A method and apparatus for calibrating a temperature gauge for an oil-immersed transformer.

Abstract

This invention discloses a calibration method and apparatus for an oil-immersed transformer temperature gauge. The calibration method includes the following steps: S100: Temperature calibration point selection: Selecting several temperature calibration points within the actual operating range of the temperature gauge and between the actual maximum operating value and the maximum value displayed on the temperature gauge dial; S200: Temperature calibration point calibration: Conducting a heating test using the calibration apparatus, performing temperature change simulation tests on each individual temperature calibration point; S300: Verifying the ambient temperature compensation adjustment function of the temperature gauge: Performing a heating simulation ambient temperature test by wrapping a heating wire around the temperature gauge's tubing, performing ambient temperature change simulation tests on at least three temperature calibration points. This invention's calibration method, by selecting temperature calibration points within the actual operating range of the temperature gauge and considering the impact of ambient temperature changes on the temperature gauge's stability, comprehensively calibrates the single-point temperature calibration and environmental impact functions of the temperature gauge, identifying and correcting various potential problems with the temperature gauge in advance.

Description

Technical Field

[0001] This invention relates to the field of performance testing technology for oil-immersed transformer temperature gauges, and particularly to a calibration method and apparatus for oil-immersed transformer temperature gauges. Background Technology

[0002] Oil-immersed transformers use insulating oil as the cooling medium. According to the six degrees rule, once the transformer oil temperature exceeds 60 degrees Celsius, its lifespan will decrease by half for every 6 degrees Celsius increase in temperature. To ensure the cooling effect of the cooling system, multiple temperature gauges are installed on the transformer casing to monitor its operating temperature. However, during the operation of oil-immersed transformers, several problems have occurred, including large jumps in temperature gauge readings, poor environmental adaptability, and large discrepancies between temperature gauges, causing numerous inconveniences in accurately determining the transformer's operating temperature.

[0003] To ensure the performance of the thermometer and minimize malfunctions, its performance needs to be calibrated before installation. Current calibration methods involve comparing measurements at a few scattered temperature points across the entire measurement range. This method has the following problems:

[0004] 1. The actual operating range of the thermometer and the impact of ambient temperature changes on the stability of the thermometer were not considered when selecting the temperature points for comparative measurements. This may lead to deviations between the measured results and the actual operating conditions.

[0005] 2. Only a single temperature gauge can be used for detection. The performance of multiple temperature gauges in the same transformer system may vary, which brings great difficulties to temperature monitoring during transformer operation. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and apparatus for calibrating a temperature gauge for an oil-immersed transformer.

[0007] The technical solution adopted by this invention to solve its technical problem is: a method and apparatus for calibrating a temperature gauge for an oil-immersed transformer, comprising the following steps:

[0008] S100: Temperature calibration point selection: Select several temperature calibration points within the actual operating range of the temperature gauge and between the actual operating maximum value and the maximum value displayed on the temperature gauge dial.

[0009] S200: Temperature calibration point calibration: A heating test is performed using a calibration device. Temperature change simulation test is performed on each of the individual temperature calibration points, and the dial display value X1 of the temperature gauge and the temperature display value Y1 of the calibration device are observed for each individual temperature calibration point.

[0010] If X1-Y1 of any temperature verification point is (-1 to 1)℃, then all temperature verification points are qualified and proceed to the next step; if X1-Y1 of a single temperature verification point is not equal to (-1 to 1)℃, then the temperature verification point is unqualified and is returned to the factory; if X1-Y1 of at least two temperature verification points is not equal to (-1 to 1)℃, and X1-Y1 of at least two temperature verification points is less than -1℃ or greater than 1℃, then the temperature is calibrated by adjusting the pointer knob of the thermometer and proceed to the next step.

[0011] S300: Verification of the ambient temperature compensation adjustment function of the thermometer: Use a heating ribbon to wrap around the tubing of the thermometer to conduct a heating simulation ambient temperature test. Perform ambient temperature change simulation tests on at least 3 of the temperature verification points respectively, and observe the dial display value X2 of the thermometer and the display value Y2 of the verification device at each of the individual temperature verification points. At the same time, check the pointer condition of the thermometer.

[0012] If X2-Y2 = (-1 to 1)℃ at any of the temperature calibration points, and the pointer of the thermometer does not jitter or does not jitter after calibration, then the ambient temperature compensation adjustment function of the thermometer is qualified; if X2-Y2 ≠ (-1 to 1)℃ at any of the temperature calibration points, or if the pointer still jitters after calibration, then the ambient temperature compensation adjustment function of the thermometer is unqualified and it should be returned to the factory.

[0013] Preferably, in the calibration method for the oil-immersed transformer temperature gauge of the present invention, step S100 includes the following sub-steps:

[0014] S110: Read the dial data of the temperature gauge and define the maximum value displayed on the dial as temperature point t1;

[0015] S120: Retrieve the operating history of the temperature gauge described above, and take the highest operating temperature within the past 5 years as temperature point t2;

[0016] S130: Select several temperature verification points at equal intervals within the range of 0 to t2, and select the first temperature verification point at equal intervals outside the range of t2;

[0017] S140: Select at least 3 temperature verification points within the range of t2 to t1, including t2, t1-10℃ and (t1-10℃+t2).

[0018] Preferably, in the calibration method of the oil-immersed transformer temperature gauge of the present invention, in step S130, t1 / 10℃ is rounded to m, with a spacing of 2m; the values ​​of the several temperature calibration points are 2m, 4m, 6m, ..., *2m; where *2m > t2.

[0019] Preferably, in the calibration method for the oil-immersed transformer temperature gauge of the present invention, step S200 includes the following sub-steps:

[0020] S210: Remove the probe of the temperature gauge and place the probe into the calibration device;

[0021] S220: Heat the calibration device until its temperature display value matches any of the temperature calibration points, then stop heating;

[0022] S230: Close the calibration device to maintain the temperature, and after a certain period of time, record the dial display value X1 of the temperature gauge and the temperature display value Y1 of the calibration device;

[0023] S240: Repeat steps S220 and S230 multiple times until all the temperature verification points have been experienced once, then stop repeating.

