Digital oil temperature measuring device for transformer

Abstract

The utility model discloses a transformer digital oil temperature measuring device, which comprises a gauge outfit and a PT100 temperature sensor, the gauge outfit comprises a dial plate, a circuit board and a shell, the dial plate is provided with fan-shaped temperature indicating scales, the center of circle is provided with a double-shaft stepping motor, an outer rotating shaft is connected with a real-time temperature pointer, and an inner rotating shaft is connected with a temperature maximum value pointer; the PT100 temperature sensor is pre-buried on the oil surface in the transformer; the circuit board is provided with a processor, a pointer zeroing detection module, a 4-20mA output module, a data storage module, a communication module, a relay module, a state indicating lamp module, a key control module, an AD conversion module and a power supply module. The processor is connected with a corresponding part, and the AD conversion module is connected with the PT100 temperature sensor; the power module is connected with a corresponding component. The oil surface temperature of the transformer is measured digitally, and the in-situ pointer display temperature is consistent with the remote transmission temperature.

Description

Technical Field

[0001] This utility model relates to the field of digital electronic technology, and in particular to a digital oil temperature measuring device for transformers. Background Technology

[0002] In recent years, with the increasing intelligence of power systems, new requirements have been placed on the digitalization of power equipment. Transformers, as core equipment in power transmission and distribution systems, undertake voltage conversion and energy transformation, requiring real-time and accurate monitoring and protection against temperature changes. Since oil-immersed transformers are often installed outdoors in harsh environments with significant temperature and humidity variations, current methods use expansion-type temperature sensors to drive mechanical pointers for on-site temperature display. This method offers advantages such as intuitive on-site display and adaptability to outdoor conditions. However, it is difficult to achieve remote temperature signal transmission, or the transmitted temperature value may differ from the on-site display, failing to meet digitalization requirements. To achieve the digitalization of traditional expansion-type oil-immersed transformer thermometers, various measures have been implemented.

[0003] One approach is to add a resistance temperature detector (RTD) or thermocouple temperature sensor to the existing expansion temperature sensor, converting the temperature value into an electrical signal and transmitting it remotely to a computer system, thus digitizing the temperature measurement of the oil-immersed transformer. However, this method uses two completely different sensors and measurement principles to sample the oil temperature of the oil-immersed transformer, resulting in a large error between the on-site pointer temperature value and the remotely transmitted temperature value, exceeding ten degrees Celsius, and the two cannot be verified.

[0004] Another approach is to install an angular displacement sensor to measure the rotation angle of the on-site temperature pointer. This displacement angle is then converted into an electrical temperature signal and transmitted to a remote computer system, achieving digitized temperature measurement of the oil-immersed transformer. However, angular displacement sensors consist of one or more sets of fixed and rotating sector-shaped plates. To ensure the sensor's accuracy and sensitivity, and to avoid indirect changes in dielectric constant and plate shape due to environmental temperature and other factors that could adversely affect sensor performance, high requirements are placed on the sensor's materials, manufacturing process, and installation accuracy. This method is only suitable for relatively static production environments and is not suitable for use in the operating environment of oil-immersed transformers.

[0005] To adapt to the digital development trend of the power industry, a digital oil temperature measurement device for transformers is proposed. Utility Model Content

[0006] In view of this, the purpose of this utility model is to propose a digital oil temperature measuring device for transformers, which uses digital electronic technology to measure the oil surface temperature of oil-immersed transformers, so that the temperature value displayed by the local pointer is completely consistent with the temperature value transmitted remotely, thus solving the pain point of the original temperature measurement method and meeting the new requirements of digitalization.

[0007] To achieve the aforementioned technical objectives, the present invention employs the following technical solution: a digital oil temperature measuring device for transformers, comprising: a meter head and a PT100 temperature sensor. The meter head includes a dial for displaying temperature, a circuit board, and a housing. The dial and circuit board are installed inside the housing. A fan-shaped temperature indication scale is provided on the upper surface of the dial, and the fan-shaped temperature indication scale is exposed. A dual-axis stepper motor is provided at the center of the fan-shaped temperature indication scale. One side of the dual-axis stepper motor has an inner rotating shaft and an outer rotating shaft coaxially mounted. A real-time temperature pointer is connected to the outer rotating shaft, which drives the real-time temperature pointer to rotate. A maximum temperature pointer is connected to the inner rotating shaft, which drives the maximum temperature pointer to rotate. The PT100 temperature sensor is embedded in the oil surface inside the transformer.

[0008] The circuit board is equipped with a processor, a pointer zero-return detection module, a 4-20mA output module, a data storage module, a communication module, a relay module, a status indicator module, a button control module, an AD conversion module, and a power supply module. The processor is connected to the pointer zero-return detection module, the 4-20mA output module, the data storage module, the communication module, the relay module, the status indicator module, the button control module, the AD conversion module, and the dual-axis stepper motor. The AD conversion module is connected to a PT100 temperature sensor. The power supply module is connected to the relay module, the communication module, the dual-axis stepper motor, the processor, and the AD conversion module.

