An oil-immersed transformer bushing test oil temperature control system

Abstract

The utility model discloses an oil-immersed transformer bushing test oil temperature control system, including temperature rise test oil groove, circulating pump, heating branch and bypass branch, and the oil inlet of circulating pump is connected with the oil pumping port of temperature rise test oil groove, and the oil outlet of circulating pump is connected with pump out pipe, and the oil return port of temperature rise test oil groove is connected with the oil return pipe, and heating branch and bypass branch are in parallel, and heating branch includes heat regulating pipe, and the oil inlet of heat regulating pipe is communicated with the oil outlet of pump out pipe through pipe A, and the oil outlet of heat regulating pipe is communicated with the oil inlet of oil return pipe through pipe B, and bypass branch includes the communication pipe, and the oil inlet of communication pipe is communicated with the oil outlet of pump out pipe through pipe C, and the oil outlet of communication pipe is communicated with the oil inlet of oil return pipe through pipe D, and electronic ball valve is equipped on pipe A, pipe B, pipe C and pipe D respectively. The utility model discloses an oil-immersed transformer bushing test oil temperature control system can make mineral oil in temperature rise test oil groove accurate maintenance at preset temperature.

Description

Technical Field

[0001] This utility model relates to the field of power equipment testing technology, specifically to an oil temperature control system for testing bushings of oil-immersed transformers. Background Technology

[0002] Transformer bushings are the main external insulation devices of transformer tanks, and their temperature rise performance is a key indicator for evaluating product quality and safe operation. National standard GB / T4109-2022 and international standard IEC60137:2017 clearly stipulate that when conducting temperature rise tests on transformer bushings used in mineral oil, the oil temperature at the immersion end should be strictly maintained at a constant temperature 60±2℃ higher than the ambient temperature. This requirement aims to simulate the highest oil temperature hotspot conditions encountered by the bushing in actual transformer operation, thereby accurately assessing its long-term operational reliability.

[0003] Currently, the common method used in China for such tests is to use an open or simply insulated test oil tank. The basic principle is to first heat the test oil to the target temperature, then immerse the bushing and begin the electrical test. However, this method has technical drawbacks: during the test, the energized bushing acts as a continuous heat source, dissipating heat into the transformer oil, while the test oil tank itself also loses heat to the surrounding air through the tank walls and oil surface. Since the heating power of the bushing varies depending on the test sample, and the heat dissipation conditions of the oil tank are unstable, it is difficult to maintain a stable oil temperature. To approximate the standard requirements as closely as possible, test personnel have to resort to primitive methods such as frequent replacement of high-temperature oil or auxiliary heating.

[0004] However, frequent oil changes or intermittent heating lead to significant oil temperature fluctuations, often deviating from the standard requirement of 60℃±2℃ higher than ambient temperature. This prevents the formation of a stable and uniform temperature field, making the test results inaccurate in reflecting the casing's temperature rise performance. Furthermore, the oil change process is cumbersome, requiring repeated pipe connections and pump restarts, greatly reducing test efficiency. In addition, frequent oil line connections and disconnections, along with the operation of open oil tanks, easily lead to hot oil leaks and splashes, resulting in oil stains throughout the test site. This not only wastes mineral oil and pollutes the environment but also poses personal safety threats to test personnel, such as burns, slips, and falls, and also creates a fire hazard. Utility Model Content