[0024] S250: Calculate and compare the results of X1-Y1 at each of the temperature verification points;

[0025] If X1-Y1 = (-1 to 1)℃ at any of the temperature verification points, then all the temperature verification points are qualified and proceed to the next step; if X1-Y1 ≠ (-1 to 1)℃ at a single temperature verification point, or if X1-Y1 ≠ (-1 to 1)℃ at at least two temperature verification points and the result of X1-Y1 includes both positive and negative numbers, then the temperature verification point is unqualified and is returned to the factory; if X1-Y1 ≠ (-1 to 1)℃ at at least two temperature verification points and the result of X1-Y1 is either positive or negative, then the pointer is corrected by adjusting the pointer knob and proceed to the next step.

[0026] Preferably, in the calibration method of the oil-immersed transformer temperature gauge of the present invention, in step S250, if it is found that X1-Y1 ≠ (-1~1)℃ at a single temperature calibration point, the calibration device is heated again until its temperature display value is consistent with the single calibration temperature point, and then the heating is stopped; steps S230 and S250 are repeated.

[0027] Preferably, in the calibration method of the oil-immersed transformer temperature gauge according to the present invention, in step S250, if X1-Y1≠(-1~1)℃ at at least two of the temperature calibration points and the result of X1-Y1 is negative or positive, then half of the result of the maximum deviation value minus the minimum deviation value is taken as the standard value, and the temperature gauge pointer is adjusted upward or downward to the standard value; S200 is repeated to verify the calibration effect;

[0028] If the maximum deviation is ≤2℃ after repeating S200, the temperature gauge calibration is complete.

[0029] Preferably, in the calibration method for the oil-immersed transformer temperature gauge of the present invention, step S300 includes the following sub-steps:

[0030] S310: Verify the ambient temperature compensation adjustment function of the pipeline between the probe and the head of the thermometer; use the heating ribbon to unevenly wrap around the entire pipeline, use the verification device to heat to any of the temperature verification points and heat the heating ribbon, observe the display value X21 of the thermometer dial and the temperature display value Y21 of the heating verification device, and check the pointer of the thermometer at the same time.

[0031] If X21-Y21 = (-1 to 1)℃ and the pointer does not fluctuate, the ambient temperature compensation and adjustment function of the pipeline across the entire range is qualified and proceeds to the next step; if X21-Y21 ≠ (-1 to 1)℃, the ambient temperature compensation and adjustment function of the pipeline across the entire range is unqualified and the pipeline is returned to the factory; if the pointer fluctuates, proceed to the next step after calibrating the pointer.

[0032] S320: Verify the ambient temperature compensation adjustment function of the pipeline near the probe between the probe and the meter head of the thermometer; wrap the heating ribbon around the pipeline near the probe, use the verification device to heat to any of the temperature verification points and heat the heating ribbon, observe the dial display value X22 of the thermometer and the temperature display value Y22 of the verification device, and check the pointer of the thermometer at the same time.

[0033] If X22-Y22 = (-1 to 1)℃ and the pointer does not jitter, then the ambient temperature compensation adjustment function of the pipeline near the probe is qualified and proceeds to the next step; if X22-Y22 ≠ (-1 to 1)℃, then the ambient temperature compensation adjustment function of the pipeline near the probe is unqualified and it is returned to the factory; if the pointer jitters, then proceed to the next step after calibrating the pointer.

[0034] S330: Verify the ambient temperature compensation adjustment function of the pipeline between the probe and the meter head of the thermometer near the meter head; wrap the heating ribbon around the pipeline near the meter head, use the verification device to heat to any of the temperature verification points and heat the heating ribbon, observe the display value X23 of the thermometer dial and the display value Y23 of the verification device, and check the pointer of the thermometer at the same time.

[0035] If X23-Y23 = (-1 to 1)℃ and the pointer does not jitter, then the ambient temperature compensation adjustment function of the pipeline near the meter head is qualified; if X23-Y23 ≠ (-1 to 1)℃ or the pointer jitters, then the ambient temperature compensation adjustment function of the thermometer is unqualified and it should be returned to the factory.

[0036] Preferably, in the calibration method for the oil-immersed transformer temperature gauge of the present invention, the calibration method further includes the following steps:

[0037] S400: Horizontal overall performance verification of multiple temperature gauges on the same device; heating test using the verification device and heating simulation ambient temperature test by wrapping the pipeline with the heating ribbon, while performing temperature change simulation test on multiple temperature gauges, observing the dial display value X3 of multiple temperature gauges respectively, and checking the pointer condition of the temperature gauges.

[0038] If, under the same heating temperature, the dial display value X3 of the multiple temperature gauges is X3 max -X3 min If the temperature is ≤2℃ and the pointer does not jitter, then the overall lateral performance test of the multiple temperature gauges is qualified; if, under the same heating temperature, the dial display value of the multiple temperature gauges is X3 out of X3... max -X3 min If the temperature exceeds 2°C or the pointer fluctuates, multiple temperature gauges need to be calibrated and the overall performance test of multiple temperature gauges on the same device should be repeated.

[0039] Preferably, in the calibration method for the oil-immersed transformer temperature gauge of the present invention, step S400 includes the following sub-steps:

[0040] S410: Place the probes of multiple temperature gauges in the same calibration device;

[0041] S420: Start the calibration device and heat it to a random temperature value. After the temperature display value of the calibration device stabilizes, read the dial display value X31 of the temperature gauge and observe the magnitude of the dial display value X31 of each temperature gauge.

