Standard device for verification of track insulation measuring instrument

Abstract

The utility model discloses an etalon for verification of a track insulation measuring instrument, and the etalon comprises an MCU processor, a function signal generator, a function signal amplifier, a simulation steel rail resistor, a simulation insulation joint resistor, and a simulation ballast bed resistor, a first input end of the function signal generator is connected with a signal output pin of the MCU processor, and a second input end of the function signal generator is connected with a signal output pin of the MCU processor. The output end of the function signal generator is connected with the input end of the function signal amplifier, the output end of the function signal amplifier is connected in series with the simulation insulation joint resistor through the simulation steel rail resistor, and the simulation ballast bed resistor is connected in parallel with the simulation insulation joint resistor; the standard device further comprises a digital voltmeter and a digital ampere meter, the digital voltmeter is connected with the analog insulation joint resistor in parallel, and the digital ampere meter is connected with the analog insulation joint resistor in series.

Description

Technical Field

[0001] The present application belongs to the field of electrical measurement technology, and specifically relates to a standard device for calibrating a track insulation measuring instrument. Background Art

[0002] Existing track insulation measuring instruments have the following shortcomings during the calibration process: 1. Manual operation is complex, test efficiency is low, and it is difficult to quickly switch between different test conditions; 2. The accuracy is insufficient and it is easily affected by human factors, resulting in poor consistency and reliability of test results; 3. It is difficult to fully simulate the various electrical characteristics of actual tracks, which limits the comprehensive evaluation of the measuring instrument performance. Utility Model Content

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a standard for calibrating a track insulation measuring instrument, which can achieve high-precision calibration of the track insulation measuring instrument.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] A standard for calibrating a track insulation measuring instrument, comprising: an MCU processor, a function signal generator, a function signal amplifier, a simulated rail resistance, a simulated insulation joint resistance, and a simulated track bed resistance, wherein a first input end of the function signal generator is connected to a signal output pin of the MCU processor, an output end of the function signal generator is connected to an input end of the function signal amplifier, the output end of the function signal amplifier is connected in series with the simulated insulation joint resistance via the simulated rail resistance, and the simulated track bed resistance is connected in parallel with the simulated insulation joint resistance; the standard also comprises a digital voltmeter and a digital ammeter, the digital voltmeter is connected in parallel with the simulated insulation joint resistance, and the digital ammeter is connected in series with the simulated insulation joint resistance.

[0006] Optionally, the function signal generator includes: a first amplifier, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a seventh capacitor, an eighth capacitor and a second amplifier, wherein the positive power pin of the first amplifier is connected to a +12V power supply, the negative power pin of the first amplifier is connected to the power supply, the positive input terminal of the first amplifier is connected to the signal output pin of the MCU processor to form a first node, the first end of the second resistor is connected to the first node, and the second end of the second resistor is connected to the first ground terminal; the first end of the third resistor is connected to the output terminal of the first amplifier to form a second node, and the reverse input terminal of the first amplifier is connected to the second node to form a negative feedback; the second end of the third resistor is connected to the first end of the eighth capacitor, the second end of the eighth capacitor is connected to the positive input terminal of the second amplifier to form a third node, the first end of the fourth resistor is connected to the third node, and the second end of the fourth resistor is connected to the sixth ground terminal; the first end of the fifth resistor is connected to the negative input terminal of the second amplifier to form a fourth node, and the second end of the fifth resistor is connected to the sixth ground terminal; the first end of the sixth resistor is connected to the output terminal of the second amplifier to form a fifth node, and the second end of the sixth resistor is connected to the fourth node; the first end of the seventh resistor is connected to the fifth node, and the second end of the seventh resistor is connected to the fifth ground terminal via the seventh capacitor.

[0007] Optionally, the function signal amplifier includes: a third amplifier, a ninth capacitor, a tenth capacitor, an eleventh capacitor, a twelfth capacitor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a first diode and a second diode, wherein the first end of the ninth capacitor is connected to the output end of the function signal generator, the second end of the ninth capacitor is connected to the first end of the eighth resistor, the second end of the eighth resistor is connected to the reverse input end of the third amplifier to form a sixth node, the first end of the ninth resistor is connected to the sixth node, the second end of the ninth resistor is connected to the output end of the third amplifier to form an eighth node, the tenth capacitor is connected in parallel with the ninth resistor, the first end of the tenth resistor is connected to the positive input end of the third amplifier to form a seventh node, and the tenth resistor is The second end is connected to the eighth ground end, the eleventh capacitor is connected to the tenth resistor in parallel, the first end of the eleventh resistor is connected to the seventh node, the second end of the eleventh resistor is connected to the ninth ground end, the first end of the thirteenth resistor is connected to the eighth node, the second end of the thirteenth resistor is connected to the ninth ground end, the anode of the second diode is connected to the inverting input end of the third amplifier, the cathode of the second diode is connected to the seventh node, the first diode is connected to the second diode in parallel, the cathode of the first diode is connected to the inverting input end of the third amplifier, and the anode of the first diode is connected to the seventh node; the first end of the twelfth resistor is connected to the negative power supply pin of the third amplifier, the second end of the twelfth resistor is connected to the power supply, and the twelfth capacitor is connected in parallel to both ends of the twelfth resistor.

