Low-power instrument transformer having temperature compensation function

Abstract

The objective of the present invention is to provide a low-power instrument transformer having a temperature compensation function, in which a circuit whose output is adjusted according to a temperature is added to the inside of a signal converter without additionally implementing the temperature compensation function in a merge unit. The low-power instrument transformer having a temperature compensation function, according to one embodiment of the present invention, may comprise: a detection unit for detecting a voltage of an object to be measured; and a temperature compensation unit for compensating for a change, according to temperature, in voltage information measured by the detection unit, and outputting same to the merge unit.

Description

Low-power instrumentation transformer with temperature compensation function

[0001] The present invention relates to a low-power measuring transformer having a temperature compensation function.

[0002] Currently, instrumentation transformers are being developed in a direction that replaces internal insulation media with eco-friendly materials and reduces their size and power consumption compared to existing devices.

[0003] Among instrument transformers, the low-power passive instrument transformer (LPIT) is attracting attention as a subject of research and development because it has the advantage of being able to operate without the supply of external power energy, and international standardization is underway.

[0004] In the case of voltage transformers (VTs) among low-power measurement transformers, the detection section is mostly configured with a Capacitive Voltage Divide (CVD) structure. The magnitude of the secondary output is determined by the capacitance of the insulating medium between the primary conductor and the secondary section of the voltage transformer; however, since the capacitance of the insulating medium can vary due to the external environment (especially tank temperature), a compensation device is absolutely necessary.

[0005] However, in the case of low-power measurement transformers, it is impossible to directly compare tank temperature measurement values ​​because external power is not supplied, and even if additional temperature sensors are attached, there is a problem that the functional complexity of the merging unit increases because additional firmware with a temperature sensor input circuit and a temperature compensation control function must be implemented in the merging unit (MU) that merges the detection values.

[0006] According to one embodiment of the present invention, a low-power measurement transformer having a temperature compensation function is provided, wherein a circuit that adjusts the output according to temperature is added inside the signal converter without additionally implementing a temperature compensation function in the merging unit.

[0007] To solve the problem of the present invention described above, a low-power measurement transformer having a temperature compensation function according to one embodiment of the present invention may include a detection unit that detects the voltage of a measurement target, and a temperature compensation unit that compensates for changes in the voltage information measured by the detection unit according to temperature and outputs it to a merging unit.

[0008] According to one embodiment of the present invention, system development and maintenance costs can be reduced, and energy consumption can be reduced.

[0009] FIG. 1 is a schematic diagram of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0010] FIG. 2 is a diagram illustrating the concept of a capacitor being formed on a substrate of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0011] FIG. 3 is a diagram illustrating the concept of a temperature compensation section being formed on a printed circuit board of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0012] FIGS. 4a to 4d are drawings illustrating embodiments of a low-power measuring transformer having a temperature compensation function according to an embodiment of the present invention.

[0013] FIGS. 5 and 6 are graphs showing the electrical characteristics of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0014] Hereinafter, preferred embodiments are described in detail with reference to the attached drawings so that a person skilled in the art can easily implement the present invention.

[0015]

[0016] FIG. 1 is a schematic diagram of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0017] Referring to FIG. 1, a low-power measuring transformer (100) having a temperature compensation function according to one embodiment of the present invention includes a detection unit (110) and a temperature compensation unit (120), and may further include a merging unit (130).

[0018] The detection unit (110) can detect the voltage of the measurement target, and the measurement target may be a conductor of a low-power measurement transformer tank.

[0019] The voltage measured by the detection unit (110) can vary according to temperature, and the temperature compensation unit (120) can compensate the measured voltage that varies according to temperature and output it to the merging unit (130).

[0020] The merging unit (130) can integrate the measured result values, convert them into digital form, and transmit them in a pre-set communication protocol format.

[0021]

[0022] The detector (110) may be configured with a Capacitive Voltage Divide (CVD) structure and may include a first capacitor (111) and a second capacitor (112) in an equivalent circuit.

