Positive pressure sealing test device for oil immersion equipment

Abstract

The utility model provides a device for testing the positive pressure sealing performance of oil immersion equipment, which can accurately apply positive pressure to the oil immersion equipment and detect the sealing performance of the oil immersion equipment through an external air pump, a pressure adjusting cylinder body, a high-pressure oil path system and a fine valve control and pressure monitoring system. 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 utility model relates to the technical field of sealing test of oil-immersed equipment such as transformers and reactors, and is mainly used to judge whether the sealing of equipment is normal, in particular to a positive pressure sealing test device for oil-immersed equipment. Background Art

[0002] For oil-immersed transformers and reactors, the oil pillow adopts the special structure of the internal oil metal bellows oil conservator, which cannot withstand external forces. Therefore, the "Installation and Operation Manual" clearly requires: the internal oil metal bellows oil conservator is prohibited from participating in the positive pressure sealing test of oil-immersed equipment. Therefore, at present, before the positive pressure sealing test of oil-immersed equipment equipped with the internal oil metal bellows oil conservator, the valve between the oil conservator and the main body must be closed first, and then the test device must be connected to the interface of the main body of the oil-immersed equipment to be tested. After the test work is carried out, the valve between the oil conservator and the main body must be opened.

[0003] (I) According to the requirements of Part 4 - 4.11 Oil filling, overall sealing inspection and static storage - 4.11..3 of "GB50148-2010 Electrical Installation Engineering Power Transformer, Oil-immersed Reactor, Transformer Construction and Acceptance Specifications", the transformer together with the gas relay and oil storage cabinet shall be tested for sealing. Oil column or nitrogen can be used to pressurize the top of the oil tank to 0.03MPa. The sealing test duration of 110kV~750kV transformers should be 24h, and there should be no leakage. When there are requirements in the product technical documents, it should be carried out in accordance with the requirements. Transformers and reactors transported as a whole do not need to undergo an overall sealing test.

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

[0005] (III) 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 Part 5 of the "Q / CSG1205019-2018 Electric Power Equipment Handover and Acceptance Procedure" - AC Power Transformer - 5.1 Oil-immersed Power Transformer - Table 3 Oil-immersed Power Transformer Handover and Acceptance Items, Requirements - 17 requirements, the entire transformer (including all oil-filled accessories, except 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, and there should be no leakage or damage. The test methods and procedures are in accordance with the provisions of DL / T 264 "Guidelines for Field Sealing Test of Oil-immersed Power Transformers (Reactors)".

[0007] (V) According to the sealing test provisions of Part 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 the oil-immersed equipment is sensitive to moisture and impurities. If moisture enters the interior of the device during the test, the insulating oil will become damp and discharge internally after it is put into operation, resulting in abnormal chromatographic analysis data and the need for power outage for maintenance. The iron core coil may even become damp and need to be returned to the factory for drying, which will indefinitely delay time and incur high maintenance costs.

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

[0010] Method 1: Oil column method: Use the lift of the test oil tank to generate pressure. According to the parameters such as oil volume and positive pressure test pressure, the hanging or lifting height of the test oil tank is determined by calculation. The test oil tank filled with insulating oil is lifted by a crane to a position basically consistent with the height of the oil pillow of the transformer or reactor bushing on site. The high-pressure pipeline is connected and the valve is opened. The insulating oil in the test oil tank is pushed into the transformer by the lift pressure to achieve the test purpose. This method has the following main problems: 1. It is necessary to invest resources such as cranes, aerial work vehicles and operators to cooperate in hanging the test oil tank for 24 hours; 2. There is a risk of mixing the insulating oil in the test oil tank with the insulating oil in the oil-immersed equipment to be tested; 3. The test oil tank and high-pressure pipeline are not vacuumed before the test, and moisture may enter the oil-immersed equipment to be tested along with the high-pressure pipeline.