[0042] S430: Repeat step S420 multiple times;

[0043] If, under the same heating temperature, the dial display value X31 of multiple temperature gauges is X31 max -X31 min If the temperature is ≤2℃, proceed to the next step; if the displayed value X31 of the dials of multiple temperature gauges is ≤2℃ under the same heating temperature, then proceed to the next step. max -X31 minIf the temperature is >2℃, then after calibrating the multiple temperature gauges, repeat step S420;

[0044] S440: Use heating ribbons to wrap around the same position of multiple thermometers, heat the heating ribbons, read the dial display value X32 of multiple thermometers, observe the size of the dial display value X32 of each thermometer and check the pointer jitter of each thermometer.

[0045] Use heated ribbons to wrap around different positions of multiple thermometers, heat the ribbons, read the dial display value X33 of multiple thermometers, observe the size of the dial display value X33 of each thermometer and check the pointer jitter of each thermometer.

[0046] If, under the same heating temperature, the dial display value X32 of multiple temperature gauges is X32 max -X32 min ≤2℃ and X33 in X33 max -X33 min If the temperature is ≤2℃ and the pointer of any one of the thermometers does not jitter, then the overall lateral performance test of the multiple thermometers is qualified; if, under the same heating temperature, the dial display value of the multiple thermometers is X32, then X32... max -X32 min >2℃, X33 max -X33 min If the temperature exceeds 2°C or the pointer of any of the aforementioned temperature gauges jitters, then multiple temperature gauges need to be calibrated and the overall lateral performance test of multiple temperature gauges on the same device needs to be repeated.

[0047] The technical solution adopted by the present invention to solve its technical problem also includes: a verification device, used in any of the verification methods described above, wherein the verification device includes a housing, an oil storage heating tank, a thermometer, a temperature display and a heating module;

[0048] The oil storage heating tank and heating module are located inside the housing; the heating module is connected to the oil storage heating tank to heat the oil storage heating tank; the thermometer is located inside the oil storage heating tank to detect the temperature inside the oil storage heating tank; the temperature display is connected to the thermometer to display the temperature value of the thermometer in real time.

[0049] By implementing this invention, the following beneficial effects are achieved:

[0050] The calibration method for the oil-immersed transformer temperature gauge of the present invention selects temperature calibration points within the actual operating range of the temperature gauge and considers the impact of ambient temperature changes on the stability of the temperature gauge. It comprehensively calibrates the single-point temperature calibration and environmental impact functions of the temperature gauge, which can identify various potential problems of the temperature gauge in advance and correct them in time, greatly improving the operational stability of the temperature gauge. Attached Figure Description

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0052] Figure 1 This is a flowchart of a method for calibrating a temperature gauge for an oil-immersed transformer according to an embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram of the structure of a verification device according to an embodiment of the present invention;

[0054] Figure 3 This is the present invention. Figure 2 A schematic diagram of the use of the verification device. Detailed Implementation

[0055] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0056] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0057] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0058] See Figure 1 One embodiment of the present invention discloses a calibration method for an oil-immersed transformer temperature gauge, which can be used to comprehensively calibrate the single-point temperature calibration and environmental impact function of the temperature gauge, and identify and correct various potential problems of the temperature gauge in advance.

[0059] The verification method includes the following steps in some embodiments:

[0060] S100: Temperature Calibration Point Selection: Select several temperature calibration points within the actual operating range of the temperature gauge and between the actual maximum operating value and the maximum value displayed on the temperature gauge dial. Generally, the display range of the temperature gauge dial is much higher than its actual operating range. With the improvement of the efficiency of oil-immersed transformers, the normal operating range of transformer oil temperature has further decreased, far below its displayable range. Therefore, focusing on points within the actual operating range when selecting temperature gauge calibration points can improve the accuracy of temperature gauge calibration tests.

[0061] Further, in some embodiments, S100 includes the following sub-steps: S110: Read the dial data of the temperature gauge and define the maximum value displayed on the dial as temperature point t1. S120: Retrieve the operating history of similar temperature gauges and take the highest operating temperature within 5 years as temperature point t2. Similar temperature gauges refer to the same model of temperature gauges that were previously used for monitoring the same location on oil-immersed transformers, and the actual temperature ranges they monitor are generally quite similar. S130: Select several temperature verification points at equal intervals within the range of 0 to t2 and select the first temperature verification point at equal intervals outside the range of t2. Preferably, in some embodiments, the interval is determined as follows: t1 / 10℃ is rounded down to m, with 2m as the interval; the values ​​of the several temperature verification points are 2m, 4m, 6m, ..., *2m; where *2m > t2. Understandably, t1 / 10℃ rounded to m, with 2m as the interval, is only one example of the present invention. In some other embodiments, the choice of interval is not unique, but varied. For example, t1 / 20℃ rounded to n, with n as the interval, and other methods for determining the interval can be selected. S140: Select at least 3 temperature verification points in the range of t2 to t1, including t2, t1-10℃, and (t1-10℃+t2).

[0062] S200: Temperature Calibration Point Verification: A heating test is performed using a calibration device. Temperature change simulation tests are conducted on individual temperature calibration points, and the dial display value X1 of the thermometer at each calibration point and the temperature display value Y1 of the calibration device are observed. Understandably, the calibration device itself is a heatable device or a device that can be externally heated. To measure the real-time temperature within the calibration device, a thermometer can be installed inside the device, and a display device can be connected externally to obtain the temperature inside the device. Preferably, for ease of operation and time saving, temperature change simulation tests are performed on all temperature calibration points selected in step S100 one by one, with the simulation tests arranged from lowest to highest temperature. Of course, in other embodiments, a cooling structure or an external cooling device can be provided in the calibration device, and the temperature arrangement does not need to be from lowest to highest, which can also save inspection time.