[0023] The first capacitor (111) may have a capacitance according to the distance between the measurement target and the sensor, and the second capacitor (112) may have a capacitance according to the distance between the sensor and ground. In terms of an equivalent circuit, the first capacitor (111) and the second capacitor (112) may be connected in series between the measurement target and ground, and the output voltage of the detection unit (110) may be determined according to the ratio of the capacitance (C1) of the first capacitor (111) and the capacitance (C2) of the second capacitor (112).

[0024] The temperature compensation unit (120) may include a resistance unit (121) and a variable resistance unit (122).

[0025] The resistor (121) may include at least one resistor (121a, 121b) having a preset resistance value, and the variable resistor (122) may have a resistance value that varies according to temperature and compensate for the output voltage value of the detector (110).

[0026] One end of the first resistor (121a) of the resistor section (121) is connected between the first capacitor (111) and the second capacitor (112) of the detector section (110), and the other end of the first resistor (121a) can be connected to one end of the variable resistor section (122), and the second resistor (121b) can be connected between the other end of the variable resistor section (122) and ground.

[0027]

[0028] FIG. 2 is a diagram illustrating the concept of a capacitor being formed on a substrate of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0029] Referring to FIGS. 1 and 2, the second capacitor (112) of the detection unit (110) may be composed of a double-sided printed circuit board, and the thickness of the printed circuit board may be manufactured to a certain value (e.g., 0.8T) or less, and the ratio of the width to the width of the copper foil may be limited to, for example, 100m or less to maintain a constant size of the capacitance.

[0030] The magnitude of the capacitance according to the area and thickness of the printed circuit board described above may be equal to the following Equation 1.

[0031] (Formula 1)

[0032]

[0033] As shown in the formula above, the first capacitance (C1) or the second capacitance (C2) changes depending on the temperature, and the final output of the detection unit (110) decreases as the temperature increases.

[0034] FIG. 3 is a diagram illustrating the concept of a temperature compensation section being formed on a printed circuit board of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0035] Referring to FIGS. 1 and FIGS. 3, the variable resistor (122) of the temperature compensation unit (120), which is connected in parallel with the second capacitor (112), increases its resistance value as the temperature increases, thereby reducing the ratio of the decrease in the output voltage value of the detection unit (110) according to the temperature.

[0036] The variable resistor (122) can be configured as a thin-film temperature variable resistor, and the resistance characteristics according to temperature are determined by the ratio of the resistivity of the thin-film material to the length and cross-sectional area of ​​the material as shown in Equation 2 below. Platinum material can be mainly used because the resistance temperature coefficient according to temperature is linearly constant.

[0037] (Equation 2)

[0038]

[0039] As described above, for example, to match the reference resistance (resistance value at 0°C) of 5000 kΩ, the ratio of the total length to the cross-sectional area of ​​the platinum pattern can be set to 5.096 x 10¹⁰ / m.

[0040] The first resistor (121a) and the second resistor (121b) of the resistance section (121) of the temperature compensation section (120) may also be composed of thin-film resistors, and the first resistor (121a), the variable resistor section (122), and the second resistor (121b) of the temperature compensation section (120) may be connected in series.

[0041] FIGS. 4a to 4d are drawings illustrating embodiments of a low-power measuring transformer having a temperature compensation function according to an embodiment of the present invention.

[0042] The first resistor (121a), variable resistor (122), and second resistor (121b) of the temperature compensation unit (120) can be packaged (P) on the printed circuit board together with the second capacitor (112), FIG. 4a is a top view of the printed circuit board, and FIG. 4b is a bottom view of the printed circuit board.

[0043] The first resistor (121a) can prevent the variable resistor (122) from discharging due to an excessively high voltage. One end of the first resistor (121a) is connected to the input of the temperature compensation unit (120) between the first capacitor (111) and the second capacitor (112), and the other end of the first resistor (121a), which is connected to the variable resistor (122), is connected to the output of the temperature compensation unit (120), so that the voltage between the temperature compensation unit (120) and ground becomes the final output.