[0011] Method 2: Air pressure method: Use the capsule in the capsule-type process oil storage cabinet to transfer pressure. According to the parameters such as oil volume and positive pressure test pressure, the lifting height of the capsule-type process oil storage cabinet is determined by calculation. The capsule-type process oil storage cabinet filled with insulating oil is lifted by a crane to a position basically consistent with the height of the on-site transformer or reactor bushing oil pillow. The capsule in the oil storage cabinet is inflated and pressurized, and the pressure is indirectly transferred to the insulating oil on the top surface of the oil-immersed equipment through the capsule in the process oil storage cabinet, and the rated pressure is maintained for another 24 hours. This test method also has the following major problems: 1. It is necessary to invest resources such as cranes, aerial work vehicles and operators to cooperate in hanging the test oil tank for 24 hours; 2. There is a risk of mixing the insulating oil in the test oil tank with the insulating oil in the oil-immersed equipment to be tested; 3. The test oil tank and high-pressure pipeline were not vacuumed before the test, and moisture may enter the oil-immersed equipment to be tested along with the high-pressure pipeline.

[0012] In view of the above difficulties and pain points, a "positive pressure sealing test method and device for oil-immersed equipment" is proposed. The test insulating oil of the utility model is derived from the qualified insulating oil in the insulating equipment to be tested, that is, there is no risk of oil mixing. Utility Model Content

[0013] In view of the many defects and shortcomings existing 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 body of the oil-immersed equipment 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 for oil-immersed equipment, which has a reasonable and compact structure, is easy to operate and use, and can avoid the above-mentioned risks when conducting an overall sealing test on the 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-saving, and can efficiently solve this technical problem 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 utility model, the present utility model is realized by adopting the following design structure and the following technical solution:

[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, which is connected to the oil circuit system of the oil-immersed device through the high-pressure oil circuit system and can provide positive pressure to the oil-immersed device 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 also includes 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 installed on one end of the high-pressure branch oil pipe close to the oil inlet; a main body gate valve installed on one end of the high-pressure main oil pipe close to the oil outlet; a first check valve installed on the high-pressure branch oil pipe; a second check valve 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; when the second exhaust valve and vacuum pump interface is connected to the vacuum pipeline, the vacuum suction piston can be reset;

[0018] When the first exhaust valve and vacuum pump interface is connected to the vacuum pipeline, it is used to vacuum the high-pressure main oil pipe, the high-pressure branch oil pipe and the pressure regulating cylinder.

[0019] 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.

[0020] 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.

[0021] 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 on the outer end of the second check valve, and the second check valve is connected to an external air pump by connecting the manual valve.

[0022] Furthermore, a sealing ring is sleeved on the side of the piston.

[0023] The actual use includes the following steps:

[0024] 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.

[0025] Step S2, start the vacuum pump to evacuate the pressure regulating cylinder and the entire oil system, and 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;

[0026] Step S3, close the first exhaust valve and vacuum pump interface and the second exhaust valve and vacuum pump interface, slowly open the main gate valve at the bottom of the oil-immersed equipment, so that the insulating oil sucked out of the oil-immersed equipment fills the entire high-voltage main oil pipe and the pressure regulating cylinder;

[0027] Step S4, slowly open the first exhaust valve and vacuum pump interface until the insulating oil is continuously discharged and then closed, and then close the main gate valve at the bottom of the oil-immersed equipment;

[0028] Step S5, opening the main body butterfly valve on the top of the oil-immersed equipment, and checking whether the piston in the pressure regulating cylinder moves to the left side of the cylinder body under the push of air pressure normally by observing the change of the pressure value of the pressure gauge on the pressure regulating cylinder body;

[0029] Step S6, an 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 compares the pressure values ​​of the first pressure gauge and the second pressure gauge in real time. When the pressure value reaches 0.03Mpa as required by the specification, stop pressurizing, check whether there are signs of oil leakage on the oil-immersed equipment and each sealing surface, observe the pressure value of the first pressure gauge of the oil-immersed equipment body to be stable, start timing and keep it for 24 hours, and record the time, ambient temperature and humidity, take a photo to keep the pressure indication position, etc. for later comparison.