[0008] Optionally, the MCU processor is connected to an external clock circuit, and the external clock circuit includes: a first crystal oscillator, a first resistor, a third capacitor and a fourth capacitor, wherein:

[0009] The first end of the crystal oscillator is connected to the second input pin of the MCU processor, the second end of the crystal oscillator is connected to the second output pin of the MCU processor, the first end of the third capacitor is connected to the second input pin of the MCU processor, the second end of the third capacitor is connected to the third ground terminal, the first end of the fourth capacitor is connected to the second output pin of the MCU processor, the second end of the fourth capacitor is connected to the third ground terminal, the first end of the first resistor is connected to the positive reference voltage pin of the MCU processor, and the second end of the first resistor is connected to the negative reference voltage pin of the MCU processor.

[0010] Optionally, the MCU processor is also connected to a first decoupling circuit and a second decoupling circuit, wherein the first decoupling circuit includes: a first capacitor, the first end of the first capacitor is connected to the digital power pin of the MCU processor, and the second end of the first capacitor is connected to the second ground end; the second decoupling circuit includes: a second capacitor, the first end of the second capacitor is connected to the analog power pin of the MCU processor, and the second end of the second capacitor is connected to the first ground end.

[0011] Optionally, the MCU processor is also connected to an oscillation circuit, which includes: a fifth capacitor, a sixth capacitor and a second crystal oscillator, wherein the first end of the fifth capacitor is connected to the first input pin of the MCU processor, the second end of the fifth capacitor is connected to the seventh ground terminal, the first end of the sixth capacitor is connected to the first output pin of the MCU processor, the second end of the sixth capacitor is connected to the seventh ground terminal, and the second crystal oscillator is connected in parallel with the first input pin and the first output pin of the MCU processor.

[0012] Optionally, the standard further includes: a frequency measurer, and the frequency measurer is connected to the second input terminal of the function signal generator.

[0013] Optionally, the standard further includes: an automatic measurement module, the automatic measurement module is electrically connected to the MCU processor, and the automatic measurement module includes a relay group and a stepper motor.

[0014] Optionally, the standard device further includes: a wireless communication module, and the wireless communication module is connected to the serial communication pin of the MCU processor.

[0015] Optionally, the standard device further includes a host computer, and the host computer is wirelessly connected to the MCU processor via the wireless communication module.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] This application integrates an MCU processor, a function signal generator, a function signal amplifier, and an analog resistor network, along with components such as a digital voltmeter and ammeter, to automatically and accurately generate and measure test signals, thereby achieving high-precision calibration of track insulation measuring instruments. Furthermore, with the help of the relay group and stepper motor in the automatic measurement module, different test conditions can be quickly switched to simulate the various electrical characteristics of actual tracks, improving the automation level of the calibration process, test efficiency, and data accuracy, reducing human error, and ensuring the consistency and reliability of test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1This is a schematic structural diagram of a standard device for calibrating a rail insulation measuring instrument provided by one embodiment of the present application;

[0019] Figure 2 This is another exemplary circuit diagram of a function signal generator provided by the present application;

[0020] Figure 3 This is another circuit structure diagram of a function signal amplifier provided as an example in the present application.

[0021] The following are the descriptions of the reference numerals:

[0022] 10. MCU processor; 20. Function signal generator; 30. Function signal amplifier; 40. Simulated rail resistance; 50. Simulated insulation joint resistance; 60. Simulated roadbed resistance; 70. Digital voltmeter; 80. Digital ammeter; 90. Automatic measurement module; 100. Frequency measurer; 110. Wireless communication module; 120. Host computer. DETAILED DESCRIPTION

[0023] Specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Although specific embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0024] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is based on the general principles of the specification and is not intended to limit the scope of the present application. The scope of protection of this application shall be as defined by the attached claims.

[0025] To facilitate understanding of the embodiments of the present application, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the various drawings do not constitute a limitation on the embodiments of the present application.

