A device for testing the on-off performance of a thermal relay

Abstract

The utility model discloses a kind of thermal relay on-off performance test devices, and the device includes test box, control box and power supply box.Test box, its inside is provided with: access base, first temperature sensor, heating sheet and refrigeration sheet, for providing heat insulation test environment for the thermal relay of access access base;Control box, its inside is provided with: temperature controller and pilot lamp, wherein, temperature controller and pilot lamp, heating sheet and refrigeration sheet are electrically connected, and communication connection with first temperature sensor, for according to the signal control heating sheet or refrigeration sheet of first temperature sensor, make the temperature in test box change according to preset on-off temperature range, and respond using access base control pilot lamp;Power supply box, for providing power supply and circuit support for test box and control box.The device structure is reasonable, convenient to operate, and the on-off performance of thermal relay can be detected efficiently and accurately on site, suitable for EMU overhaul and maintenance.

Description

Technical Field

[0001] This utility model relates to the technical field of electrical maintenance and testing equipment for high-speed trains, and in particular to a test device for the on / off performance of a thermal insulation relay. Background Technology

[0002] The undercarriage thermal insulation relay is a crucial component of the water supply and sanitation system on high-speed trains. It closes when the ambient temperature is below 5±2.5℃, activating the heating circuit of the undercarriage water tank to prevent freezing; it opens when the ambient temperature is above 10±2.5℃, stopping the water tank heating. Therefore, the on / off function of the undercarriage thermal insulation relay is vital to the convenience of water supply for passengers on high-speed trains. According to the advanced maintenance procedures for CRH2A / 2C / 380A platform high-speed trains, the undercarriage thermal insulation relay must be removed and its on / off performance tested to ensure it meets requirements. On / off performance is defined as the relay's ability to conduct and disconnect within a specified ambient temperature range.

[0003] Currently, the testing of the on / off performance of undercarriage thermal insulation relays on CRH (China Railway High-speed) series EMUs generally involves disassembling the relays and sending them back to the original manufacturer or a third-party organization for testing. This method suffers from problems such as excessively long maintenance cycles, delayed fault feedback, and high outsourcing costs. During on-site maintenance, there is a lack of dedicated testing equipment, and operators typically rely on general-purpose temperature chambers and multimeters for manual testing. This method has low automation, depends entirely on manual operation and visual judgment, makes it difficult to accurately control the temperature critical point, and cannot automatically record the on / off status and temperature response time. The testing efficiency is low, and the results are inconsistent, seriously affecting the accuracy and timeliness of maintenance of key EMU components, and failing to meet the needs for efficient, accurate, and reliable on-site maintenance. Utility Model Content

[0004] In view of the above-mentioned defects or improvement needs of the existing technology, this utility model provides a test device for the on-off performance of thermal insulation relays, so as to solve the technical problem of inconvenience in on-site testing of the on-off performance of thermal insulation relays.

[0005] This utility model provides a testing device for the on / off performance of a thermal insulation relay. The testing device includes a test chamber, a control box, and a power supply box. The test chamber contains an access base, a first temperature sensor, a heating element, and a cooling element, providing a thermal insulation test environment for the thermal insulation relay connected to the access base. The control box contains a temperature controller and an indicator light. The temperature controller is electrically connected to the indicator light, the heating element, and the cooling element, and communicatively connected to the first temperature sensor. It controls the on / off state of the heating element or the cooling element based on the signal from the first temperature sensor, causing the temperature inside the test chamber to change according to a preset on / off temperature range, and controls the indicator light to respond using the access base. The power supply box provides power and circuit support for the test chamber and the control box.

[0006] In one embodiment of this utility model, the indicator light includes: a first indicator light, electrically connected to the access base, for illuminating when the thermal insulation relay is turned on; and a second indicator light, electrically connected to the access base, for illuminating when the thermal insulation relay is turned off.

[0007] In one embodiment of the present invention, the test chamber further includes: at least two cooling plates, at least two heating plates, and at least two access bases.