[0063] If X1-Y1 = (-1 to 1)℃ at any temperature calibration point, that is, the difference between the dial display value X1 of the temperature gauge at any temperature calibration point and the temperature display value Y1 of the calibration device needs to fall within the range of -1 to 1. For example, if there are 3 temperature calibration points, X1-Y1 = -1℃ for temperature calibration point 1, X1-Y1 = -0.5℃ for temperature calibration point 2, and X1-Y1 = 1℃ for temperature calibration point 3, and the difference between the dial display value X1 of these 3 temperature calibration points and the temperature display value Y1 of the calibration device all fall within the range of -1 to 1, then all temperature calibration points are qualified and the next step can be performed. If X1-Y1 of a single temperature calibration point ≠ (-1 to 1)℃, that is, after testing all temperature calibration points, it is found that the difference between the dial display value X1 of only one temperature calibration point and the temperature display value Y1 of the calibration device does not fall within the range of -1 to 1. For example, if there are 3 temperature calibration points, X1-Y1 of temperature calibration point 1 is -1℃, X1-Y1 of temperature calibration point 2 is -0.5℃, and X1-Y1 of temperature calibration point 3 is 1.5℃, and the difference between the dial display value X1 of temperature calibration point 3 and the temperature display value Y1 of the calibration device does not fall within the range of -1 to 1, then the temperature calibration point is unqualified and must be returned to the factory. If at least two temperature calibration points have X1-Y1 ≠ (-1 to 1)℃, and at least two temperature calibration points have X1-Y1 < -1℃ or X1-Y1 > 1℃, for example, if there are 3 temperature calibration points in total, and X1-Y1 of temperature calibration point 1 = -2℃, X1-Y1 of temperature calibration point 2 = 0.5℃, and X1-Y1 of temperature calibration point 3 = -1.5℃, then the calibration is performed by adjusting the pointer knob of the thermometer and proceeding to the next step. It is understood that setting 3 temperature calibration points is only one embodiment. In other embodiments, 4, 5, 8, 9, or other temperature calibration points conforming to the selection method in step S10 can be selected. This invention does not limit the number of temperature calibration points.

[0064] Furthermore, in some embodiments, S200 includes the following sub-steps:

[0065] S210: Remove the probe of the thermometer and place it into the calibration device. Understandably, the thermometer tested in this invention can be a thermometer that has not been used in an oil-immersed transformer or a thermometer that has been used in an oil-immersed transformer. When the thermometer has been used in an oil-immersed transformer, the probe of the thermometer can be removed from the oil tank on the body side of the oil-immersed transformer and then placed into the calibration device.

[0066] S220: Heat the calibration device until its temperature display value matches any temperature calibration point, then stop heating.

[0067] S230: The closed calibration device maintains the temperature to prevent rapid heat loss and large errors. After a certain period of time, the dial display value X1 of the temperature gauge and the temperature display value Y1 of the calibration device are recorded. Preferably, data recording can begin after five minutes of rest.

[0068] S240: Repeat steps S220 and S230 multiple times until all temperature verification points have been verified once, then stop repeating. Preferably, all temperature verification points are verified in ascending order of temperature value.

[0069] S250: Calculate and compare the X1-Y1 result for each temperature calibration point. If X1-Y1 = (-1 to 1)℃ for any temperature calibration point, then all temperature calibration points are qualified and proceed to the next step. If X1-Y1 ≠ (-1 to 1)℃ for a single temperature calibration point, or if X1-Y1 ≠ (-1 to 1)℃ for at least two temperature calibration points, and the X1-Y1 result includes both positive and negative numbers, then the temperature calibration point is unqualified and returned to the factory. Preferably, to prevent measurement errors, if X1-Y1 ≠ (-1 to 1)℃ for a single temperature calibration point is found, the calibration device is heated again until its temperature display value matches that single calibration temperature point, and then heating is stopped; steps S230 and S250 are repeated. If X1-Y1 ≠ (-1 to 1)℃ for the temperature calibration point after the second test, then the X1-Y1 of the temperature calibration point is not equal to (-1 to 1)℃. If X1-Y1 ≠ (-1~1)℃ at at least two temperature calibration points and the result of X1-Y1 is positive or negative, then the pointer is calibrated by adjusting the pointer knob and proceeding to the next step. Preferably, if X1-Y1 ≠ (-1~1)℃ at at least two temperature calibration points and the result of X1-Y1 is negative or positive, then half of the result of the maximum deviation value minus the minimum deviation value is used as the standard value, and the thermometer pointer is adjusted upward or downward to this standard value; S200 is repeated to verify the calibration effect; if the maximum deviation value is ≤2℃ after repeating S200, then the thermometer calibration work is completed.

[0070] Temperature gauges for oil-immersed transformers are typically installed at the bottom of the transformer casing or inside the control cabinet. The probe of the temperature gauge is installed in the oil sump at the top of the transformer, with a significant distance between them. The pipeline between the probe and the gauge head is quite long, generally designed to be greater than 10 meters. To eliminate the influence of ambient temperature on the temperature gauge readings, this pipeline is equipped with an ambient temperature compensation and adjustment pipeline. To ensure the integrity of the temperature gauge's function, step S300 is included: Validation of the ambient temperature compensation and adjustment function of the temperature gauge.

[0071] S300: Verification of the ambient temperature compensation adjustment function of the thermometer: A heating wire is used to wrap around the thermometer's tubing to simulate ambient temperature. The wire is heated to simulate ambient temperature, so it can be heated to the simulated ambient temperature, generally not exceeding 60°C. The temperature can be controlled by the number of heaters used. Then, ambient temperature change simulation tests are performed on at least three temperature calibration points, and the display value X2 of the thermometer dial and the display value Y2 of the calibration device at each temperature calibration point are observed. Simultaneously, the thermometer pointer is checked. Preferably, at least three temperature calibration points can be selected from the range of 0 to t2. The temperature values ​​of these three calibration points are heated one by one using the calibration device, which more closely approximates the actual operating environment. It is understood that step S300 can be performed simultaneously with the temperature calibration point verification in step S200. When performing the temperature change simulation test on a single temperature calibration point using the calibration device in S200, three of the temperature calibration points are selected. Of course, in some other embodiments, after completing step S200, at least three temperature calibration points from the range of 0 to t2 can be selected to verify the ambient temperature compensation adjustment function of the thermometer.