[0026] Figure 1 FIG. 1 is a schematic diagram of a standard device for measuring rail insulation provided by an exemplary embodiment of the present application. Figure 1As shown, the standard device includes: an MCU processor 10, a function signal generator 20, a function signal amplifier 30, a simulated rail resistance 40, a simulated insulation node resistance 50 and a simulated track bed resistance 60, wherein the first input end of the function signal generator 20 is connected to the signal output pin of the MCU processor 10, the output end of the function signal generator 20 is connected to the input end of the function signal amplifier 30, the output end of the function signal amplifier 30 is connected in series with the simulated insulation node resistance 50 via the simulated rail resistance 40, and the simulated track bed resistance 60 is connected in parallel with the simulated insulation node resistance 50; the standard device also includes a digital voltmeter 70 and a digital ammeter 80, the digital voltmeter 70 is connected in parallel with the simulated insulation node resistance 50, and the digital ammeter 80 is connected in series with the simulated insulation node resistance 50.

[0027] In this embodiment, the MCU processor 10 provides a reference signal to the function signal generator 20, causing it to generate a specific test signal. This signal, after being amplified by the function signal amplifier 30, is applied to an equivalent circuit composed of a simulated rail resistance 40, a simulated insulation resistance, and a simulated track bed resistance 60, which simulates the electrical characteristics of actual track. This creates an environment that accurately mimics the electrical characteristics of actual track. Through precise signal generation and measurement, the standard device described in this embodiment enables high-precision calibration of track insulation measuring instruments, ensuring the accuracy of their measurement results.

[0028] In addition, the present application provides a digital voltmeter 70 and a digital ammeter 80, so that the standard can accurately measure the voltage and current values ​​of the analog circuit under different test conditions. These measurements have the following effects on the calibration of the track insulation measuring instrument:

[0029] 1. Digital voltmeter 70 is connected in parallel with analog insulation resistance 50 to accurately measure the voltage across it. Digital ammeter 80 is connected in series with analog insulation resistance 50 to accurately measure the current flowing through it. The data provided by these two meters serves as a standard reference value for comparison with the readings of the calibrated track insulation measuring instrument.

[0030] 2. By comparing the known voltage and current values ​​generated by the standard with the measurement results of the rail insulation meter, the accuracy of the meter can be evaluated. If the readings of the meter deviate from those of the standard, the meter needs to be adjusted or calibrated to ensure that it can provide accurate and reliable measurement results in actual applications.

[0031] 3. During the test process, if the voltage or current value is found to be abnormal, the data from these instruments can be used to help locate the problem, such as determining whether it is a problem with the signal source or the circuit connection, thereby facilitating quick troubleshooting.

[0032] 4. The recorded voltage and current data can be uploaded to the host computer for further processing and analysis, which helps to form a comprehensive test report and provide a basis for subsequent maintenance and improvement.

[0033] In summary, the digital voltmeter 70 and the digital ammeter 80 play the role of measurement, calibration and monitoring in the standard instrument, which can ensure that the track insulation measuring instrument can meet the expected accuracy requirements during calibration.

[0034] In another exemplary embodiment, Figure 2 As shown, the function signal generator 20 includes: a first amplifier U1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a seventh capacitor C7, an eighth capacitor C8 and a second amplifier U2, wherein the positive power pin of the first amplifier U1 is connected to a +12V power supply, the negative power pin of the first amplifier U1 is connected to a -12V power supply, the positive input terminal of the first amplifier U1 is connected to the signal output pin PTA of the MCU processor to form a first node N1, the first end of the second resistor R2 is connected to the first node N1, and the second end of the second resistor R2 is connected to the first ground terminal GND1; the first end of the third resistor R3 is connected to the output terminal of the first amplifier U1 to form a second node N2, and the inverting input terminal of the first amplifier U1 is connected to the second node N2 to form Negative feedback; the second end of the third resistor R3 is connected to the first end of the eighth capacitor C8, the second end of the eighth capacitor C8 is connected to the positive input end of the second amplifier U2 to form a third node N3, the first end of the fourth resistor R4 is connected to the third node N3, and the second end of the fourth resistor R4 is connected to the sixth ground end GND6; the first end of the fifth resistor R5 is connected to the reverse input end of the second amplifier U2 to form a fourth node N4, and the second end of the fifth resistor R5 is connected to the sixth ground end GND6; the first end of the sixth resistor R6 is connected to the output end of the second amplifier U2 to form a fifth node N5, and the second end of the sixth resistor R6 is connected to the fourth node N4; the first end of the seventh resistor R7 is connected to the fifth node N5, and the second end of the seventh resistor R7 is connected to the fifth ground end GND5 via the seventh capacitor C7.

[0035] In this embodiment, the MCU processor provides a reference signal to the first amplifier U1 via the signal output pin PTA. The positive input of the first amplifier U1 is connected to the signal output pin PTA of the MCU processor, while the negative input forms a negative feedback loop with the output, thereby forming a non-inverting amplifier that can stably amplify the reference signal provided by the MCU processor.