[0008] In one embodiment of the present invention, the control box further includes: a plurality of indicator lights, which are electrically connected to the access base respectively, wherein one indicator light corresponds to one access base.

[0009] In one embodiment of this utility model, the control box further includes an on / off counter, which is electrically connected to the access base and is used to record the number of times the thermal insulation relay is switched on and off.

[0010] In one embodiment of the present invention, the test chamber further includes a second temperature sensor for verifying whether the temperature inside the test chamber is consistent with the temperature measured by the first temperature sensor.

[0011] In one embodiment of this utility model, there are at least two second temperature sensors.

[0012] In one embodiment of the present invention, the control box further includes: a verification processor, which is communicatively connected to the second temperature sensor and the first temperature sensor, for determining whether the temperature controller is abnormal; and an abnormality indicator, which is communicatively connected to the verification processor, for alarming when the temperature controller is abnormal.

[0013] In one embodiment of this utility model, the test chamber further includes: The circulating fan is electrically connected to the temperature controller in the power supply box and control box to improve the temperature circulation efficiency within the test chamber.

[0014] To achieve the above objectives, this utility model embodiment implements corresponding temperature control based on the on / off temperature range of the thermal insulation relay, providing multiple methods to determine the on / off response of the thermal insulation relay, and thereby determining whether the on / off operation of the thermal insulation relay is normal, thus realizing the detection of the on / off performance of the thermal insulation relay. Simultaneously, to further ensure the reliability of this utility model embodiment, a verification processor and an anomaly indicator are also included in the design, specifically used to detect whether the temperature detection capability of the temperature controller is normal. When the temperature error exceeds a preset error threshold, an alarm message is issued, which can prevent significant losses in actual use.

[0015] In summary, compared with the prior art, the above-described technical solution conceived by this utility model can achieve the following beneficial effects: It can conveniently detect the switching performance of the thermal insulation relay within various temperature ranges, and indicate whether the switching performance of the thermal insulation relay is abnormal in multiple ways. At the same time, by adding a verification processor and an anomaly indicator, it can detect the anomaly of the temperature controller, taking into account both practicality and stability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the internal structure of the test chamber of a thermal insulation relay switching performance testing device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall appearance of a thermal insulation relay on / off performance testing device in one embodiment of this utility model; Figure 3 This is a schematic diagram of a logic principle in one embodiment of the present utility model.

[0017] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 100-test chamber, 110-first temperature sensor, 120-cooling element, 130-heating element, 140-connection base, 150-second temperature sensor, 200-control box, 210-indicator light, 211-first indicator light, 212-second indicator light, 220-temperature controller, 230-on / off counter, 300-power supply box, 400-thermal insulation relay. Detailed Implementation

[0018] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not intended to limit the present utility model. Furthermore, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figure 1 and Figure 2As shown in a specific embodiment of this utility model, the on / off performance testing device for the thermal insulation relay 400 includes: a test chamber 100, a control box 200, and a power supply box 300; wherein, the test chamber 100 is internally equipped with: an access base 140, a first temperature sensor 110, a heating element 130, and a cooling element 120, for providing a thermal insulation test environment for the thermal insulation relay 400 connected to the access base 140; the control box 200 is internally equipped with: a temperature controller 220 and an indicator light 210, wherein the temperature controller 220... The control box 200 is electrically connected to the indicator light 210, heating element 130, and cooling element 120, and communicatively connected to the first temperature sensor 110. It controls the on / off state of the heating element 130 or cooling element 120 based on the signal from the first temperature sensor 110, causing the temperature inside the test chamber 100 to change according to a preset on / off temperature range. The control box 200 also controls the indicator light 210 to respond. The power supply box 300 provides power and circuit support to the test chamber 100 and the control box 200. Specifically, the first temperature sensor 110 detects the temperature inside the test chamber 100 and sends the temperature data to the temperature controller 220 in the control box 200, causing the heating element 130 and cooling element 120 to start or stop according to the preset on / off temperature range.