[0030] Further, 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 obvious decrease, and all the connection parts of the oil-immersed equipment should be checked for leakage, and the test conclusion is given based on the above inspection results;

[0031] Step S8: After the test is completed, close the main body butterfly valve on the top of the oil-immersed equipment, check and confirm that the main body valve at the bottom is closed, 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.

[0032] When adjusting the piston position in the pressure regulating cylinder, if the piston needs to move outward, open the second exhaust valve and vacuum pump interface, connect the vacuum tube, and use the vacuum suction pump to suck the piston to move it to the outer end; when the piston needs to move inward, close the second exhaust valve and vacuum pump interface, operate the external air pump to pressurize air, and push the piston to move inward. The piston displacement outward in the utility model refers to the piston retracting (resetting), and the piston moving inward refers to the piston extending (compressing).

[0033] The outer end of the pressure regulating cylinder is connected to the inside of the pressure regulating cylinder through a conversion seat, the second exhaust valve and vacuum pump interface and the second check valve are installed on the conversion seat, a manual valve is installed on the outer end of the second check valve, and the second check valve is connected to the external air pump through the manual valve;

[0034] 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;

[0035] 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;

[0036] 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 pressure is stopped and the manual valve is closed.

[0037] The working principle of the utility model is: the utility model provides a positive pressure sealing test device and method specially used for oil-immersed equipment such as transformers and reactors, aiming to use a more convenient, safe and efficient positive pressure sealing test for oil-immersed equipment to ensure the sealing performance of these equipment under high pressure quickly, safely and without interference. The workflow of the utility model 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 body. Then, the pressure regulating cylinder body is connected to the oil-immersed equipment body through a high-pressure oil pipe, and the vacuum suction pump is connected through the second exhaust valve and vacuum pump interface on the right side, and the manual valve is closed after the piston is restored to the initial position. 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 seal in the pressure regulating cylinder body to maintain the cylinder body seal, ensuring that the pressure regulating cylinder body and the oil system maintain a vacuum negative pressure state. Oil filling and pressure test: Open the gate valve at the bottom of the oil-immersed equipment to fill the high-pressure pipeline and pressure regulating cylinder with insulating oil, then slowly open the exhaust valve to remove the gas in the pipeline until the insulating oil leaks out and then close it to ensure no leakage. Pressurization and monitoring: The manual air pump injects compressed air into the right side of the pressure regulating cylinder, pushes the piston to the left, and monitors the pressure value through the pressure gauge. When the pressure reaches 0.03Mpa, stop pressurizing and check whether there is oil leakage on the sealing surface of the equipment. Maintain this pressure for 24 hours, record the pressure, time and environmental conditions, ensure that the pressure is stable and does not drop, and verify the reliability of the seal. End and evaluation: After the test is completed, close the butterfly valve on the top of the equipment, gradually return to the normal working configuration, dismantle the test device, and clean the site. By comparing the pressure data before and after 24 hours, evaluate the sealing performance of the equipment and give the final test conclusion. This technology achieves efficient and accurate testing of the sealing of oil-immersed equipment through sophisticated operating steps and the design of special 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.

[0038] Compared with the prior art, the utility model has the following beneficial effects:

[0039] (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 cumbersome 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.

[0040] (2) Maintaining oil quality: By optimizing the vacuum system and ensuring the dryness and cleanliness of the pipelines, this technical solution effectively prevents the oil 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 ensuring the safety of the oil during the test process.

[0041] (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, thus avoiding the risk of equipment damage and performance degradation caused by oil mixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The specific implementation of the utility model is further described in detail below with reference to the accompanying drawings, wherein:

[0043] Figure 1 The utility model is a schematic diagram of the structure of a positive pressure sealing test device for oil immersed equipment.