[0072] If X2 - Y2 = (-1 to 1)℃ at any temperature calibration point, and the thermometer pointer shows no fluctuation or, after calibration, shows no fluctuation, then the ambient temperature compensation adjustment function of the thermometer is qualified. If X2 - Y2 ≠ (-1 to 1)℃ at any temperature calibration point, or if the pointer still fluctuates after calibration, then the ambient temperature compensation adjustment function of the thermometer is unqualified and it must be returned to the factory. Understandably, the absence of pointer fluctuation verifies that the thermometer is less affected by ambient temperature, indicating more reliable functionality.

[0073] Furthermore, in some embodiments, S300 includes the following sub-steps:

[0074] S310: Verification of the ambient temperature compensation adjustment function of the pipeline between the probe and the head of the thermometer; by unevenly winding the heating ribbon around the pipeline, the stability of the thermometer can be randomly tested. The calibration device is used to heat any temperature calibration point and heat the heating ribbon. The display value X21 on the thermometer dial and the temperature display value Y21 of the heating calibration device are observed. At the same time, the pointer of the thermometer is checked.

[0075] If X21-Y21 = (-1 to 1)℃ and the pointer does not fluctuate, the pipeline's full-range ambient temperature compensation and adjustment function is qualified, and the next step can be performed. If X21-Y21 ≠ (-1 to 1)℃, the pipeline's full-range ambient temperature compensation and adjustment function is unqualified, and the pipeline must be returned to the factory. If the pointer fluctuates, the next step can be performed after calibrating the pointer.

[0076] Preferably, the method for calibrating the pointer is as follows: First, check the alignment of the pointer with the panel; if there is a deviation, adjust it until the entire pointer is parallel to the panel. Second, check the fixing of the thermometer pointer shaft; if it is loose, tighten it. Third, check the smoothness of the transmission gear rotation; if there is any jamming, remove the jamming. Finally, check the surface of the temperature compensation mechanism; if there are any other wires attached, remove them.

[0077] S320: Verify the ambient temperature compensation adjustment function of the pipeline near the probe between the thermometer probe and the meter head; wrap the pipeline near the probe with a heating ribbon, heat it to any temperature verification point using the verification device and heat the heating ribbon, observe the temperature display value X22 on the thermometer dial and the temperature display value Y22 on the verification device, and check the thermometer pointer at the same time.

[0078] If X22-Y22 = (-1 to 1)℃ and the pointer does not fluctuate, the ambient temperature compensation adjustment function of the pipeline near the probe is qualified and proceeds to the next step; if X22-Y22 ≠ (-1 to 1)℃, the ambient temperature compensation adjustment function of the pipeline near the probe is unqualified and the pipeline needs to be returned to the factory; if the pointer fluctuates, proceed to the next step after calibrating the pointer. The pointer calibration method is the same as above and will not be repeated here.

[0079] S330: Verify the ambient temperature compensation adjustment function of the pipeline between the thermometer probe and the meter head near the meter head; wrap the pipeline near the meter head with a heating ribbon, use the calibration device to heat to any temperature calibration point and heat the heating ribbon, observe the display value X23 on the thermometer dial and the display value Y23 on the calibration device, and check the thermometer pointer at the same time.

[0080] If X23-Y23 = (-1 to 1)℃ and the pointer does not jitter, the ambient temperature compensation adjustment function of the pipeline near the meter head is qualified; if X23-Y23 ≠ (-1 to 1)℃ or the pointer jitters, the ambient temperature compensation adjustment function of the thermometer is unqualified and it should be returned to the factory.

[0081] Preferably, when the heating ribbon is wound around the pipeline in any step of the present invention, the heating ribbon and the pipeline are in close contact to ensure the accuracy of the heating temperature, and the heating ribbon can be heated by electricity.

[0082] Understandably, the pipeline heating method based on the uniform and non-uniform winding of heating ribbons around the temperature gauge pipeline can simulate varying ambient temperatures and verify the environmental compensation function of the temperature gauge.

[0083] This invention fills a gap in related technologies. After all calibrations of a single temperature gauge have been completed and passed, a comprehensive comparison of the performance of multiple temperature gauges under the same operating conditions is performed, thereby ensuring the consistency of the monitoring data from each temperature gauge during transformer operation. Therefore, the calibration method for oil-immersed transformer temperature gauges of this invention also includes step S400: lateral overall performance calibration of multiple temperature gauges on the same device.

[0084] S400: Horizontal overall performance verification of multiple temperature gauges on the same device; heating test using a verification device and heating simulation ambient temperature test using heating ribbons wrapped around the pipeline; simultaneously performing temperature change simulation test on multiple temperature gauges, observing the dial display values ​​of multiple temperature gauges (X3), and checking the pointer condition of the temperature gauges. Preferably, the multiple temperature gauges include three or more temperature gauges.

[0085] If, under the same heating temperature, the dial displays value X3 among multiple temperature gauges... max -X3 min If the temperature is ≤2℃ and the pointer shows no jitter, then the overall lateral performance test of multiple temperature gauges is qualified. If, under the same heating temperature, the dial display values ​​of multiple temperature gauges are X3 out of X3... max -X3 min If the temperature exceeds 2°C or the pointer fluctuates, multiple thermometers need to be calibrated, and the overall performance test of multiple thermometers on the same device should be repeated. Among them, X3 max This represents the maximum value of the X3 displayed on the dials of multiple temperature gauges. min This represents the minimum value of the dial display value X3 of multiple temperature gauges.

[0086] Furthermore, in some embodiments, S400 includes the following sub-steps:

[0087] S410: Placing multiple thermometer probes in the same calibration device allows for simultaneous heating at the same temperature test point, avoiding unnecessary errors caused by using multiple calibration devices. Understandably, using the same calibration device is for achieving the same temperature simultaneously. However, in situations where placing probes in the same calibration device is inconvenient but achieving the same temperature simultaneously is possible, it is not limited to placing multiple thermometer probes in the same device; multiple thermometer probes can also be placed in two or more calibration devices.