[0036] The third resistor R3 and the eighth capacitor C8 form an RC network that filters and shapes the amplified reference signal output by the first amplifier U1. Furthermore, the eighth capacitor C8 acts as a DC blocker and an AC passer, ensuring that only the AC component of the amplified reference signal is transmitted to the positive input of the second amplifier U2. The second resistor R2 acts as a current-limiting resistor, providing a limited current-limiting effect. It prevents high currents caused by unexpected conditions (such as short circuits) from flowing directly into the MCU processor, thereby protecting the MCU from damage.

[0037] The second amplifier U2 is also a non-inverting amplifier, and its positive input terminal receives the reference signal amplified by the first amplifier U1.

[0038] The fifth resistor R5 and the sixth resistor R6 form a voltage divider network that can set a specific DC bias voltage at the fourth node N4, ensuring that the second amplifier U2 operates at an appropriate static operating point, thereby ensuring the linearity and stability of the output signal. Furthermore, one end of the sixth resistor R6 is connected to the output of the second amplifier U2, and the other end is connected to the inverting input of the second amplifier U2 via the fourth node N4, effectively forming a local feedback path. This negative feedback helps stabilize the operation of the second amplifier U2, reduces distortion, and increases the input impedance of the second amplifier U2.

[0039] The fourth resistor R4 also acts as a bias resistor, helping to determine the potential at the positive input of the second amplifier U2, ensuring that the second amplifier U2 is at a suitable quiescent operating point. This helps maintain the linearity of the output of the second amplifier U2 and reduces distortion. Furthermore, the fourth resistor R4 provides a DC path to ground for the positive input of the second amplifier U2, ensuring that the second amplifier U2 maintains a stable DC level when no AC signal is present.

[0040] The seventh resistor R7 serves as a load resistor for the second amplifier U2, helping to stabilize the output signal of the second amplifier U2 and limiting the output current to prevent overload. Furthermore, the seventh resistor R7 and the seventh capacitor C7 form an RC network to filter out high-frequency noise or unnecessary high-frequency components from the amplified reference signal output by the second amplifier U1, thereby improving the purity of the output signal of the second amplifier U2.

[0041] Furthermore, the present application describes in detail the working principle of the function signal generator 20:

[0042] The MCU processor can generate different reference signals according to a preset program or external command, such as a sine wave, a square wave, or a triangle wave. The operation of the function signal generator 20 begins with the signal output of the MCU processor. The MCU processor sends the generated reference signal to the positive input terminal of the first amplifier U1 through its signal output pin PTA. The reference signal is amplified by the first amplifier U1 to obtain an amplified reference signal. Before entering the second amplifier U2, the amplified reference signal is first filtered by the eighth capacitor C8 and smoothed by the seventh capacitor C7. Then, its signal amplitude and characteristics are further adjusted in the second amplifier U2. Finally, the adjusted amplified reference signal is output through the output terminal of the second amplifier U2 to achieve further signal amplification.

[0043] In summary, the present application amplifies the reference signal provided by the MCU processor by setting a two-stage amplifier, thereby ensuring that the output function signal has sufficient amplitude to meet the requirements.

[0044] In another exemplary embodiment, Figure 3As shown, the function signal amplifier 30 includes: a third amplifier U3, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a twelfth capacitor C12, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a first diode D1 and a second diode D2, wherein a first end of the ninth capacitor C9 is connected to the output end of the function signal generator 20, a second end of the ninth capacitor C9 is connected to the first end of the eighth resistor R8, a second end of the eighth resistor R8 is connected to the inverting input end of the third amplifier U3 to form a sixth node N6, a first end of the ninth resistor R9 is connected to the sixth node N6, a second end of the ninth resistor R9 is connected to the output end of the third amplifier U3 to form an eighth node N8, the tenth capacitor C10 is connected in parallel with the ninth resistor R9, a first end of the tenth resistor R10 is connected to the positive input end of the third amplifier U3 to form a seventh node N7, and the tenth resistor R1 The second end of the first diode D2 is connected to the inverting input terminal of the third amplifier U3, and the cathode of the second diode D2 is connected to the seventh node N7. The first diode D1 and the second diode D2 are connected in parallel. The cathode of the first diode D1 is connected to the inverting input terminal of the third amplifier U3, and the anode of the first diode D1 is connected to the seventh node N7. The first end of the twelfth resistor R12 is connected to the negative power supply pin of the third amplifier, and the second end of the twelfth resistor R12 is connected to the power supply VCC. The twelfth capacitor C12 is connected in parallel to both ends of the twelfth resistor R12.

[0045] In this embodiment, the ninth capacitor C9 is arranged between the input end of the function signal generator 20 and the function signal amplifier 30, and can be used to isolate DC and pass AC, ensuring that only the AC part of the amplified function signal can be transmitted from the function signal generator 20 to the function signal amplifier 30.

