system includes a high-pressure main oil pipe (31), one end of which is connected to the oil outlet (52) at the bottom of the oil-immersed device (5) and the other end is connected to the inside of the pressure regulating cylinder (2); and a high-pressure branch oil pipe (32), one end of which is connected to the oil inlet (51) at the top of the oil-immersed device (5) and the other end is connected to the high-pressure main oil pipe (31); The control valve system comprises a main body butterfly valve (41) installed on one end of the high-pressure branch oil pipe (32) near the oil inlet (51); a main body gate valve (42) installed on one end of the high-pressure main oil pipe (31) near the oil outlet (52); a first check valve (43) installed on the high-pressure branch oil pipe (32); a second check valve (44) installed on the tail end of the pressure regulating cylinder (2); an external air pump (1) connected to the pressure regulating cylinder (2) after being connected to the second check valve (44); a first exhaust valve and vacuum pump interface (45) is installed on the end of the first check valve (43); a second exhaust valve and vacuum pump interface (46) is installed on the end of the second check valve (44); the first exhaust valve and vacuum pump interface (45) and the second exhaust valve and vacuum pump interface (46) can each be connected to a vacuum pump pipeline, and the vacuum pump pipeline includes a vacuum suction pump.

2. The positive pressure sealing test device for oil immersed equipment according to claim 1, characterized in that: The external air pump (1) can inject air pressure into one side of the piston (21) in the pressure regulating cylinder (2) through the second check valve (44), pushing the piston (21) to squeeze the other side to provide pressure, and a second pressure gauge (62) is installed on the pressure-receiving side for detecting and displaying the real-time pressure value in the current pressure regulating cylinder (2).

3. The positive pressure sealing test device for oil immersed equipment according to claim 2, characterized in that: A first pressure gauge (61) is installed at the tail end of the first check valve (43) for detecting and displaying the real-time pressure value of the oil pressure in the current high-pressure branch oil pipe (32).

4. The positive pressure sealing test device for oil immersed equipment according to claim 3, characterized in that: The outer end of the pressure regulating cylinder (2) is connected to the interior of the pressure regulating cylinder (2) via a conversion seat (11); the second exhaust valve and vacuum pump interface (46) and the second check valve (44) are installed on the conversion seat (11); a manual valve (47) is installed at the outer end of the second check valve (44); and the second check valve (44) is connected to the external air pump (1) via the manual valve (47).

5. The positive pressure sealing test device for oil immersed equipment according to claim 1, characterized in that: A sealing ring (12) is sleeved on the side of the piston (21).

6. A positive pressure seal test method for oil-immersed equipment according to any one of claims 1 to 5, characterized in that The following steps are involved: Step S1: First check the status of the control valve system to ensure that the main body butterfly valve (41) and the main body gate valve (42) are closed; open the first exhaust valve and vacuum pump interface (45) and the second exhaust valve and vacuum pump interface (46), and connect them to the vacuum pump pipeline respectively; Step S2, start the vacuum pump to evacuate the pressure regulating cylinder (2) and the entire oil system, ensuring that all moisture in the high-pressure main oil pipe (31) and the high-pressure branch oil pipe (32) is extracted by the vacuum suction pump; Step S3: close the first exhaust valve and vacuum pump interface (45) and the second exhaust valve and vacuum pump interface (46), and slowly open the main gate valve (42) at the bottom of the oil-immersed device (5) to allow the insulating oil sucked out of the oil-immersed device (5) to fill the entire high-pressure main oil pipe (31) and the pressure regulating cylinder (2); Step S4, slowly open the first exhaust valve and vacuum pump interface (45) until the insulating oil is continuously discharged and then close it, and then close the main gate valve (42) at the bottom of the oil-immersed equipment (5); Step S5, opening the butterfly valve (41) on the top of the oil-immersed device (5), and detecting whether the piston (21) in the pressure regulating cylinder (2) moves to the left side of the cylinder under the push of air pressure normally by observing the pressure value change of the pressure gauge on the pressure regulating cylinder (2); Step S6, the external air pump (1) injects compressed air into the outside of the piston (21) of the pressure regulating cylinder (2) to push the piston (21) in the cylinder to move toward the inside of the cylinder, and compares the pressure values ​​of the first pressure gauge (61) and the second pressure gauge (62) in real time. When the pressure value reaches 0.03 MPa required by the specification, the pressure is stopped, and the oil-immersed equipment (5) and each sealing surface are checked for signs of oil leakage. After the pressure value of the first pressure gauge (61) of the oil-immersed equipment (5) body is observed to be stable, the timing is started and maintained for 24 hours, and the time, ambient temperature and humidity are recorded, and the pressure indication position is photographed for later comparison.

7. The positive pressure sealing test method according to claim 6, characterized in that The following steps are also included: Step S7: After 24 hours of observation, the data displayed by the first pressure gauge (61) is compared with the test pressure recorded 24 hours ago. There should be no significant decrease. All connection parts of the oil-immersed equipment (5) should be checked for leakage. Based on the above inspection results, the test conclusion is given; Step S8: After the test is completed, close the butterfly valve on the top of the oil-immersed equipment (5), check and confirm that the bottom body valve is closed, remove the test device and high-pressure pipeline, clean the work site and the oil stains on the equipment surface, remove the test equipment from the work site, and record and confirm them one by one.

8. The positive pressure sealing test method according to claim 6, characterized in that The following steps are also included: When adjusting the position of the piston (21) in the pressure regulating cylinder (2), if the piston (21) needs to be moved outward, the second exhaust valve and vacuum pump interface (46) is opened, and the vacuum pipe is connected, and the piston (21) is moved toward the outer end by suction through the vacuum suction pump; when the piston (21) needs to be moved inward, the second exhaust valve and vacuum pump interface (46) is closed, and the external air pump (1) is operated to pressurize air to push the piston (21) toward the inner section.

9. The positive pressure sealing test method according to claim 6, characterized in that The following steps are also included: The outer end of the pressure regulating cylinder (2) is connected to the interior of the pressure regulating cylinder (2) via a conversion seat (11); the second exhaust valve and vacuum pump interface (46) and the second check valve (44) are installed on the conversion seat (11); a manual valve (47) is installed on the outer end of the second check valve (44); the second check valve (44) is connected to the external air pump (1) via the manual valve (47); In step S1, when the first exhaust valve and vacuum pump interface (45) and the second exhaust valve and vacuum pump interface (46) are opened, the manual valve (47) is closed; In step S3, when the first exhaust valve and vacuum pump interface (45) and the second exhaust valve and vacuum pump interface (46) are closed, the manual valve (47) is closed; In step S6, the external air pump (1) injects compressed air into the outside of the piston (21) of the pressure regulating cylinder (2) to push the piston (21) in the cylinder to move toward the inside of the cylinder, and then opens the manual valve (47); when the pressure value reaches 0.03 MPa required by the specification, the pressure is stopped and the manual valve (47) is closed.

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