[0009] Furthermore, the housing includes an upper shell and a lower shell that overlap each other. The upper surface of the upper shell is provided with a circular opening that matches the fan-shaped temperature indicator scale. The circular opening is located on the fan-shaped temperature indicator scale, so that the fan-shaped temperature indicator scale is exposed through the circular opening. The radius of the circular opening is not less than the radius of the fan-shaped area enclosed by the fan-shaped temperature indicator scale.

[0010] Furthermore, the communication module includes two digital RS485 serial communication interfaces, one of which is used for remote communication, and the other is connected to a handheld smart terminal.

[0011] Furthermore, the PT100 temperature sensor is a resistance temperature sensor or a thermocouple temperature sensor.

[0012] Furthermore, the circuit board is also equipped with a PT100 three-wire bridge circuit, which is connected between the AD conversion module and the PT100 temperature sensor; it also includes a backup temperature sensor, which is connected to the PT100 three-wire bridge circuit, and the backup temperature sensor and the PT100 temperature sensor are switched by a processor.

[0013] Furthermore, the PT100 temperature sensor and the backup temperature sensor are respectively connected to the PT100 three-wire bridge circuit by sensing cables, and the sensing cables are detachably connected to the meter head.

[0014] Furthermore, temperature values ​​are evenly distributed on the fan-shaped temperature indicator scale.

[0015] Furthermore, the real-time temperature pointer and the maximum temperature pointer are filled with phosphor.

[0016] Furthermore, the circuit board is also equipped with an address DIP switch, an infrared communication interface, and a current transformer, all of which are connected to the processor.

[0017] Furthermore, the data storage module uses an AT45DB161E flash memory; the power supply module includes a DC-DC step-down circuit and an LDO voltage regulator circuit, the DC-DC step-down circuit is connected to the LDO voltage regulator circuit and the relay module respectively, and the LDO voltage regulator circuit is connected to the communication module, the dual-axis stepper motor, the processor and the AD conversion module respectively; the dual-axis stepper motor is model RY28-05.

[0018] By adopting the above technical solution, the beneficial effects of this utility model compared with the prior art are as follows:

[0019] 1. A dual-pointer temperature display is employed. A dual-axis stepper motor drives both the real-time temperature pointer and the maximum temperature pointer to rotate, achieving pointer-style temperature display. Each stepper motor has a step angle of 1 / 12 degree. When the temperature pointer rotation angle varies from 0 to 240 degrees, corresponding to a temperature measurement range of 0℃ to 160℃, the measurement resolution is less than 0.1℃, achieving high-precision pointer temperature indication. This significantly improves measurement accuracy compared to existing products.

[0020] 2. By employing a PT100 temperature sensor to detect temperature changes, while retaining the original local pointer-style temperature display feature, the PT100 temperature sensor detects temperature changes and transmits the temperature values ​​to the processor for processing. On one hand, it drives a dual-axis stepper motor to achieve pointer-style temperature display; on the other hand, it achieves remote transmission of temperature signals through analog and digital remote transmission functions. Whether local or remote, the same temperature value is used, thus ensuring the consistency of temperature between the local pointer temperature indication and the remote temperature display, completely solving the current market pain point problem.

[0021] 3. The temperature measuring device uses a data storage module that can save historical temperature values. It allows for on-site querying of setting parameters and historical temperatures, facilitating maintenance and filling a gap in current mechanical products in this regard.

[0022] 4. The communication module of the temperature measuring device adopts two digital RS485 serial communication interfaces. One of the digital RS485 serial communication interfaces is used for remote communication, i.e., communication with a remote integrated application host, with internal isolation to improve anti-interference capabilities. The other digital RS485 serial communication interface connects to a handheld smart terminal, reserved for on-site debugging, setting, and upgrades. The digital RS485 serial communication interface can realize parameter setting and calibration. In addition to parameter setting and calibration, it also allows for the reading of the internal parameters and historical data of the temperature measuring device on-site without affecting the normal operation of the device.

[0023] 5. This utility model adopts a PT100 temperature sensor and a backup temperature sensor. The backup temperature sensor and the PT100 temperature sensor are switched through a processor, making it easier to replace the PT100 temperature sensor. On-site sensor replacement does not require power outages and does not affect transformer operation, which facilitates the use and maintenance of the temperature measuring device.

[0024] 6. On-site parameter settings and calibrations can be achieved through panel operation without opening the cover or powering off, thus not affecting transformer operation and facilitating the use and maintenance of the temperature measuring device.

[0025] 7. The temperature measuring device directly samples the current through a current transformer and uses intelligent microelectronic circuitry to achieve temperature rise compensation for the windings, eliminating the need for a composite transmitter and enabling temperature measurement of oil-immersed transformer windings. This significantly simplifies existing methods for measuring the temperature of oil-immersed transformer windings and improves measurement accuracy. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is an overall structural diagram of a digital oil temperature measuring device for transformers provided by this utility model.

[0028] Figure 2 This is a diagram showing the state of the meter head when the housing is opened, as provided by this utility model.