[0046] The tenth capacitor C10 and the ninth resistor R9 are connected in parallel to form an RC network, which can be used to stabilize the frequency response characteristics of the third amplifier U3. By appropriately selecting the values ​​of the tenth capacitor C10 and the ninth resistor R9, a zero or a pole can be introduced at a specific frequency point, thereby improving the phase margin of the third amplifier U3, preventing oscillation, and improving stability. In addition, the tenth capacitor C10 and the ninth resistor R9 connected in parallel can also act as a low-pass filter, allowing only low-frequency signals in the amplified reference signal to pass through, while attenuating high-frequency noise and unwanted high-frequency components, thereby helping to purify the output signal and reduce interference and distortion.

[0047] The tenth resistor R10 and the eleventh capacitor C11 are connected in parallel to form an RC network, which can be used to provide a stable DC bias point for the third amplifier U3. The tenth resistor R10 can ensure the setting of the static operating point, so that the third amplifier U3 can maintain a suitable static current state when there is no AC signal. The eleventh capacitor C11 can provide a low impedance path to ground in the high frequency band, which helps to reduce the gain of the third amplifier U3 at high frequencies, prevent self-oscillation, and increase the phase margin, thereby improving stability.

[0048] The twelfth capacitor C12 and the twelfth resistor R12 are connected in parallel to form an RC filter network. The twelfth capacitor C12 acts as a decoupling capacitor, capable of filtering out high-frequency noise and ripple in the power signal provided by the power supply VCC (high-frequency components in the power signal can cause output signal distortion or instability). The twelfth capacitor C12 provides a low-impedance path, allowing high-frequency noise in the power signal to be directly bypassed to ground through the negative power input terminal of the third amplifier U3, thereby maintaining the stability of the supply voltage. The twelfth capacitor C12 helps reduce the impact of transient changes in the power signal on the performance of the third amplifier U3, thereby improving the operating stability and reliability of the third amplifier U3.

[0049] The twelfth resistor R12 provides a discharge path for the twelfth capacitor C12. When the power supply VCC is turned off, the charge in the twelfth capacitor C12 can be slowly discharged through the twelfth resistor R12 rather than being immediately lost. This prevents reverse current surges caused by sudden power outages and protects the third amplifier U3 and other sensitive components from damage. Furthermore, when the power supply VCC is turned on, the twelfth resistor R12 can also help limit the initial charging current, achieving a soft start and preventing high current surges in the power supply system.

[0050] The function signal generator 20 is responsible for generating a specific signal waveform, such as a sine wave, square wave, or triangle wave. Although the function signal generator 20 uses an amplifier to increase the amplitude of the reference signal generated by the MCU processor, the signal generated by the function signal generator 20 needs to be further processed to meet specific requirements in actual applications, such as higher power, more stable output, or specific waveform adjustment.

[0051] The thirteenth resistor R13 acts as a load resistor at the output of the third amplifier U3, limiting the output current and providing a defined load impedance. This helps stabilize the output voltage of the third amplifier U3, ensuring proper operation under varying load conditions. Furthermore, by grounding the thirteenth resistor R13, the output signal of the third amplifier U3 is attenuated to a certain extent. This attenuation helps match the output of the third amplifier U3 with the input range of subsequent circuits or measurement equipment, thereby preventing overload or signal distortion.

[0052] The first diode D1 and the second diode D2 are connected in parallel to provide overvoltage protection for the third amplifier U3. When an abnormally high voltage appears at the input of the third amplifier U3, the first diode D1 and the second diode D2 conduct, limiting the amplitude of the input voltage and preventing damage to the third amplifier U3. For example, if the voltage at the inverting input of the third amplifier U3 becomes too high, the second diode D2 conducts, directing the excess current to the forward input and dissipating it through the ground line (GND8 or GND9). Similarly, if the voltage at the forward input becomes too high, the first diode D1 conducts, directing the excess current to the inverting input. Furthermore, the first diode D1 and the second diode D2 provide a clamping function, limiting the amplitude of the input signal to the third amplifier U3. This helps keep the voltage at the input of the third amplifier U3 within a safe range and prevents nonlinear distortion or other problems caused by excessive input voltage.

[0053] It's worth noting that although the function signal generator 20 already includes an amplifier for preliminary signal amplification, to achieve the signal characteristics required for the final application, a function signal amplifier 30 is still required for more precise control and adjustment. The function signal amplifier 30 can provide higher gain, improve signal quality, and adjust signal characteristics, ensuring that the output signal meets strict testing standards and the requirements of the actual use environment.