[0088] S420: Start the calibration device and heat it to a random temperature value. After the temperature display value of the calibration device stabilizes, read the dial display value X31 of the temperature gauges and observe the magnitude of the dial display value X31 of each temperature gauge. Preferably, the random temperature value can be selected within the range of 0 to t2, which is closer to the actual working conditions. Since temperature gauges monitored at different locations may have different t2 values, any temperature gauge within the range of 0 to t2 can be selected.

[0089] S430: Repeat step S420 multiple times. If, at the same heating temperature, for the dial display values X31 of multiple thermometers, X31 max - X31 min ≤ 2°C, then proceed to the next step. If, at the same heating temperature, for the dial display values X31 of multiple thermometers, X31 max - X31 min > 2°C, then calibrate the multiple thermometers and repeat step S420. It can be understood that when calibrating in the same calibration device with a single thermometer qualified, the probability of the situation where, for the dial display values X31 of multiple thermometers, X31 max - X31 min > 2°C occurs is very low. If this situation occurs, the calibration method is as follows:

[0090] First, analyze the dial display values X31 of multiple thermometers and confirm the thermometer with the largest deviation as the analysis object; second, count the deviation data between it and other multiple thermometers during this period; finally, calculate the standard values of the multiple thermometers, and judge whether the pointer moves up or down by one standard value according to the positive or negative of the standard value. After calibrating the multiple thermometers, the thermometers are re - calibrated according to the horizontal calibration method once. For the dial display values X31 of multiple thermometers, X31 max - X31 min ≤ 3°C, the thermometer calibration work ends, and the thermometers are determined to be qualified. It can be understood that in the present invention, "upward" refers to the direction of increasing the value, and "downward" refers to the direction of decreasing the value.

[0091] S440: Use heating ribbons to wrap around the same position of multiple thermometers respectively, heat the heating ribbons, read the dial display values X32 of multiple thermometers, observe the magnitudes of the dial display values X32 of each thermometer and check the pointer jitter situation of each thermometer. Preferably, the heating ribbons are evenly wrapped around the same position of multiple thermometers in a situation where the test ambient temperature is relatively stable.

[0092] Use heating ribbons to wrap around different positions of multiple thermometers respectively, heat the heating ribbons, read the dial display values X33 of multiple thermometers, observe the magnitudes of the dial display values X33 of each thermometer and check the pointer jitter situation of each thermometer. Preferably, the heating ribbons are unevenly wrapped around different positions of multiple thermometers in a situation where the test ambient temperature is unstable.

[0093] If, at the same heating temperature, for the dial display values X32 of multiple thermometers, X32 max - X32 min ≤ 2°C and for X33 of multiple thermometers, X33 max - X33 minIf the temperature is ≤2℃ and the pointer of any one thermometer does not jitter, then the overall lateral performance test of multiple thermometers is qualified; if, under the same heating temperature, the dial display values ​​of multiple thermometers are X32, then X32 is qualified. max -X32 min >2℃, X33 max -X33 min If the temperature exceeds 2°C or the pointer of any thermometer vibrates, multiple thermometers need to be calibrated and the overall performance test of multiple thermometers on the same device should be repeated. The calibration method is the same as above and will not be repeated here.

[0094] After performing performance verification tests on the oil-immersed transformer temperature gauge using the verification method of this invention, fault points such as abnormal pipeline environmental regulation function and jamming or deformation of the temperature gauge pointer stop can be identified, eliminating potential defects that are difficult to identify using conventional methods. Simultaneously, this verification method can comprehensively test the temperature gauge performance, especially the stable monitoring and indication of temperature within the normal operating range, and can identify various potential defects in the temperature gauge, preventing the use of unqualified spare parts in the field or introducing hidden dangers into the next operating cycle, greatly improving operational stability.

[0095] See Figure 2 One embodiment of the present invention discloses a calibration device for use in the calibration method of the oil-immersed transformer temperature gauge in any of the above embodiments. The calibration device can at least heat and display the heating temperature, and can assist in the calibration of the oil-immersed transformer temperature gauge.

[0096] In some embodiments, the calibration device includes a housing 1, an oil storage and heating tank 2, a thermometer 3, a temperature display 4, and a heating module 5; the oil storage and heating tank 2 and the heating module 5 are disposed within the housing 1; the heating module 5 is connected to the oil storage and heating tank 2 to heat the oil storage and heating tank 2; the thermometer 3 is disposed inside the oil storage and heating tank 2 to detect the internal temperature of the oil storage and heating tank 2; the temperature display 4 is connected to the thermometer 3 to display the temperature value of the thermometer 3 in real time. Figure 3 As shown, in actual use, the probe 6 of the temperature gauge is placed in the oil storage heating tank 2, and the heating module 5 is used for heating. The temperature value on the temperature display 4 is compared with the data displayed on the dial 7 of the temperature gauge.

[0097] Referring to Tables 1 to 4, this is an embodiment of the temperature gauge performance testing using the calibration method and apparatus for oil-immersed transformer temperature gauges of the present invention. Three temperature gauges are calibrated. Tables 1 to 3 show the selected temperature calibration points and calibration data for the three temperature gauges, respectively. Table 4 shows the calibration data for the ambient temperature compensation adjustment function of the temperature gauges. Note that slashes in the tables indicate items that are not applicable or not present.