[0029] Figure 3 This is a schematic diagram of the front structure of the circuit board provided by this utility model.

[0030] Figure 4 This is a schematic diagram of the back structure of the circuit board provided by this utility model.

[0031] Figure 5 This is a schematic diagram of the structure of the dual-axis stepper motor provided by this utility model.

[0032] Figure 6 This is a schematic diagram of the back of the dial and the front of the circuit board provided by this utility model.

[0033] Figure 7 This is a schematic diagram of the front structure of the dial provided by this utility model.

[0034] Figure 8 This is a schematic diagram of the structure of the real-time temperature pointer and the maximum temperature pointer provided by this utility model.

[0035] Figure 9 This is a schematic diagram of the connection structure of the dual-axis stepper motor, real-time temperature pointer, and maximum temperature pointer provided by this utility model.

[0036] Figure 10 This is a schematic diagram of the processor and its corresponding connection provided by this utility model.

[0037] Figure 11 This is a connection diagram of the power module provided by this utility model.

[0038] Explanation of the labels in the diagram:

[0039] 10. Meter Head; 20. PT100 Temperature Sensor; 101. Dial; 102. Circuit Board; 103. Housing; 104. Sector-Shaped Temperature Indicator Scale; 100. Dual-Axis Stepper Motor; 105. Outer Rotating Shaft; 106. Inner Rotating Shaft; 107. Real-Time Temperature Pointer; 1071. Lower Fixing Cap; 1072. Second Pointer; 1073. Outer Sleeve; 1074. Through Hole; 108. Maximum Temperature Pointer; 1081. Upper Fixing Cap; 1082. First Pointer; 1083. Inner Sleeve; 109. Processor; 110. Pointer Zeroing Detection Module; 111. 4- 112. 20mA output module; 113. Data storage module; 114. Communication module; 115. Relay module; 116. Status indicator module; 117. Button control module; 118. AD conversion module; 119. Power supply module; 120. Upper shell; 121. Lower shell; 122. Circular opening; 123. PT100 three-wire bridge circuit; 124. Spare temperature sensor; 125. Sensing cable; 126. Address DIP switch; 127. Infrared communication interface; 128. Current transformer; 129. DC-DC step-down circuit; 120. LDO voltage regulator circuit. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are only for illustrating the present invention and do not limit the scope of the present invention. Similarly, the following embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0041] Please see Figures 1-11 This utility model discloses a digital oil temperature measuring device for transformers, comprising: a meter head 10 and a PT100 temperature sensor 20. The meter head 10 includes a dial 101 for displaying temperature, a circuit board 102, and a housing 103. The dial 101 and the circuit board 102 are installed inside the housing 103. A fan-shaped temperature indication scale 104 is provided on the upper surface of the dial 101. The fan-shaped temperature indication scale 104 is exposed. A dual-axis stepper motor 100 is provided at the center of the fan-shaped temperature indication scale 104. One side of the dual-axis stepper motor 100 has an inner rotating shaft 106 and an outer rotating shaft 105 (e.g., coaxially mounted inner and outer) on one side. Figure 5As shown, the dual-axis stepper motor 100 includes a housing, in which a motor body and a built-in gear transmission system are installed. The gear transmission system is used to drive the outer rotating shaft 105 and the inner rotating shaft 106 to rotate. The outer rotating shaft 105 and the inner rotating shaft 106 are coaxially fitted inside and outside the upper end of the housing. The inner rotating shaft 106 is fitted inside the outer rotating shaft 105, so that the outer rotating shaft 105 and the inner rotating shaft 106 can rotate independently. This allows the real-time temperature pointer 107 and the maximum temperature pointer 108 to rotate independently with the outer rotating shaft 105 and the inner rotating shaft 106, respectively. The dual-axis stepper motor 100 is typically selected from the RY series stepper motors of Dongguan Ruiyi Automotive Electronics Technology Co., Ltd. The specific model of the dual-axis stepper motor 100 (instrument dual-axis stepper motor) can be RY28-05. The RY29 series stepper motor is specifically designed for driving the indicating elements (such as pointers) of vehicle instruments and other precision indicating devices. This motor can directly accept digital signals from the system, drive and fix the pointer at a certain position to indicate the required parameters. A real-time temperature pointer 107 is connected to the outer rotating shaft 105, and the real-time temperature pointer 107 is rotated by the outer rotating shaft 105. A maximum temperature pointer 108 is connected to the inner rotating shaft 106, and the maximum temperature pointer 108 is rotated by the inner rotating shaft 106. The PT100 temperature sensor 20 is embedded in the oil surface inside the transformer for monitoring the internal oil temperature.