[0005] In view of this, the present invention proposes a temperature control system for the test oil of an oil-immersed transformer bushing, so as to accurately maintain the mineral oil in the temperature rise test oil tank at a preset temperature.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A temperature control system for testing bushing oil in an oil-immersed transformer includes a temperature rise test oil tank and a circulating pump. The inlet of the circulating pump is connected to the outlet of the temperature rise test oil tank via an oil extraction pipe. The outlet of the circulating pump is connected to a pump outlet pipe. The return outlet of the temperature rise test oil tank is connected to a return oil pipe. An oil temperature sensor A is installed in the temperature rise test oil tank. The system also includes a heating branch and a bypass branch, which are connected in parallel. The heating branch includes a heat-adjusting pipe. The inlet of the heat-adjusting pipe is connected to the outlet of the pump outlet pipe via pipe A, and the outlet of the heat-adjusting pipe is connected to the inlet of the return oil pipe via pipe B. The bypass branch includes a connecting pipe. The inlet of the connecting pipe is connected to the outlet of the pump outlet pipe via pipe C, and the outlet of the connecting pipe is connected to the inlet of the return oil pipe via pipe D. Electronic ball valves are installed on pipes A, B, C, and D respectively.

[0008] To better implement the above technical solution, optionally, an oil outlet ball valve is provided on the oil extraction pipe.

[0009] Optionally, a return oil ball valve is provided on the return oil pipe.

[0010] Optionally, the pump outlet pipe is equipped with an oil temperature sensor B for detecting the mineral oil outlet temperature.

[0011] Optionally, the return oil pipe is equipped with an oil temperature sensor C for detecting the return oil temperature.

[0012] Optionally, the circulating pump is a high-flow, low-pressure peristaltic pump, and its pump pipe is made of high-temperature resistant heat-insulating material.

[0013] Optionally, the pump body of the circulating pump is equipped with an air-cooled heat dissipation device.

[0014] The beneficial effects of this utility model are:

[0015] This utility model discloses an oil temperature control system for testing bushings of oil-immersed transformers. By setting up parallel heating and bypass branches and configuring four controlled electronic ball valves, it achieves rapid switching between heating and pure circulation operating modes. Compared with traditional intermittent heating or oil change temperature control methods, this system has higher control accuracy, and oil temperature fluctuations can be controlled within ±2℃. It also avoids frequent oil changes, making operation safer, reducing mineral oil waste, and making operation more economical. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an oil-immersed transformer bushing test oil temperature control system according to an embodiment of the present invention;

[0017] Figure label:

[0018] Temperature rise test oil tank 10, circulating pump 20, heat control pipe 30, connecting pipe 40, oil extraction pipe 51, oil return pipe 52, pump outlet pipe 53, pipe A 54, pipe B 55, pipe C 56, pipe D 57, electronic ball valve 61, oil outlet ball valve 62, oil return ball valve 63, oil temperature sensor A 71, oil temperature sensor B 72, oil temperature sensor C 73, transformer bushing 80. Detailed Implementation

[0019] The technical solution of this utility model will be described in detail below with reference to the accompanying drawings and specific embodiments. Identical components are indicated by the same reference numerals.

[0020] Please see Figure 1 This utility model discloses a test oil temperature control system for oil-immersed transformer bushings, including a temperature rise test oil tank 10, a circulating pump 20, a heating branch and a bypass branch, wherein the heating branch and the bypass branch are connected in parallel.

[0021] like Figure 1 As shown, the oil inlet of the circulating pump 20 is connected to the oil outlet of the temperature rise test oil tank 10 through the oil extraction pipe 51. The oil outlet of the circulating pump 20 is connected to the pump outlet pipe 53, and the oil return port of the temperature rise test oil tank 10 is connected to the oil return pipe 52. The heating branch includes a heat control pipe 30. The oil inlet of the heat control pipe 30 is connected to the oil outlet of the pump outlet pipe 53 through pipe A54. The oil outlet of the heat control pipe 30 is connected to the oil inlet of the oil return pipe 52 through pipe B55. The bypass branch includes a connecting pipe 40. The oil inlet of the connecting pipe 40 is connected to the oil outlet of the pump outlet pipe 53 through pipe C56. The oil outlet of the connecting pipe 40 is connected to the oil inlet of the oil return pipe 52 through pipe D57. Electronic ball valves 61 are respectively installed on pipes A54, B55, C56 and D57.