[0098] As can be seen from Tables 1 to 3, the temperature calibration points of Thermometer 1 and Thermometer 2 are qualified and do not require calibration. The calibration data of the temperature calibration points of Thermometer 3 show a positive deviation, and it is qualified after calibration. Specifically, for the case where all the deviations of Thermometer 3 are positive, (the maximum deviation value - the minimum deviation value) / 2 is the standard value. The pointer of the thermometer is adjusted downward by this standard value as a whole, that is, [(63.8 - 60) - (96.6 - 96)] / 2 = 1.6, and the pointer is adjusted downward by the value of 1.6. Then Thermometer 3 is recalibrated at the original temperature calibration points. As a result, the maximum deviation value is 1.8 °C ≤ 2 °C, and the calibration work of Thermometer 3 is completed and the thermometer is determined to be qualified. Through

[0099] As can be seen from Table 4, the overall horizontal performance of its three thermometers is qualified and can be used in oil-immersed transformers.

[0100]

[0101] Table 1

[0102]

[0103] Table 2

[0104]

[0105] Table 3

[0106]

[0107] Table 4

[0108] By implementing the present invention, the following beneficial effects are achieved:

[0109] The calibration method of the oil-immersed transformer thermometer of the present invention selects temperature calibration points in the actual operation range of the thermometer and considers the influence of ambient temperature changes on the stability of the thermometer, and comprehensively calibrates the single-point temperature calibration and environmental influence functions of the thermometer, which can identify various potential problems of the thermometer in advance and correct them in time, greatly improving the operation stability of the thermometer and thus ensuring the operation stability of the oil-immersed transformer. <00,00272>

[0110] It can be understood that the above embodiments only represent the preferred embodiments of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention; it should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, the above embodiments or technical features can be freely combined, and several deformations and improvements can also be made, which all belong to the protection scope of the present invention, that is, the embodiments described in "in some embodiments" can be freely combined with any of the above and below embodiments; therefore, all equivalent transformations and modifications made to the scope of the claims of the present invention shall fall within the scope covered by the claims of the present invention.

Claims

1. A method for calibrating a temperature gauge for an oil-immersed transformer, characterized in that, Includes the following steps: S100: Temperature calibration point selection: Select several temperature calibration points within the actual operating range of the temperature gauge and between the actual operating maximum value and the maximum value displayed on the temperature gauge dial. S200: Temperature calibration point calibration: A heating test is performed using a calibration device. Temperature change simulation test is performed on each of the individual temperature calibration points, and the dial display value X1 of the temperature gauge and the temperature display value Y1 of the calibration device are observed for each individual temperature calibration point. If X1-Y1 of any temperature verification point is equal to (-1~1)℃, then all temperature verification points are qualified and proceed to the next step; if X1-Y1 of a single temperature verification point is not equal to (-1~1)℃, then the temperature verification point is unqualified and is returned to the factory; if X1-Y1 of at least two temperature verification points is not equal to (-1~1)℃, and X1-Y1 of at least two temperature verification points is less than -1℃ or greater than 1℃, then the temperature is calibrated by adjusting the pointer knob of the thermometer and proceed to the next step. S300: Verification of the ambient temperature compensation adjustment function of the thermometer: Use a heating ribbon to wrap around the tubing of the thermometer to conduct a heating simulation ambient temperature test. Perform ambient temperature change simulation tests on at least 3 of the temperature verification points respectively, and observe the dial display value X2 of the thermometer and the display value Y2 of the verification device at each of the individual temperature verification points. At the same time, check the pointer condition of the thermometer. If X2-Y2 = (-1~1)℃ at any of the temperature calibration points, and the pointer of the thermometer does not jitter or does not jitter after calibration, then the ambient temperature compensation adjustment function of the thermometer is qualified; if X2-Y2 ≠ (-1~1)℃ at any of the temperature calibration points, or if the pointer still jitters after calibration, then the ambient temperature compensation adjustment function of the thermometer is unqualified and it should be returned to the factory.

2. The calibration method for the temperature gauge of an oil-immersed transformer according to claim 1, characterized in that, S100 includes the following sub-steps: S110: Read the dial data of the temperature gauge and define the maximum value displayed on the dial as temperature point t1; S120: Retrieve the operating history of the temperature gauge described above, and take the highest operating temperature within the past 5 years as temperature point t2; S130: Select several temperature verification points at equal intervals within the range of 0 to t2, and select the first temperature verification point at equal intervals outside the range of t2; S140: Select at least 3 temperature verification points within the range of t2~t1, including t2, t1-10℃ and (t1-10℃+t2).

3. The calibration method for the temperature gauge of an oil-immersed transformer according to claim 2, characterized in that, In step S130, t1 / 10℃ is rounded to the nearest m, with intervals of 2m; the values ​​of several temperature verification points are 2m, 4m, 6m, ... 2m; of which 2m>t2.

4. The calibration method for the temperature gauge of an oil-immersed transformer according to claim 1, characterized in that, S200 includes the following sub-steps: S210: Remove the probe of the temperature gauge and place the probe into the calibration device; S220: Heat the calibration device until its temperature display value matches any of the temperature calibration points, then stop heating; S230: Close the calibration device to maintain the temperature, and after a certain period of time, record the dial display value X1 of the temperature gauge and the temperature display value Y1 of the calibration device; S240: Repeat steps S220 and S230 multiple times until all the temperature verification points have been experienced once, then stop repeating. S250: Calculate and compare the results of X1-Y1 at each of the temperature verification points; If X1-Y1 = (-1~1)℃ at any of the temperature verification points, then all the temperature verification points are qualified and proceed to the next step; if X1-Y1 ≠ (-1~1)℃ at a single temperature verification point, or if X1-Y1 ≠ (-1~1)℃ at at least two temperature verification points and the result of X1-Y1 includes both positive and negative numbers, then the temperature verification point is unqualified and is returned to the factory; if X1-Y1 ≠ (-1~1)℃ at at least two temperature verification points and the result of X1-Y1 is either positive or negative, then the pointer is corrected by adjusting the pointer knob and proceed to the next step.

5. The calibration method for the temperature gauge of an oil-immersed transformer according to claim 4, characterized in that, In step S250, if it is found that X1-Y1 ≠ (-1~1)℃ at a single temperature verification point, the verification device is heated again until its temperature display value is consistent with that single temperature verification point, and then the heating is stopped; steps S230 and S250 are repeated.