[0042] The real-time temperature pointer 107 and the maximum temperature pointer 108 are a dual-pointer structure, specifically:

[0043] The maximum temperature pointer 108 includes an upper fixed cap 1081, a first pointer 1082, and an inner sleeve 1083. The first pointer 1082 is fixed to the side end of the upper fixed cap 1081, and the inner sleeve 1083 is installed at the bottom center of the upper fixed cap 1081. The real-time temperature pointer 107 includes a lower fixed cap 1071, a second pointer 1072, and an outer sleeve 1073. The second pointer 1072 is fixed to the side end of the lower fixed cap 1071, and the outer sleeve 1073 is installed at the bottom center of the lower fixed cap 1071. A through hole 1074 is formed at the center of the upper surface of the lower fixed cap 1071. The inner sleeve 1083 passes through the through hole 1074 and the outer sleeve 1073 and is fitted onto the inner rotating shaft 106. The outer sleeve 1073 is fitted onto the outer rotating shaft 105.

[0044] The circuit board 102 is equipped with a processor 109, a pointer zero-return detection module 110, a 4-20mA output module 111, a data storage module 112, a communication module 113, a relay module 114, a status indicator module 115, a button control module 116, an AD conversion module 117, and a power supply module 118. The processor 109 is connected to the pointer zero-return detection module 110, the 4-20mA output module 111, the data storage module 112, the communication module 113, the relay module 114, the status indicator module 115, the button control module 116, the AD conversion module 117, and the dual-axis stepper motor 100. The AD conversion module 117 is connected to the PT100 temperature sensor 20. The power supply module 118 is connected to the relay module 114, the communication module 113, the dual-axis stepper motor 100, the processor 109, and the AD conversion module 117.

[0045] The expansion-type temperature sensor is replaced by an electronic PT100 temperature sensor 20. A dual-axis stepper motor 100 drives the real-time temperature pointer 107 and the maximum temperature pointer 108 to rotate, achieving pointer-style temperature display. A communication module 113 enables remote transmission of digital temperature signals. While retaining the original local pointer-style temperature display feature, the PT100 temperature sensor 20 detects temperature changes and transmits the temperature values ​​to the processor 109 for processing. This drives the dual-axis stepper motor 100 to achieve pointer-style temperature display, and simultaneously transmits the temperature signal remotely via analog and digital transmission functions. The same temperature value is used for both local and remote transmission, ensuring consistency between the local pointer temperature indication and the remote temperature display. Because the temperature measuring device adopts the latest microelectronic technology and optimizes its internal and external structure, it achieves intelligent and digital operation while also possessing high anti-interference capabilities, high and low temperature resistance, and high protection against humidity and dust, meeting the outdoor environmental requirements of oil-immersed transformer thermometers.

[0046] In this embodiment, the inner rotating shaft 106 and the outer rotating shaft 105 of the dual-axis stepper motor 100 are arranged coaxially with inner and outer sleeves. Their shaft diameters are different, and the outer rotating shaft 105 and the inner rotating shaft 106 are independently configured and will not interfere with each other during rotation. A real-time temperature pointer 107 is connected to the outer rotating shaft 105, which drives the real-time temperature pointer 107 to rotate, pointing to the corresponding scale position on the fan-shaped temperature indication scale 104. A maximum temperature pointer 108 is connected to the inner rotating shaft 106, which drives the maximum temperature pointer 108 to rotate, pointing to the scale position corresponding to the historical maximum temperature on the fan-shaped temperature indication scale 104. A dual-pointer, dual-axis stepper motor is used to replace the traditional mechanical pointer, realizing temperature indication and maximum value indication on the dial 101. The real-time temperature pointer 107 provides real-time temperature indication, and the maximum temperature pointer 108 provides historical maximum temperature indication.

[0047] In this embodiment, the housing 103 includes an upper shell 119 and a lower shell 120 that overlap each other. The upper surface of the upper shell 119 is provided with a circular opening 121 that matches the fan-shaped temperature indicator scale 104. The circular opening 121 is located on the fan-shaped temperature indicator scale 104, so that the fan-shaped temperature indicator scale 104 is exposed through the circular opening 121. The radius of the circular opening 121 is not less than the radius of the fan-shaped area enclosed by the fan-shaped temperature indicator scale 104, ensuring that the scale value of the fan-shaped temperature indicator scale 104 can be completely exposed.

[0048] In this embodiment, the communication module 113 includes two digital RS485 serial communication interfaces. One of these interfaces enables remote communication, i.e., communication with a remote integrated application host, with internal isolation to improve anti-interference capabilities. The other interface connects to a handheld smart terminal, reserved for on-site debugging, setup, and upgrades. The digital RS485 serial communication interface allows for parameter setting and calibration. Besides parameter setting and calibration, it also allows for on-site reading of the temperature measuring device's internal parameters and historical data without affecting the device's normal operation.

[0049] In this embodiment, the PT100 temperature sensor 20 is a resistance temperature sensor or a thermocouple temperature sensor.

[0050] In this embodiment, the circuit board 102 is further provided with a PT100 three-wire bridge circuit 122, which is connected between the AD conversion module 117 and the PT100 temperature sensor 20. It also includes a backup temperature sensor 123, which is connected to the PT100 three-wire bridge circuit 122. Switching between the backup temperature sensor 123 and the PT100 temperature sensor 20 is achieved through the processor 109. The PT100 three-wire bridge circuit 122 is used to eliminate errors. By adjusting the value of the reference resistor, the bridge is balanced, making the voltage signal output by the bridge proportional to the temperature. This allows the output voltage signal to be used to measure the temperature and eliminate errors.