[0023] Among them, the cooling chip 120 can be a semiconductor cooling structure built with CL-C067 cooling chip, and the heating chip 130 can be an integrated PTC ceramic heater.

[0024] To facilitate convenient testing of the continuity performance of the undercarriage thermal insulation relay 400 on high-speed trains, the size and complexity of the testing equipment need to be appropriately reduced to achieve portability and low energy consumption. Simultaneously, the test chamber 100 is designed as a box using heat-insulating materials, such as polystyrene, to minimize temperature exchange between the interior and exterior. The test chamber 100 has multiple holes for wiring to pass through. Furthermore, observation windows made of transparent heat-insulating material can be provided on the chamber to ensure its internal insulation. Additionally, in the design of this embodiment, not all required heat dissipation, basic circuits, power supplies, and other essential infrastructure for each unit are shown or labeled in the drawings, but this does not mean that such designs are unnecessary.

[0025] The indicator light 210 is used to display the on / off response of the thermal insulation relay 400. Typically, with only one indicator light 210, it illuminates when the thermal insulation relay 400 is on and extinguishes when it is off, thus displaying the on / off response of the thermal insulation relay 400. Further, the indicator light 210 may include a first indicator light 211 and a second indicator light 212. The first indicator light 211 is electrically connected to the access base 140 and illuminates when the thermal insulation relay 400 is on; the second indicator light 212 is electrically connected to the access base 140 and illuminates when the thermal insulation relay 400 is off. By using two different indicator lights 210 to represent the on / off state of the thermal insulation relay 400, abnormal performance of the thermal insulation relay 400 can be more clearly identified.

[0026] The temperature regulation speed of a single set of cooling elements 120 and heating elements 130 is limited. Therefore, to further improve the temperature change efficiency within the test chamber 100, the test chamber 100 also includes at least two cooling elements 120, at least two heating elements 130, and at least two access bases 140. When the temperature controller 220 controls the cooling elements 120 and heating elements 130 to change the temperature, all cooling elements 120 or heating elements 130 operate simultaneously, effectively improving the temperature change speed. Multiple access bases 140 can simultaneously install and connect multiple thermal insulation relays 400, thereby allowing for simultaneous testing of the on / off performance of multiple thermal insulation relays 400.

[0027] Correspondingly, the control box 200 also includes multiple indicator lights 210, each electrically connected to the access base 140, wherein one indicator light 210 corresponds to one access base 140. When multiple access bases 140 are provided in the test chamber 100, multiple indicator lights 210 are correspondingly provided in the control box 200, with each indicator light 210 corresponding to one access base 140. This allows each thermal insulation relay 400 on each base to correspond to one indicator light 210, thereby enabling simultaneous detection of the on / off performance of multiple thermal insulation relays 400. The same principle applies when the indicator lights 210 are divided into a first indicator light 211 and a second indicator light 212, which will not be elaborated further here.

[0028] The normal operating conditions of the thermal insulation relay 400 are as follows: it must be in the conducting state when the ambient temperature is 5℃, with an error range of 5℃±2.5℃. That is, the thermal insulation relay 400 must be conducting when the ambient temperature is between 2.5℃ and 7.5℃ to ensure the normal operation of the train's thermal insulation function within this temperature range. When the ambient temperature is 10℃, the thermal insulation relay 400 must be in the closed state, with an error range of 10℃±2.5℃. That is, the train's thermal insulation function must be closed when the ambient temperature is between 7.5℃ and 12.5℃. It remains closed in other temperature ranges. Therefore, in actual use, the thermal insulation relay 400 on / off performance testing device can be preset with a temperature change curve based on this temperature range. In a preferred embodiment, the temperature change curve is as follows: when the room temperature is above 12.5℃, which is higher than the 10℃±2.5℃ disconnection temperature range of the thermal insulation relay 400, the temperature curve will decrease from room temperature to 2℃, and then increase from 2℃ to 15℃. When the room temperature is below 2.5℃, the temperature curve will rise from room temperature to 15℃ and then drop to 2℃. In other cases, the temperature will be uniformly lowered to 2℃ first, then raised to 15℃, and finally lowered to 2℃ again. Here, 2℃ and 15℃ are examples and do not represent the only possible values. When the room temperature is above 12.5℃, those skilled in the art can choose any temperature value below 5℃ as the minimum temperature value; when the room temperature is below 2.5℃, any temperature value above 10℃ can be chosen as the maximum temperature value to achieve complete coverage of the conduction and disconnection temperature ranges.