[0022] Specifically, the temperature rise test oil tank 10, the oil extraction pipe 51, the circulation pump 20, the pump outlet pipe 53, the heating branch, and the return oil pipe 52 are connected in sequence to form a heating circuit; the temperature rise test oil tank 10, the oil extraction pipe 51, the circulation pump 20, the pump outlet pipe 53, the bypass branch, and the return oil pipe 52 are connected in sequence to form a bypass circuit. The temperature rise test oil tank 10 is equipped with an oil temperature sensor A71, which is used to monitor the temperature of the mineral oil in the temperature rise test oil tank 10.

[0023] In this embodiment, the heat-regulating tube 30 is essentially an electric heating tube, with an internal heating element (such as a heating wire) for actively heating the mineral oil flowing through it. The connecting tube 40 is a common metal or heat-resistant insulating pipe without any heating element; its function is solely to provide a fluid passage. The inner diameters of the heat-regulating tube 30 and the connecting tube 40 are equal to ensure that the flow resistance characteristics of the heating branch and the bypass branch are similar, thereby ensuring stable system flow when switching circuits. Both the heat-regulating tube 30 and the connecting tube 40 are commercially available standard parts, and their specific structures will not be described in detail.

[0024] During the temperature rise performance testing of transformer bushing 80, when the system needs to heat the mineral oil, the PLC controller closes the electronic ball valves 61 on pipes C56 and D57 to cut off the bypass circuit, and simultaneously opens the electronic ball valves 61 on pipes A54 and B55 to establish a heating circuit. The circulating pump 20 drives the mineral oil to flow along the heating circuit, where it is heated as it flows through the heat control tube 30 before returning to the temperature rise test oil tank 10, thus achieving a continuous increase in oil temperature. When the oil temperature reaches the set value (e.g., 60°C higher than the ambient temperature) and needs to be maintained, or when heating is not required, the PLC controller opens the electronic ball valves 61 on pipes C56 and D57 to establish a bypass circuit, and simultaneously closes the electronic ball valves 61 on pipes A54 and B55 to cut off the heating circuit. The mineral oil then switches to flowing through the bypass circuit, where it only circulates without being heated, effectively preventing overheating of the oil caused by residual heat from the heat control tube 30 or continuous heating. The above solution replaces the traditional method of temperature control by frequently starting and stopping the heating element or changing a lot of oil by physically switching the circuit. It achieves precise and stable control of mineral oil temperature, and in particular, it can keep the oil temperature precisely stable at a constant temperature of 60±2℃ higher than the ambient temperature, which meets the strict requirements of the standard temperature rise test.

[0025] In this embodiment, the oil extraction pipe 51 is provided with an oil outlet ball valve 62, and the oil return pipe 52 is provided with an oil return ball valve 63. The oil outlet ball valve 62 and the oil return ball valve 63 serve as the main isolation valves of the system, which facilitates equipment maintenance, repair or isolation.

[0026] In this embodiment, the pump outlet pipe 53 is equipped with an oil temperature sensor B72 for detecting the mineral oil outlet temperature, and the return oil pipe 52 is equipped with an oil temperature sensor C73 for detecting the return oil temperature. The signal output terminals of the oil temperature sensor A71, temperature sensor B72, and temperature sensor C73 are all electrically connected to the signal input terminal of the PLC controller. The PLC controller can collect and compare the temperature data of each key node in the pipeline and inside the oil tank in real time, and based on this, through PID and other control algorithms, not only control the switching of the electronic ball valve 61, but also dynamically adjust the heating power of the heat control tube 30. The multi-sensor feedback closed-loop control strategy improves the system's response speed and control accuracy, thereby enabling the oil temperature in the temperature rise test oil tank 10 to be maintained within the set range more quickly and accurately.