[0051] In this embodiment, the PT100 temperature sensor 20 and the backup temperature sensor 123 are connected to the PT100 three-wire bridge circuit 122 by a sensing cable 124. The sensing cable 124 is detachably connected to the meter 10. The replacement of the PT100 temperature sensor 20 is more convenient. On-site sensor replacement does not require power outage and does not affect the operation of the transformer, which facilitates the use and maintenance of the temperature measuring device.

[0052] In this embodiment, temperature values ​​are uniformly distributed on the fan-shaped temperature indicator scale. The temperature values ​​of the fan-shaped temperature indicator scale 104 are set to 0° to T°, and T° ranges from 150° to 180°. There are n evenly distributed grids, so the temperature of each grid is w = T° / n, and w ranges from 1° to 2°. When the real-time temperature pointer 107 rotates from 0° to T°, the corresponding angle range is 0 to a, and the angle a ranges from 240° to 270°. The corresponding angle that needs to be pushed for every 1° is a / T°. The step angle value of the dual-axis stepper motor 100 is set to m according to a / T°, ensuring that a / T° - 0.1 < m * p ≤ a / T°. Wherein, T, n, w, a, and p are all positive integers.

[0053] For example, when the temperature value of the fan-shaped temperature indicator scale 104 is 0° to 160° and is evenly divided into 160 divisions, the temperature of each division is 1°. When the temperature pointer rotates within the range of 0-240 degrees, the corresponding angle that needs to be pushed for each division is 1.5 degrees. The step angle of the dual-axis stepper motor 100 is 1 / 12 degree for each push, and it needs to be pushed 18 times to reach 1.5 degrees, that is, 1 / 12 degree * 18 = 1.5 degrees. At this time, the accuracy is very high.

[0054] When the temperature value of the fan-shaped temperature indicator scale 104 is 0° to 160° and is evenly divided into 80 divisions, the temperature of each division is 2°. When the temperature pointer rotates within the range of 0-240 degrees, each division (2°) requires a corresponding push angle of 3 degrees, and each 1° requires a corresponding push angle of 1.5 degrees. The dual-axis stepper motor 100 pushes in a single step angle of 1 / 12 degree, requiring 18 pushes to reach 1.5 degrees, i.e., 1 / 12 degree * 18 = 1.5 degrees. At this point, the accuracy is very high. When the corresponding temperature measurement range is 0°C-160°C, the measurement resolution is less than 0.1°C, achieving high-precision pointer temperature indication.

[0055] In this embodiment, the real-time temperature pointer 107 and the maximum temperature pointer 108 are filled with fluorescent powder, and fluorescent pointers are used to facilitate temperature observation in dark environments such as basements or at night.

[0056] In this embodiment, the circuit board 102 is also equipped with an address DIP switch 125, an infrared communication interface 126, and a current transformer 127. The address DIP switch 125, the infrared communication interface 126, and the current transformer 127 are all connected to the processor 109. The infrared communication interface 126, through "transmit" and "receive" diodes, can realize parameter setting and calibration. Parameter setting and calibration through the infrared communication interface 126 does not affect the normal operation of the device. The current transformer 127 is used to sample current. Through intelligent microelectronic circuits, it realizes temperature rise compensation for winding temperature measurement, eliminating the need for a composite transmitter and realizing the measurement of oil-immersed transformer winding temperature, greatly simplifying the existing oil-immersed transformer winding temperature measurement method and improving measurement accuracy.

[0057] In this embodiment, the data storage module 112 uses an AT45DB161E flash memory. This module can save historical temperature values, allowing for on-site querying of setting parameters and historical temperatures, facilitating maintenance and filling a gap in current mechanical products. The power supply module 118 includes a DC-DC step-down circuit 128 and an LDO voltage regulator circuit 129. The DC-DC step-down circuit 128 is connected to the LDO voltage regulator circuit 129 and the relay module 114, respectively. The LDO voltage regulator circuit 129 is connected to the communication module 113, the dual-axis stepper motor 100, the processor 109, and the AD conversion module 117, respectively. The dual-axis stepper motor 100 is a model RY28-05, driven by a VID6608 chip.

[0058] The working principle of using a dual-axis stepper motor 100 to achieve pointer-type temperature display is as follows:

[0059] Temperature values ​​are collected by the PT100 temperature sensor 20 and sent to the processor 109. The processor 109 determines the corresponding pulse to be output based on the collected temperature value and the step angle of the dual-axis stepper motor 100, and controls the outer rotating shaft 105 of the dual-axis stepper motor to rotate the corresponding number of divisions through the pulse, so that the real-time temperature pointer 107 rotates to the corresponding temperature.

[0060] The dual-axis stepper motor 100 uses the RY system dual-axis output stepper motor with model number RY28-05. During production, the step angle of the dual-axis stepper motor 100 is 1 / 12 degree by default.