[0029] In order to further save energy, in one embodiment of the present invention, switches are installed on the heating element 130 and the cooling element 120 respectively, so that the temperature can be directly adjusted using room temperature. For example, when the temperature is below 2.5℃, the switch of the cooling element 120 can be turned off to directly cool down using room temperature, thereby achieving the purpose of saving energy. The same applies to the heating element 130.

[0030] Specifically, based on the above design, taking a room temperature exceeding 12.5℃ as an example, the actual usage process of the thermal insulation relay 400 switching performance test device is as follows: The thermal insulation relay 400 to be tested is installed in the access base 140. At this time, since the temperature is higher than the disconnection temperature range, the thermal insulation relay 400 will disconnect, and the second indicator light 212 will light up; the temperature controller 220 will turn off the heating element 130 and turn on the cooling element 120, lowering the temperature inside the test chamber 100 to 7.5℃. During the period when the temperature reaches 7.5℃, the thermal insulation relay 400 will remain in the disconnected state, and the second indicator light 212 will remain lit, indicating that the disconnection function of the thermal insulation relay 400 is normal. When the temperature continues to drop to 7.5℃, it begins to enter the conduction temperature range. Since temperature conduction takes time, the insulation relay 400 will not react at this point and will not be considered damaged. The temperature inside the test chamber 100 will continue to decrease to 2.5℃. If the insulation relay 400 conducts during the temperature drop to 2.5℃, it indicates that the insulation relay 400's conduction function is normal. At this time, the second indicator light 212 will turn off, and the first indicator light 211 will illuminate. To ensure that the insulation relay 400 can still disconnect normally when it leaves the conduction temperature range, the temperature needs to be further reduced to 2℃. Due to the temperature conduction speed, the insulation relay 400 will disconnect within a preset time after the temperature leaves 2.5℃. The first indicator light 211 will turn off, and the second indicator light 212 will illuminate, indicating that its disconnection function is normal. The temperature is then further increased to 12.5℃. During the period from 2.5℃ to 7.5℃, the thermal relay 400 will conduct, the second indicator light 212 will be off, and the first indicator light 211 will be on. When the temperature drops below 7.5℃ within a preset time, the thermal relay 400 will disconnect, the second indicator light 212 will be on, and the first indicator light 211 will be off. Then, when the temperature rises to 15℃, the thermal relay 400 will remain disconnected, meaning the second indicator light 212 will be on and the first indicator light 211 will be off. This indicates that the thermal relay 400 under test is functioning normally and can be used normally. If the thermal relay 400 does not respond correctly within the preset time during the above process, it indicates that its switching performance is abnormal.

[0031] When the room temperature is different from the above description, the performance of the thermal insulation relay 400 within the same conduction temperature range and disconnection temperature range is the same as the above process. The performance of the first indicator light 211 and the second indicator light 212 is also the same as the above content, and will not be described in detail here.

[0032] In the above design, the indicator unit determines the on / off state of the thermal insulation relay 400 through the first indicator light 211 and the second indicator light 212. This process requires continuous observation by personnel, resulting in a significant workload. Therefore, if Figure 2 As shown, the control box 200 also includes an on / off counter 230, which is electrically connected to the access base 140 and is used to record the number of times the thermal insulation relay 400 is switched on and off.