[0054] In summary, the function signal generator 20 is responsible for the basic generation and preliminary amplification of the function signal, while the function signal amplifier 30 is to ensure that the signal has sufficient strength and correct characteristics before being transmitted to the load. The two have clear division of labor and work together to ensure the quality and applicability of the output signal.

[0055] In another exemplary embodiment, the MCU processor 10 is connected to an external clock circuit, which includes: a first crystal oscillator Y1, a first resistor R1, a third capacitor C3 and a fourth capacitor C4, wherein the first end of the crystal oscillator Y1 is connected to the second input pin IN2 of the MCU processor 10, the second end of the crystal oscillator Y1 is connected to the second output pin OUT2 of the MCU processor 10, the first end of the third capacitor C3 is connected to the second input pin IN2 of the MCU processor 10, the second end of the third capacitor C3 is connected to the third ground terminal GND3, the first end of the fourth capacitor C4 is connected to the second output pin OUT2 of the MCU processor 10, the second end of the fourth capacitor C4 is connected to the third ground terminal GND3, the first end of the first resistor R1 is connected to the positive reference voltage pin VREF+ of the MCU processor 10, and the second end of the first resistor R1 is connected to the negative reference voltage pin VREF- of the MCU processor 10.

[0056] In this embodiment, the first crystal oscillator Y1 utilizes its inherent mechanical vibration characteristics to generate a stable oscillation signal at a specific frequency. This signal serves as the clock source for the MCU processor 10, determining the speed and synchronization of the MCU's internal operations. A first end of the first crystal oscillator Y1 is connected to the second input pin IN2 of the MCU processor 10, and a second end is connected to the second output pin OUT2, forming a feedback path that enables the MCU processor 10 to initiate and maintain oscillation of the crystal oscillator.

[0057] The third capacitor C3 and the fourth capacitor C4, together with the first crystal oscillator Y1, form a parallel resonant circuit that helps the first crystal oscillator Y1 start oscillation and maintain a stable oscillation frequency. Furthermore, by adjusting the values ​​of the third capacitor C3 and the fourth capacitor C4, the operating frequency of the first crystal oscillator Y1 can be fine-tuned within a certain range.

[0058] In summary, the external clock circuit can provide a high-precision, low-drift clock signal for the MCU processor 10, while ensuring that the reference voltage required by the internal analog circuit of the MCU processor 10 is stable and reliable.

[0059] In another exemplary embodiment, the MCU processor 10 is further connected to a first decoupling circuit, which includes a first capacitor C1, a first end of the first capacitor C1 is connected to the digital power pin DVCC of the MCU processor 10, and a second end of the first capacitor C1 is connected to the second ground terminal GND2.

[0060] In this embodiment, when the MCU processor 10 performs various operations, especially when switching between different states (such as from idle to active mode), it consumes more current, which can cause transient fluctuations in the local power supply voltage. The first capacitor C1 provides a low-impedance path to quickly absorb these transient currents and bypass them to ground, thereby reducing the impact on the DVCC pin and maintaining a stable power supply voltage.

[0061] In another exemplary embodiment, the MCU processor 10 is further connected to a second decoupling circuit, which includes a second capacitor C2, a first end of the second capacitor C2 is connected to the analog power pin AVCC of the MCU processor 10, and a second end of the second capacitor C2 is connected to the first ground terminal GND1.

[0062] In this embodiment, the second capacitor C2 can filter out high-frequency noise and ripple in the analog power signal supplied to the MCU processor 10, thereby providing a purer voltage for the MCU processor 10. In addition, the second capacitor C2 can quickly respond to and absorb transient current changes generated by the MCU processor 10 during operation, preventing these changes from causing a sudden drop or rise in the power supply voltage of the MCU processor 10, thereby ensuring that the internal circuits of the MCU processor 10 receive a stable power supply voltage.

[0063] In another exemplary embodiment, the MCU processor 10 is also connected to an oscillation circuit, which includes a fifth capacitor C5, a sixth capacitor C6 and a second crystal oscillator Y2, wherein the first end of the fifth capacitor C5 is connected to the first input pin IN1 of the MCU processor 10, the second end of the fifth capacitor C5 is connected to the seventh ground terminal GND7, the first end of the sixth capacitor C6 is connected to the first output pin OUT of the MCU processor 10, the second end of the sixth capacitor C6 is connected to the seventh ground terminal GND7, and the second crystal oscillator Y2 is connected in parallel with the first input pin IN1 and the first output pin OUT of the MCU processor 10.

[0064] In this embodiment, the fifth capacitor C5 and the sixth capacitor C6 form a parallel resonant circuit with the second crystal oscillator Y2. The fifth capacitor C5 and the sixth capacitor C6 can be used to assist the second crystal oscillator Y2 in crystal oscillation. Moreover, by adjusting the capacitance values ​​of the fifth capacitor C5 and the sixth capacitor C6, the oscillation frequency of the second crystal oscillator Y2 can be fine-tuned. In addition, the fifth capacitor C5 and the sixth capacitor C6 also act as filters to help eliminate the effects of power supply noise on the second crystal oscillator Y2, thereby ensuring that the second crystal oscillator Y2 can provide a high-quality clock signal to the MCU processor 10.