[0061] In this embodiment, the temperature value of the fan-shaped temperature indicator scale 104 is set to 0° to T°, where T° ranges from 150° to 180°; it is evenly distributed with n grids, so the temperature of each grid is w = T° / n, where w ranges from 1° to 2°; the angle range corresponding to the rotation of the real-time temperature pointer 107 from 0° to T° is 0 to a, where angle a ranges from 240° to 270°; the corresponding angle that needs to be pushed for every 1° is a / T°; the step angle value of the dual-axis stepper motor 100 is set to m according to a / T°, ensuring that a / T° - 0.1 < m * p ≤ a / T°; where T, n, w, a, and p are all positive integers.

[0062] For example, when the temperature value of the fan-shaped temperature indicator scale 104 is 0° to 160° and is evenly divided into 160 divisions, the temperature of each division is 1°. When the temperature pointer rotates within the range of 0-240 degrees, the corresponding angle that needs to be pushed for each division is 1.5 degrees. The step angle of the dual-axis stepper motor 100 is 1 / 12 degree for each push, and it needs to be pushed 18 times to reach 1.5 degrees, that is, 1 / 12 degree * 18 = 1.5 degrees. At this time, the accuracy is very high.

[0063] When the temperature value of the fan-shaped temperature indicator scale 104 is 0° to 160° and is evenly divided into 80 divisions, the temperature of each division is 2°. When the temperature pointer rotates within the range of 0-240 degrees, each division (2°) requires a corresponding push angle of 3 degrees, and each 1° requires a corresponding push angle of 1.5 degrees. The dual-axis stepper motor 100 pushes in a single step angle of 1 / 12 degree, requiring 18 pushes to reach 1.5 degrees, i.e., 1 / 12 degree * 18 = 1.5 degrees. At this point, the accuracy is very high. When the corresponding temperature measurement range is 0°C-160°C, the measurement resolution is less than 0.1°C, achieving high-precision pointer temperature indication.

[0064] Therefore, based on the preset temperature range of the fan-shaped temperature indicator scale 104, the temperature pointer rotation angle range, and the step angle of a single push of the dual-axis stepper motor 100, it is possible to calculate how many times the outer rotating shaft 105 and inner rotating shaft 106 of the dual-axis stepper motor 100 need to be pushed to reach the temperature of each segment in the fan-shaped temperature indicator scale. Then, the processor 109 calculates the number of times the dual-axis stepper motor 100 needs to be pushed based on the temperature value sent by the PT100 temperature sensor 20, and outputs the corresponding pulse to drive the outer rotating shaft 105 of the dual-axis stepper motor 100 to rotate.

[0065] Specifically, the functions of the different modules are as follows:

[0066] 1. The PT100 temperature sensor 20 is encapsulated in armor for measurement using PT100. Its structural dimensions are consistent with traditional temperature sensors, fully complying with national standards and can directly replace existing temperature sensors for modification and upgrade.

[0067] 2. The data storage module 112 uses onboard flash with a capacity of up to 2M bytes. Based on the data volume of one piece of information stored by the existing thermometer (14 bytes), it can store 100,000 data records, and can also reserve some space for storing product information and software upgrades;

[0068] 3. The communication module 113 has two RS485 outputs. One output communicates with the remote integrated application host, with internal isolation to improve anti-interference capabilities. The other output is reserved for on-site debugging, configuration, and upgrades.

[0069] 4. The relay module 114 has 5 pairs of normally switched contacts (relay switch contacts), corresponding to the output status of 4 temperature alarm values ​​and local faults. When the processor 109 collects the temperature value and finds that it has reached or exceeded a certain set alarm value, it controls the corresponding dry contact to close, and outputs faults such as sensor open circuit or communication abnormality.

[0070] 5. The status indicator module 115 has 6 indicator lights for indicating the status of the instrument on site, including normal operation status, setting status, over-temperature alarm status at the corresponding temperature point, and fault status.

[0071] 6. The button control module 116 has 7 tactile switches corresponding to the setting keys (K1, K2, K3, K4) for 4 temperature values, as well as the confirm, increase, and decrease keys, which are used to set 4 alarm temperature points and reset the highest temperature pointer to zero.

[0072] 7. The meter 10 used for on-site temperature indication adopts a dual-pointer meter 10, which can be controlled by the processor 109 to rotate. The real-time temperature pointer 107 indicates the real-time oil level temperature and the set value when setting the alarm temperature value; the maximum temperature pointer 108 indicates the historical highest temperature. When it needs to be zeroed, pressing and holding the confirm button causes the processor 109 to control the real-time temperature pointer 107 to rotate in the opposite direction, thus causing the maximum temperature pointer 108 to return to zero. The on-site display shows the real-time temperature, with an effective range of 0–160℃; each small division represents 1 degree.

[0073] 8. Set temperature display

[0074] Upon entering the setting state, the processor 109 drives the pointer to the previously stored setting value in memory, at which point the indicator light corresponding to the set temperature point flashes. Adjust the set temperature using the up and down buttons, with increments of 1 / 12 degree. A long press continuously increases or decreases the temperature. When the pointer reaches the desired temperature point, release the button, press the OK button to save and exit the settings. The temperature pointer resumes indicating the current temperature, and the temperature alarm indicator light turns off. When the temperature reaches a set alarm value, the corresponding indicator lights K1 to K4 remain illuminated.