[0033] The on / off counter used in this embodiment of the invention can simultaneously record the number of on / off cycles and the specific time. When the room temperature exceeds 12.5℃, the on / off counter 230 will record 4 on / off cycles during the entire cooling and then heating process of the test. When the room temperature is below 2.5℃, the on / off counter 230 will record 4 on / off cycles. In other cases, counting will begin after the temperature drops to 2℃, and the entire process will also record 4 on / off cycles. At this time, no staff need to supervise the entire process, reducing workload. If the number of cycles increases or decreases, it can be directly determined that the on / off performance is abnormal. The counting time can also be used to determine whether the thermal insulation relay 400 completes the correct on / off cycle within the preset time, thereby further determining whether the on / off performance of the thermal insulation relay 400 is normal.

[0034] In addition, to reduce the interference of voltage fluctuations on the on / off count recording of the on / off counter 230, a filter circuit can be appropriately added to the circuit during the test to reduce the interference of voltage fluctuations.

[0035] like Figure 3 As shown, the actual thermal insulation relay 400 is not a conventional relay with a common terminal. Its on / off function is only the on / off function between the two interfaces. Therefore, a second electromagnetic relay is needed to complete the individual control of the first indicator light 211 and the second indicator light 212. The temperature controller 220 can also achieve the on / off selection of the cooling sub-unit or the heating sub-unit by adding the first electromagnetic relay, simplifying the complexity of the temperature controller 220 and thus allowing for the selection of a simpler control hardware device.

[0036] Furthermore, since temperature control is handled entirely by the temperature control unit throughout the entire test, any malfunction in this core component will result in numerous detection errors. Therefore, to avoid this problem, this embodiment incorporates a verification function into the temperature control unit. The test chamber 100 also includes a second temperature sensor 150, used to verify whether the temperature inside the test chamber 100 matches the temperature measured by the first temperature sensor 110. This redundant verification method verifies the performance of the temperature controller 220 and the first temperature sensor 110, ensuring the equipment itself is error-free.

[0037] The second temperature sensor 150 operates independently of the first temperature sensor 110 and independently obtains the temperature within the test chamber 100. The temperature value detected by the first temperature sensor 110 is used as the first temperature value, and the temperature value measured by the second temperature sensor 150 is used as the second temperature value. If the absolute value of the error between the first and second temperature values ​​exceeds a preset error threshold, it is determined that the on / off performance testing device for the thermal insulation relay 400 is malfunctioning and should be repaired. Furthermore, there are at least two second temperature sensors 150. A single second temperature sensor 150 may lead to serious errors due to accidental factors. Therefore, to further ensure the accuracy of temperature detection by the verification subunit, in one embodiment of this invention, there are at least two second temperature sensors 150. The temperature values ​​measured by multiple temperature sensors are used as a first sub-temperature value. The average value of all first sub-temperature values ​​is calculated, and the absolute value of the error between the average value and the second temperature value is compared to determine the malfunction. Meanwhile, in order to avoid the damage of individual second temperature sensors 150 affecting the average value of the final first sub-temperature value, in one embodiment of this utility model, a preset number of the maximum and minimum values ​​among the multiple first sub-temperature values ​​can be removed, and the average value of the remaining first sub-temperature values ​​can be calculated to solve the problem of individual sensor damage affecting the average value.

[0038] The above process can be completed manually, but in one embodiment of the present invention, the control box 200 further includes: a verification processor, which is communicatively connected to the second temperature sensor 150 and the first temperature sensor 110, for determining whether the temperature controller 220 is abnormal; and an abnormality indicator, which is communicatively connected to the verification processor, for alarming when the temperature controller 220 is abnormal.

[0039] By verifying the temperature values ​​measured by the first temperature sensor 110 and the second temperature sensor 150 and judging them against the preset error range, the abnormal judgment process of the thermal insulation relay 400 on / off performance test device can be completed. When an abnormality is detected, the abnormality indicator uses audible, visual, and electrical signals to indicate the abnormality. At the same time, the abnormality indicator can achieve the purpose of abnormal alarm through various means such as audible, visual, and electrical signals. Those skilled in the art can choose an appropriate method to achieve the same purpose.