[0044] The second resistor (121b) is a resistor used to maintain a constant ratio error, and can maintain a constant output ratio error according to temperature by minimizing the ratio of output change according to temperature.

[0045] Referring to FIG. 4c, the temperature compensation unit (120) is positioned so that it can be placed on the copper foil located on the outer diameter of the printed circuit board when the printed circuit board is rolled into a circle (see FIG. 4d), so that the primary voltage does not affect the transformer (100).

[0046]

[0047] FIGS. 5 and 6 are graphs showing the electrical characteristics of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention.

[0048] Referring to FIG. 5, compared to the conventional method before temperature compensation, it can be seen that the output of a low-power measuring transformer having a temperature compensation function according to one embodiment of the present invention is stable with respect to temperature changes, and referring to FIG. 6, it can be seen that although the phase error changes somewhat, it is within the reference range.

[0049]

[0050] As described above, according to the present invention, the purpose is to reduce system development and maintenance costs by adding a circuit that adjusts the output according to temperature inside the transformer without additionally implementing a temperature compensation function in the merging unit. Furthermore, by using passive circuits from the detection unit to the merging unit, the overall system energy consumption can be reduced. That is, since only passive components are used without any active components within the signal conversion circuit, there is no energy consumption, and because the internal circuit is composed entirely of analog circuits, the problem of information loss due to quantization error can be avoided. Since the detection unit and the temperature compensation circuit are packaged into a single sensor type, the volume of the transformer can be minimized, measurement errors caused by increased resistance due to the temperature sensor wiring distance can be reduced, and system compatibility can be improved as the existing merging unit can be used as is without modification.

[0051]

[0052] The present invention described above is not limited by the aforementioned embodiments and attached drawings, but is limited by the claims set forth below, and it is readily apparent to those skilled in the art that the configuration of the present invention can be varied and modified within the scope of the technical concept of the present invention.

Claims

1. A detector unit for detecting the voltage of a measurement target; and A temperature compensation unit that compensates for changes in voltage information measured by the above detection unit according to temperature and outputs it to a merging unit. A low-power instrumentation transformer having a temperature compensation function including 2. In Paragraph 1, The above detection unit A first capacitor having a capacitance according to the distance between the measurement target and the sensor; and A second capacitor connected in series with the first capacitor and having a capacitance according to the distance between the sensor and ground A low-power instrumentation transformer having a temperature compensation function including 3. In Paragraph 2, The above temperature compensation unit A resistor having at least one resistor connected to the first capacitor and the second capacitor and having a preset resistance value; and A variable resistor connected to the above resistor and having a resistance value that varies according to temperature A low-power instrumentation transformer having a temperature compensation function including 4. In Paragraph 3, A low-power measuring transformer having a temperature compensation function formed on a single printed circuit board, wherein the second capacitor, the resistor, and the variable resistor are formed on a single printed circuit board.

5. In Paragraph 4, The above variable resistor is a low-power measuring transformer having a temperature compensation function that varies the resistance value in proportion to the temperature.

6. In Paragraph 4, The above variable resistor is a low-power measuring transformer having a temperature compensation function, wherein the above variable resistor is composed of a thin-film resistor formed of platinum having a resistance value that varies according to temperature on the above printed circuit board.

7. In Paragraph 4, The above resistance part A first resistor connected to the first capacitor and the second capacitor and having a preset resistance value; and A second resistor connected between the above variable resistor and ground, having a preset resistance value A low-power instrumentation transformer having a temperature compensation function including 8. In Paragraph 7, The above first resistor and the above second resistor are a low-power measuring transformer having a temperature compensation function, which is composed of thin-film resistors on the printed circuit board.

9. In Paragraph 1, The above merging unit is a low-power measurement transformer having a temperature compensation function that integrates measured result values, converts them into digital form, and transmits them in a preset communication protocol format.

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