[0027] During the test, the oil temperature in the temperature rise test oil tank 10 is relatively high (generally between 65℃ and 95℃). When ordinary centrifugal pumps or gear pumps drive the high-temperature mineral oil circulation for a long time, the stability is prone to decrease due to problems such as sealing and lubrication. Therefore, preferably, the circulation pump 20 is a high-flow-rate low-pressure peristaltic pump. The peristaltic tube of the peristaltic pump is made of heat-resistant and heat-insulating material. The pump body of the circulation pump 20 is equipped with an air-cooling device, such as a cooling fan. The cooling fan forces the pump body to dissipate heat, so that the core components of the pump head can be kept within their rated operating temperature range for a long time. This ensures the long-term stable operation of the circulation pump 20 under high-temperature conditions from the source.

[0028] This utility model discloses an oil-immersed transformer bushing test oil temperature control system. By setting up parallel heating and bypass branches and configuring four controlled electronic ball valves 61, it realizes rapid switching between heating and pure circulation working modes. Compared with traditional intermittent heating or oil change temperature control methods, this system has higher control accuracy, and the oil temperature fluctuation can be controlled within ±2℃. It also avoids frequent oil changes, making operation safer and more economical.

[0029] The technical solution of this utility model has been described in detail above with reference to specific embodiments. The specific embodiments described are used to help understand the concept of this utility model. Derivations and modifications made by those skilled in the art based on the specific embodiments of this utility model also fall within the protection scope of this utility model.

Claims

1. A test oil temperature control system for an oil-immersed transformer bushing, comprising a temperature rise test oil tank (10) and a circulating pump (20), wherein the oil inlet of the circulating pump (20) is connected to the oil outlet of the temperature rise test oil tank (10) via an oil extraction pipe (51), the oil outlet of the circulating pump (20) is connected to a pump outlet pipe (53), the oil return port of the temperature rise test oil tank (10) is connected to a return oil pipe (52), and an oil temperature sensor A (71) is provided inside the temperature rise test oil tank (10), characterized in that: It also includes a heating branch and a bypass branch, wherein the heating branch and the bypass branch are connected in parallel. The heating branch includes a heat-adjusting pipe (30), the oil inlet of the heat-adjusting pipe (30) is connected to the oil outlet of the pump outlet pipe (53) through pipe A (54), and the oil outlet of the heat-adjusting pipe (30) is connected to the oil inlet of the return oil pipe (52) through pipe B (55). The bypass branch includes a connecting pipe (40), the oil inlet of the connecting pipe (40) is connected to the oil outlet of the pump outlet pipe (53) through pipe C (56), and the oil outlet of the connecting pipe (40) is connected to the oil inlet of the return oil pipe (52) through pipe D (57). Electronic ball valves (61) are respectively provided on pipe A (54), pipe B (55), pipe C (56) and pipe D (57).

2. The oil temperature control system for testing bushings of an oil-immersed transformer according to claim 1, characterized in that, The oil extraction pipe (51) is equipped with an oil outlet ball valve (62).

3. The oil temperature control system for testing bushings of an oil-immersed transformer according to claim 1, characterized in that, The return oil pipe (52) is equipped with a return oil ball valve (63).

4. The oil temperature control system for testing bushings of an oil-immersed transformer according to claim 1, characterized in that, The pump outlet pipe (53) is equipped with an oil temperature sensor B (72) for detecting the mineral oil outlet temperature.

5. The oil temperature control system for testing bushings of an oil-immersed transformer according to claim 1, characterized in that, The return oil pipe (52) is equipped with an oil temperature sensor C (73) for detecting the return oil temperature.

6. The oil temperature control system for testing bushings of an oil-immersed transformer according to claim 1, characterized in that, The circulating pump (20) is a high-flow, low-pressure peristaltic pump, and its pump pipe is made of high-temperature resistant heat-insulating material.

7. The oil temperature control system for testing bushings of an oil-immersed transformer according to claim 6, characterized in that, The circulating pump (20) is equipped with an air-cooled heat dissipation device.

Images