[0075] 9. The pointer homing detection module 110 determines the pointer's position after power failure and restoration, ensuring that it rotates in steps starting from 0, thus guaranteeing the precision and accuracy of the pointer indication.

[0076] 10. The power module 118 adopts a wide-voltage DC-DC step-down circuit 128, with a 12 to 36V input and a fixed 9V output, so that the input voltage meets the requirements of 12V / 24V applications; the 9V is used for relays (a 5V relay draws 80mA, so a 9V relay is more reasonable). The LDO voltage regulator circuit 129 uses a 5V output to supply 485 communication and motor control, and then splits it into two 3.3V outputs, one for powering the analog circuit and the other for powering the processor 109.

[0077] In this embodiment, the relay module 114, the status indicator module 115, and the button control module 116 are specifically as follows:

[0078] The relay module 114 contains 5 pairs of relay switch contacts: "K1", "K2", "K3", "K4" and "ER", enabling the remote transmission of 4 temperature alarm signals, corresponding to 4 temperature settings. When the temperature measuring device malfunctions, the alarm is transmitted remotely via the "ER" contact.

[0079] The status indicator module 115 includes six indicator lights: "Run", "K1", "K2", "K3", "K4" and "ER". It works in conjunction with the dual-axis stepper motor 100, dial 101 (with fan-shaped temperature indicator scale 104), seven buttons, and address DIP switch 125 to set parameters and functions.

[0080] The button control module 116 includes seven buttons: "Confirm," "Increase," "Decrease," "S1," "S2," "S3," and "S4." It works in conjunction with the dual-axis stepper motor 100, dial 101 (with a fan-shaped temperature indicator scale 104), six indicator lights, and address DIP switch 125 to set parameters and functions.

[0081] The temperature measuring device includes three address DIP switches 125. The numbers on the three DIP switches 125 correspond to the hundreds, tens, and units digits of the communication address, respectively. By adjusting the positions of the three DIP switches, the communication address of the temperature measuring device can be set.

[0082] This invention employs an indicator pointer, buttons, and indicator lights to achieve functions such as setting over-temperature alarm values, setting calibration values, setting maximum values ​​to zero, setting communication addresses, and enabling functions, as well as indicating abnormal parameter states. On-site parameter settings and calibrations can be performed via the panel operation.

[0083] 1. Set 4 over-temperature alarm values

[0084] Press the corresponding buttons S1, S2, S3, and S4 for relays K1, K2, K3, and K4. The corresponding indicator lights will flash, indicating that you are entering the corresponding alarm temperature setting state. The pointer will then point to the original alarm temperature setting value. Adjust the temperature setting value using the "Increase" and "Decrease" buttons. Once the pointer reaches the desired temperature value, press the "OK" button to save and exit.

[0085] 2. Set calibration values ​​(compensation, zeroing)

[0086] Press and hold the "OK" button for 3 seconds. The power (run) indicator will flash intermittently twice, indicating the calibration value setting state. The temperature pointer will point to the original temperature compensation value. Adjust the temperature compensation value by pressing the "Increase" and "Decrease" buttons. Each press increments the pointer value by 0.5 degrees, while a long press increases it rapidly. Once the pointer reaches the desired temperature value, press the "OK" button to save and exit.

[0087] 3. Maximum value returns to zero

[0088] Press and hold the "Increase" button for 3 seconds; the power (run) indicator will flash intermittently 4 times. Then, press the "K1," "K2," and "OK" buttons in sequence to confirm and reset the maximum value to zero. If any other button is pressed accidentally, the maximum value will not reset to zero. Once the maximum value is reset, it will point to the current temperature value, which will then be used as the maximum value to restart recording.

[0089] 4. Communication address settings

[0090] In normal operation, press and hold the "Minus" button for more than 3 seconds until the ER indicator light flashes rapidly. At this time, use a screwdriver to adjust the address DIP switch 125 to modify the communication address. The numbers on the three DIP switches correspond to the hundreds, tens, and units digits of the communication address, respectively. After adjusting, delay for 1 second and release the "Minus" button. Address settings are only effective when the ER light is flashing rapidly.

[0091] 5. Function Enable Settings

[0092] After powering on the device, press the "OK" + "Minus" keys simultaneously to enter the system setting state. The power (run) indicator and the ER indicator will flash simultaneously. Press S1, then S2, then S3, and then "OK" to enter the function enable setting state.

[0093] Press the corresponding switch button to turn the corresponding function on or off. S1 enables the PT100 input function, S2 enables the 4-20mA output function, and S3 enables the CT detection function. Press the "OK" button to save and proceed to the next setting; press the "S4" button to proceed to the next setting without saving.

[0094] Pressing the S1 key illuminates LED_K1, enabling the PT100 input and connecting it to the internal amplifier circuit. Pressing the S1 key again turns off LED_K1, disabling the PT100 input function.