6. The calibration method for the temperature gauge of an oil-immersed transformer according to claim 4, characterized in that, In step S250, if X1-Y1≠(-1~1)℃ at at least two of the temperature calibration points and the result of X1-Y1 is negative or positive, then half of the result of the maximum deviation value minus the minimum deviation value is taken as the standard value, and the temperature gauge pointer is adjusted upward or downward to the standard value; repeat S200 to verify the correction effect; If the maximum deviation is ≤2℃ after repeating S200, the temperature gauge calibration is complete.

7. The calibration method for the temperature gauge of an oil-immersed transformer according to claim 1, characterized in that, S300 includes the following sub-steps: S310: Verify the ambient temperature compensation adjustment function of the pipeline between the probe and the head of the thermometer; use the heating ribbon to unevenly wrap around the entire pipeline, use the verification device to heat to any of the temperature verification points and heat the heating ribbon, observe the display value X21 of the thermometer dial and the temperature display value Y21 of the heating verification device, and check the pointer of the thermometer at the same time. If X21-Y21=(-1~1)℃ and the pointer does not jitter, then the ambient temperature compensation and adjustment function of the pipeline is qualified and the next step can be carried out. If X21-Y21≠(-1~1)℃, then the ambient temperature compensation and adjustment function of the pipeline is unqualified and it needs to be returned to the factory; if the pointer jitters, then proceed to the next step after correcting the pointer. S320: Verify the ambient temperature compensation adjustment function of the pipeline near the probe between the probe and the meter head of the thermometer; wrap the heating ribbon around the pipeline near the probe, use the verification device to heat to any of the temperature verification points and heat the heating ribbon, observe the dial display value X22 of the thermometer and the temperature display value Y22 of the verification device, and check the pointer of the thermometer at the same time. If X22-Y22=(-1~1)℃ and the pointer does not jitter, then the ambient temperature compensation adjustment function of the pipeline near the probe is qualified and the next step can be performed. If X22-Y22≠(-1~1)℃, the ambient temperature compensation adjustment function of the pipeline near the probe is unqualified and it should be returned to the factory; if the pointer jitters, the next step is carried out after the pointer is calibrated. S330: Verify the ambient temperature compensation adjustment function of the pipeline between the probe and the meter head of the thermometer near the meter head; wrap the heating ribbon around the pipeline near the meter head, use the verification device to heat to any of the temperature verification points and heat the heating ribbon, observe the display value X23 of the thermometer dial and the display value Y23 of the verification device, and check the pointer of the thermometer at the same time. If X23-Y23=(-1~1)℃ and the pointer does not jitter, then the ambient temperature compensation adjustment function of the pipeline near the meter head is qualified; if X23-Y23≠(-1~1)℃ or the pointer jitters, then the ambient temperature compensation adjustment function of the thermometer is unqualified and it should be returned to the factory.

8. The calibration method for the temperature gauge of an oil-immersed transformer according to any one of claims 1-7, characterized in that, The calibration method for the temperature gauge of the oil-immersed transformer also includes the following steps: S400: Horizontal overall performance verification of multiple temperature gauges on the same device; heating test using the verification device and heating simulation ambient temperature test by wrapping the pipeline with the heating ribbon, while performing temperature change simulation test on multiple temperature gauges, observing the dial display value X3 of multiple temperature gauges respectively, and checking the pointer condition of the temperature gauges. If, under the same heating temperature, the dial display value X3 of the multiple temperature gauges is X3 max -X3 min If the temperature is ≤2℃ and the pointer does not jitter, then the overall lateral performance test of the multiple temperature gauges is qualified; if, under the same heating temperature, the dial display value of the multiple temperature gauges is X3 out of X3... max -X3 min If the temperature exceeds 2°C or the pointer fluctuates, multiple temperature gauges need to be calibrated and the overall performance test of multiple temperature gauges on the same device should be repeated.

9. The calibration method for the temperature gauge of an oil-immersed transformer according to claim 8, characterized in that, S400 includes the following sub-steps: S410: Place the probes of multiple temperature gauges in the same calibration device; S420: Start the calibration device and heat it to a random temperature value. After the temperature display value of the calibration device stabilizes, read the dial display value X31 of the temperature gauge and observe the magnitude of the dial display value X31 of each temperature gauge. S430: Repeat step S420 multiple times; If, under the same heating temperature, the dial display value X31 of multiple temperature gauges is X31 max -X31 min If the temperature is ≤2℃, proceed to the next step; if the displayed value X31 of the dials of multiple temperature gauges is ≤2℃ under the same heating temperature, then proceed to the next step. max -X31 min If the temperature is >2℃, then after calibrating the multiple temperature gauges, repeat step S420; S440: Use heating ribbons to wrap around the same position of multiple thermometers, heat the heating ribbons, read the dial display value X32 of multiple thermometers, observe the size of the dial display value X32 of each thermometer and check the pointer jitter of each thermometer. Use heated ribbons to wrap around different positions of multiple thermometers, heat the ribbons, read the dial display value X33 of multiple thermometers, observe the size of the dial display value X33 of each thermometer and check the pointer jitter of each thermometer. If, under the same heating temperature, the dial display value X32 of multiple temperature gauges is X32 max -X32 min ≤2℃ and X33 in X33 max -X33 min If the temperature is ≤2℃ and the pointer of any one of the thermometers does not jitter, then the overall lateral performance test of the multiple thermometers is qualified; if, under the same heating temperature, the dial display value of the multiple thermometers is X32, then X32... max -X32 min >2℃, X33 max -X33 min If the temperature exceeds 2°C or the pointer of any of the aforementioned temperature gauges jitters, then multiple temperature gauges need to be calibrated and the overall lateral performance test of multiple temperature gauges on the same device needs to be repeated.

Images