[0044] in,

[0045] 1—external air pump, 11—conversion seat, 12—sealing ring;

[0046] 2—pressure regulating cylinder, 21—piston,

[0047] 31—high-pressure main oil pipe, 32—high-pressure branch oil pipe,

[0048] 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,

[0049] 5—Oil immersed equipment, 51—Oil inlet, 52—Oil outlet,

[0050] 61—first pressure gauge, 62—second pressure gauge. DETAILED DESCRIPTION

[0051] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0052] Embodiment 1: A positive pressure sealing test device for oil immersed equipment, directly connected and installed with the oil circuit system of the oil immersed equipment 5, mainly comprising the following equipment:

[0053] 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 .

[0054] 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 is located in pressure regulating cylinder 2. When subjected to gas pressure generated by the air pump, piston 21 moves toward the inner end, thereby exerting pressure on the liquid oil in the cylinder; on the contrary, when the outer end of piston 21 is in a vacuum negative pressure state, it can adsorb piston 21 to move toward the outer end, thereby resetting or adjusting the position of piston 21.

[0055] High-pressure oil circuit system: connected to the oil circuit inlet and outlet interfaces of the oil-immersed equipment 5, the high-pressure oil circuit can be evacuated, 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, and can also continuously provide positive pressure to the inside of the oil-immersed equipment 5 through the oil circuit system when the pressure regulating cylinder 2 provides positive pressure.

[0056] Specifically, the connection structure of the high-pressure oil circuit system is as follows:

[0057] 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.

[0058] 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 to form a loop, ensuring that the oil can be connected from the high-pressure main oil pipe 31 to the high-pressure branch oil pipe 32 to the oil-immersed device 5, forming a circulation flow;

[0059] The control valve system includes:

[0060] 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;

[0061] The main gate valve 42 is 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;

[0062] 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;

[0063] 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 reverse direction, but the air pump can supply air to the cylinder through this valve.

[0064] 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 for vacuum operation to evacuate the air in the high-pressure branch oil pipe 32, and the on-off connection between the oil system and the vacuum pump is realized through the valve body.

[0065] 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 being opened, 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.

[0066] The pressure monitoring and control system includes:

[0067] 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.

[0068] 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 .

[0069] Conversion seat 11: Installed on the outer side 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 side of the second check valve 44 to control the air flow between the air pump and the pressure regulating cylinder 2. When it is necessary to evacuate 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.

[0070] The sealing ring 12 on the side of the piston 21 ensures that when the piston 21 moves in the pressure regulating cylinder 2, the oil and gas inside the cylinder will not leak and maintain good sealing. The entire system can establish and maintain a stable positive pressure environment inside the oil-immersed device 5 through precise valve control and pressure regulation mechanism to test its sealing performance.

[0071] Example 2: A positive pressure sealing test device for oil immersed equipment 5 based on Example 1, in actual use:

[0072] Due to the special structure of the oil-immersed equipment 5 of the internal oil type metal bellows oil storage cabinet, the metal bellows cannot withstand external force, so it is impossible to apply pressure to the body of the oil-immersed equipment 5 through the metal bellows to perform an overall sealing test.

[0073] The pressure regulating cylinder 2 is made of steel casting type cylinder, and its joint is 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.

[0074] After placing the positive pressure sealing test device at the test site, connect the pressure regulating cylinder 2 with the manual air pump and tighten the joints. After connecting the pressure regulating cylinder 2 with 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;

[0075] Check that the upper body butterfly valve and the lower body gate valve 42 of the oil-immersed equipment 5 are in the closed state;

[0076] Open the exhaust valve and vacuum pump interface, start the vacuum pump to evacuate the connected pipeline until the vacuum meets the requirements, and then close the exhaust valve and vacuum pump interface.

[0077] The oil-immersed device 5, the main body butterfly valve and the main body gate valve 42 are in a closed state. Before use, first connect the vacuum pump pipeline to the exhaust valve and vacuum pipe interface, and evacuate the pressure regulating cylinder 2 and the entire pipeline. Then slowly open the main body gate valve 42 at the bottom of the oil-immersed device 5 to allow the insulating oil to fill the entire high-pressure oil pipe and the pressure regulating cylinder 2, and the piston 21 in the pressure regulating cylinder 2 moves to the right side of the cylinder under the push of the oil pressure.