[0040] Furthermore, in order to enable the temperature inside the test chamber 100 to change rapidly, in one embodiment of this utility model, a circulating fan is set up to accelerate the airflow speed inside the test chamber 100, thereby improving the temperature circulation efficiency inside the test chamber 100.

[0041] Currently, the thermal insulation relays are being used in the Level 4 maintenance and repair work of CRH2A / 2C / 380A platform EMUs at the Wuhan EMU Depot's EMU maintenance workshop, and their application in the field is performing well.

[0042] The application of this achievement has optimized the maintenance process of the undercarriage thermal insulation relay, shortened the maintenance time of CRH2A / 2C / 380A platform EMUs, made the fault feedback of the relay timely and controllable, and saved maintenance costs.

[0043] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A testing device for the on / off performance of a thermal insulation relay, characterized in that, The device includes: The test chamber (100) is equipped with: a base (140), a first temperature sensor (110), a heating element (130), and a cooling element (120). The test chamber is used to provide a heat insulation test environment for the thermal insulation relay (400) connected to the base (140); the base (140) is used to connect the thermal insulation relay to be tested. The control box (200) contains a temperature controller (220) and an indicator light (210). The temperature controller (220) is electrically connected to the indicator light (210), the heating element (130), and the cooling element (120), and is communicatively connected to the first temperature sensor (110). It controls the on / off state of the heating element (130) or the cooling element (120) according to the signal from the first temperature sensor (110), so that the temperature inside the test chamber (100) changes according to a preset on / off temperature range. The indicator light (210) is controlled by the access base (140) to respond. The indicator light (210) includes a first indicator light (211), which is electrically connected to the access base (140) and illuminates when the thermal insulation relay (400) is turned on; and a second indicator light (212), which is electrically connected to the access base (140) and illuminates when the thermal insulation relay (400) is turned off. A power supply box (300) is used to provide power and circuit support for the test chamber (100) and the control box (200).

2. The thermal insulation relay on / off performance testing device according to claim 1, characterized in that, The test chamber (100) also includes: At least two cooling elements (120), at least two heating elements (130), and at least two access bases (140).

3. The thermal insulation relay on / off performance testing device according to claim 2, characterized in that, The control box (200) also includes: Multiple indicator lights (210) are electrically connected to the access base (140), wherein one indicator light (210) corresponds to one access base (140).

4. The thermal insulation relay on / off performance testing device according to claim 1, characterized in that, The control box (200) further includes an on / off counter (230), which is electrically connected to the access base (140) and is used to record the number of times the thermal insulation relay (400) is switched on and off.

5. The thermal insulation relay on / off performance testing device according to claim 1, characterized in that, The test chamber (100) also includes: The second temperature sensor (150) is used to verify whether the temperature inside the test chamber (100) is consistent with the temperature measured by the first temperature sensor (110).

6. The thermal insulation relay on / off performance testing device according to claim 5, characterized in that, There are at least two second temperature sensors (150).

7. The thermal insulation relay on / off performance testing device according to claim 5 or 6, characterized in that, The control box (200) also includes: The verification processor is communicatively connected to the second temperature sensor (150) and the first temperature sensor (110) to determine whether the temperature controller (220) is abnormal based on the temperature output of the second temperature sensor (150) and the first temperature sensor (110); An anomaly indicator, which is communicatively connected to the verification processor, is used to issue an alarm when the temperature controller (220) malfunctions.

8. The thermal insulation relay on / off performance testing device according to claim 1, characterized in that, The test chamber (100) also includes: A circulating fan, electrically connected to a temperature controller (220) in the power supply box (300) and control box (200), is used to improve the temperature circulation efficiency within the test chamber (100).

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