[0065] It should also be noted that the fifth capacitor C5 and the sixth capacitor C6 can provide a stable bias voltage for the crystal oscillator Y2 by being grounded. In the absence of an AC signal, the fifth capacitor C5 and the sixth capacitor C6 can help maintain a DC bias condition, thereby contributing to the normal starting and oscillation stability of the second crystal oscillator Y2, thereby enabling the MCU processor 10 to obtain an accurate, stable and anti-interference clock source.

[0066] In another exemplary embodiment, the standard further includes an automatic measurement module 90 , which is electrically connected to the MCU processor 10 , and includes a relay group and a stepper motor.

[0067] In this embodiment, the relay group is connected to a digital I / O pin of the MCU processor 10 via a control circuit. (In specific applications, the specific pin selection depends on the specific MCU model; the available digital I / O pins and their functions can be determined by consulting the relevant MCU datasheet.) The relay group comprises multiple relays, each connected to a digital I / O pin of the MCU processor 10. Each relay can control the closing or opening of one or more contacts. The MCU processor 10 sends signals via the digital I / O pins to control the relay states (for example, if the pin is set to a high level, the relay closes; if the pin is set to a low level, the relay opens). This allows for switching between different values ​​of track resistance as needed to simulate different track conditions. This allows for simulating test scenarios under a variety of track electrical characteristics, thereby facilitating a comprehensive evaluation of the measuring instrument's performance under various conditions.

[0068] Similarly, the stepper motor is connected to the digital I / O pin of the MCU processor 10 through a control line (usually including a direction control line, a step pulse line, etc.). The MCU processor 10 drives the stepper motor to rotate, so that the stepper motor moves to a specified position, thereby replacing the insulation resistance of different resistance values.

[0069] For example, assume that there are three different roadbed resistance values: R1=50Ω, R2=100Ω, and R3=200Ω.

[0070] The relay group includes three relays, namely relay 1, relay 2 and relay 3. Each relay controls the access circuit of the track bed resistor of the above resistance value. Among them, relay 1 controls R1 to access the circuit, relay 2 controls R2 to access the circuit, and relay 3 controls R3 to access the circuit.

[0071] The MCU processor sends signals through digital I / O pins to control the status of these relays. For example:

[0072] When relay 1 is set to high (closed) and the other relays are set to low (open), the track bed resistance is 50Ω.

[0073] When relay 2 is set to high (closed) and the other relays are set to low (open), the track bed resistance is 100Ω.

[0074] When relay 3 is set to high level (closed) and the other relays are set to low level (open), the track bed resistance is 200Ω.

[0075] Insulation resistance replacement:

[0076] Assume there are three different insulation resistance values: R4=1MΩ, R5=2MΩ, R6=4MΩ.

[0077] The stepper motor can be moved to a specified position to replace these insulation resistance sections with different resistance values.

[0078] The MCU processor selects the appropriate insulation resistance by controlling the position of the stepper motor. For example:

[0079] When the stepper motor moves to position 1, R4 (1MΩ) is selected as the insulation junction resistor.

[0080] When the stepper motor moves to position 2, R5 (2MΩ) is selected as the insulation junction resistor.

[0081] When the stepper motor moves to position 3, R6 (4MΩ) is selected as the insulation junction resistor.

[0082] Specific operation steps example:

[0083] Initial state: All relays are disconnected and the stepper motor is in the initial position.

[0084] Test scenario 1: Track bed resistance 50Ω, insulation joint resistance 1MΩ

[0085] The MCU processor sets relay 1 to high level and other relays to low level.

[0086] The MCU processor controls the stepper motor to move to position 1, takes measurements, and records the data.

[0087] Test scenario 2: Track bed resistance 100Ω, insulation joint resistance 2MΩ

[0088] The MCU processor sets relay 2 to high level and other relays to low level.

[0089] The MCU processor controls the stepper motor to move to position 2, takes measurements, and records the data.

[0090] Test scenario 3: Track bed resistance 200Ω, insulation joint resistance 4MΩ

[0091] The MCU sets relay 3 to high level and other relays to low level.

[0092] The MCU controls the stepper motor to move to position 3, takes measurements, and records the data.

[0093] In this way, the standard can quickly and accurately switch between different resistance values, thereby simulating a variety of test scenarios for rail electrical characteristics, ensuring that the rail insulation measuring instrument can cover various actual working conditions during the calibration process.