[0078] 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 body gate valve 42 at the bottom of the oil-immersed equipment 5. Then open the main body butterfly valve at the top of the oil-immersed equipment 5.

[0079] Inject air into the pressure regulating cylinder 2 through a 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 leakage in the high-pressure pipe and each connecting part. After confirmation, record the data of the second pressure gauge 62 and the first pressure gauge 61 and keep them for 24 hours.

[0080] Through 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.

[0081] After the test, 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 oil stains on the work site and the surface of the equipment, remove the test equipment from the work site, and record and confirm them one by one;

[0082] In this embodiment:

[0083] 1. All the 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 pipe, and the second and first pressure gauges 61 must be dried and cleaned before use;

[0084] 2. Check the connection status of each joint at any time during the test;

[0085] 3. During the test, it is strictly forbidden to allow the tested oil-immersed equipment 5 to get wet or bring air into the body of the device;

[0086] 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 it is configured as an internal oil type metal bellows oil storage cabinet.

[0087] 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 diameter does not match the test equipment, a matching joint assembly needs to be processed in advance.

[0088] 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.

[0089] The test process of this embodiment is as follows:

[0090] Step (1) Check and restore the position of the piston 21. Connect a vacuum suction pump to the valve interface of the right 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.

[0091] 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 a closed state, check that the butterfly valve between the body and the oil pillow is in a closed state, and connect the high-pressure oil pipe between the pressure regulating cylinder 2 and the body oil tank;

[0092] Step (3) First check the status of each valve of the device. Then connect the vacuum suction pump pipeline to the "exhaust valve and vacuum pipe interface", and evacuate the "pressure regulating cylinder 2" and the entire high-pressure pipeline to ensure that all moisture in the pipeline is extracted by the vacuum suction pump.

[0093] 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.

[0094] 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 oil leakage at each joint;

[0095] Step (6) Open the butterfly valve on the top of the oil-immersed equipment 5.

[0096] Step (7) Check whether the piston 21 in the "pressure regulating cylinder 2" moves to the left side of the cylinder normally under the push of air pressure. Observe the pressure value of the pressure gauge on the pressure regulating cylinder 2.

[0097] 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 0.03Mpa 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 main body of the oil-immersed equipment 5 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.

[0098] 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.

[0099] 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 the oil stains on the equipment surface, evacuate the test equipment from the work site, and record and confirm them one by one.

[0100] Finally, it should be noted that the above has been combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the utility model, so as to fully understand the purpose, characteristics and effects of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the utility model. 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 formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the creation of the utility model can be combined interactively without conflicting with each other.

Claims

1. A positive pressure seal test device for oil immersed equipment, directly connected and installed with the oil circuit system of the oil immersed equipment (5), characterized in that include: The 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), which is connected to an oil circuit system of an oil immersed device (5) through a high pressure oil circuit system, and can provide positive pressure to the body of the oil immersed device (5); The oil circuit system comprises 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) close to the oil inlet (51); a main body gate valve (42) installed on one end of the high-pressure main oil pipe (31) close to the oil outlet (52); a first check valve (43) installed on the high-pressure branch oil pipe (32); a second check valve (44) installed at the tail end of the pressure regulating cylinder (2); an external air pump (1) connected to the second check valve (44) and then connected to the pressure regulating cylinder (2); a first exhaust valve and vacuum pump interface (45) is installed on the end of the first check valve (43); and a second exhaust valve and vacuum pump interface (46) is installed on the end of the second check valve (44); When the second exhaust valve and vacuum pump interface (46) is connected to the vacuum pump pipeline, the vacuum pump can be used to reposition the piston; When the first exhaust valve and vacuum pump interface (45) is connected to the vacuum extraction pipeline, it is used to extract vacuum in the high-pressure main oil pipe (31), the high-pressure branch oil pipe (32) and the pressure regulating cylinder (2).

2. The positive pressure sealing test device for oil immersed equipment according to claim 1 is 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-bearing side to detect and display 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 is 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 is 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 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).

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).

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