[0095] Pressing the S2 button illuminates LED_K2, indicating that the 4-20mA output function is enabled. Pressing the S1 button again turns off LED_K2, disabling the 4-20mA output function.

[0096] Pressing the S3 key illuminates LED_K3, indicating that the current transformer 127 (CT) detection function is enabled, i.e., the winding temperature measurement function is realized. Pressing the S3 key again turns off LED_K3, disabling the current transformer 127 (CT) detection function.

[0097] 6. Abnormal parameter status

[0098] The PT100 parameters are abnormal; the ER indicator light and four switch indicator lights are flashing slowly and continuously.

[0099] CT input parameters are abnormal (only for winding thermometers). The ER indicator light and 3 switch indicator lights flash slowly and continuously.

[0100] The 4-20mA current output parameters are abnormal, and the ER indicator light and two switch indicator lights flash slowly and continuously.

[0101] The above description is only a part of the embodiments of this utility model, and does not limit the scope of protection of this utility model. Any equivalent device or equivalent process transformation made based on the contents of this utility model specification and drawings, or directly or indirectly applied to other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A digital oil temperature measuring device for transformers, characterized in that, include: The meter and PT100 temperature sensor are described. The meter includes a dial for displaying temperature, a circuit board, and a housing. The dial and circuit board are installed inside the housing. The upper surface of the dial has a fan-shaped temperature indication scale, which is exposed. A dual-axis stepper motor is located at the center of the fan-shaped temperature indication scale. Each side of the dual-axis stepper motor has an inner and an outer rotating shaft coaxially mounted. A real-time temperature pointer is connected to the outer rotating shaft, which drives the real-time temperature pointer to rotate. A maximum temperature pointer is connected to the inner rotating shaft, which drives the maximum temperature pointer to rotate. The PT100 temperature sensor is embedded in the oil surface inside the transformer. The circuit board is equipped with a processor, a pointer zero-return detection module, a 4-20mA output module, a data storage module, a communication module, a relay module, a status indicator module, a button control module, an AD conversion module, and a power supply module. The processor is connected to the pointer zero-return detection module, the 4-20mA output module, the data storage module, the communication module, the relay module, the status indicator module, the button control module, the AD conversion module, and the dual-axis stepper motor. The AD conversion module is connected to a PT100 temperature sensor. The power supply module is connected to the relay module, the communication module, the dual-axis stepper motor, the processor, and the AD conversion module.

2. The digital oil temperature measuring device for transformers as described in claim 1, characterized in that, The housing includes an upper shell and a lower shell that overlap each other. The upper surface of the upper shell is provided with a circular opening that matches the fan-shaped temperature indicator scale. The circular opening is located on the fan-shaped temperature indicator scale, so that the fan-shaped temperature indicator scale is exposed through the circular opening. The radius of the circular opening is not less than the radius of the fan-shaped area enclosed by the fan-shaped temperature indicator scale.

3. The digital oil temperature measuring device for transformers as described in claim 1, characterized in that, The communication module includes two digital RS485 serial communication interfaces. One of the digital RS485 serial communication interfaces is used for remote communication, and the other digital RS485 serial communication interface is connected to a handheld smart terminal.

4. The digital oil temperature measuring device for transformers as described in claim 1, characterized in that, The PT100 temperature sensor is either a resistance temperature sensor or a thermocouple temperature sensor.

5. The digital oil temperature measuring device for a transformer as described in claim 4, characterized in that, The circuit board also includes a PT100 three-wire bridge circuit, which is connected between the AD conversion module and the PT100 temperature sensor; it also includes a backup temperature sensor, which is connected to the PT100 three-wire bridge circuit, and the backup temperature sensor and the PT100 temperature sensor are switched by a processor.

6. The digital oil temperature measuring device for transformers as described in claim 5, characterized in that, The PT100 temperature sensor and the backup temperature sensor are connected to the PT100 three-wire bridge circuit via sensing cables, and the sensing cables are detachably connected to the meter head.

7. The digital oil temperature measuring device for transformers as described in claim 1, characterized in that, Temperature values ​​are evenly distributed on the fan-shaped temperature indicator scale.

8. The digital oil temperature measuring device for transformers as described in claim 1, characterized in that, The real-time temperature pointer and the maximum temperature pointer are filled with phosphor.

9. The digital oil temperature measuring device for a transformer as described in claim 1, characterized in that, The circuit board is also equipped with an address DIP switch, an infrared communication interface, and a current transformer, all of which are connected to the processor.

10. The digital oil temperature measuring device for a transformer as described in claim 1, characterized in that, The data storage module uses an AT45DB161E flash memory; the power supply module includes a DC-DC step-down circuit and an LDO voltage regulator circuit. The DC-DC step-down circuit is connected to the LDO voltage regulator circuit and the relay module, respectively. The LDO voltage regulator circuit is connected to the communication module, the dual-axis stepper motor, the processor, and the AD conversion module, respectively. The dual-axis stepper motor is an RY28-05.

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