[0094] In summary, the automatic measurement module 90, through the coordinated work of the relay group and the stepper motor, can achieve rapid and accurate switching of different resistance values ​​of the track bed electronics and insulation node resistance, thereby significantly improving the degree of automation, test efficiency and data accuracy of the track insulation measuring instrument calibration process, reducing human errors, and ensuring the consistency and reliability of the test results.

[0095] In another exemplary embodiment, the standard further includes a frequency measurer 100 , which is connected to the second input terminal of the function signal generator 20 and is used to measure the frequency of the signal generated by the function signal generator 20 .

[0096] In this embodiment, the standard instrument is used to calibrate the measuring instrument to ensure the accuracy of its measurement results. The frequency meter 100 can directly measure the frequency of the signal generated by the function signal generator 20 and compare it with a preset standard frequency to verify whether the function signal generator 20 is operating as expected. If the signal frequency deviates, the calibration results of the measuring instrument will be affected.

[0097] For example, it is assumed that the preset standard frequency is 50 Hz.

[0098] The frequency output by the function signal generator 20 is as follows:

[0099] Test point 1: 49.8 Hz

[0100] Test point 2: 50.2 Hz

[0101] Test point 3: 50.0 Hz

[0102] Test point 4: 49.9 Hz

[0103] Test point 5: 50.1 Hz

[0104] Frequency deviation calculation:

[0105] The frequency deviation of each test point can be calculated by the following formula:

[0106] Frequency deviation = |actual frequency − preset standard frequency |

[0107] Calculate the frequency deviation for each test point:

[0108] Test point 1: |49.8Hz−50Hz|=0.2Hz

[0109] Test point 2: |50.2Hz−50Hz|=0.2Hz

[0110] Test point 3: |50.0Hz−50Hz|=0.0Hz

[0111] Test point 4: |49.9Hz−50Hz|=0.1Hz

[0112] Test point 5: |50.1Hz−50Hz|=0.1Hz

[0113] Frequency deviation evaluation:

[0114] According to the above calculation, we can see that the frequency deviation is as follows:

[0115] Test point 1: 0.2 Hz

[0116] Test point 2: 0.2 Hz

[0117] Test point 3: 0.0 Hz

[0118] Test point 4: 0.1 Hz

[0119] Test point 5: 0.1 Hz

[0120] If the frequency deviation exceeds a certain allowable error range (e.g., ±0.1 Hz), the function signal generator 20 is considered to be operating as expected and requires adjustment or repair. In the above example, the frequency deviation between test points 1 and 2 exceeds 0.1 Hz, so further inspection and correction are required.

[0121] From the above data examples, it can be seen that the present application can ensure that the frequency of the signal generated by the function signal generator 20 is accurate by setting the frequency measurer 100, thereby improving the calibration accuracy of the standard for the measuring instrument.

[0122] In another exemplary embodiment, the standard further includes a wireless communication module 110 , and the wireless communication module 110 is connected to a serial communication pin (eg, UART or SPI) of the MCU processor 10 .

[0123] In this embodiment, the wireless communication module 110 can use any one of a variety of wireless technologies, such as Bluetooth, Zigbee, and 5G, to achieve wireless connection between the standard and external devices. For example, via Bluetooth or Zigbee, the standard can exchange data with a laptop computer locally; via 5G, the standard can quickly upload large amounts of calibration data to the "Railway Metrology Management System" to achieve remote monitoring and data analysis, thereby facilitating data transmission.

[0124] In another exemplary embodiment, the standard device further includes a host computer 120 , and the host computer 120 is wirelessly connected to the MCU processor 10 via the wireless communication module 110 .

[0125] In this embodiment, the host computer 120 is responsible for receiving data from the standard instrument and processing, storing, and analyzing it. The host computer 120 can categorize, store, and organize the calibrated measuring instrument data and provide an export function for subsequent use. Furthermore, the host computer 120 can upload the processed data to the "Railway Metrology Management System" for centralized data management and analysis. Furthermore, the host computer 120 can conveniently share data with other systems or devices.

[0126] The above embodiments are intended only to illustrate the technical concepts and features of this application. Their purpose is to enable those familiar with the art to understand the content of this application and implement it accordingly. They are not intended to limit the scope of protection of this application. Any equivalent changes or modifications made in accordance with the spirit of this application shall be included in the scope of protection of this application.

Claims

1. A standard device for calibrating rail insulation measuring instruments, characterized in that: The standard device includes: MCU processor (10), function signal generator (20), function signal amplifier (30), simulated rail resistance (40), simulated insulation joint resistance (50) and simulated track bed resistance (60), wherein: The first input end of the function signal generator (20) is connected to the signal output pin of the MCU processor (10), the output end of the function signal generator (20) is connected to the input end of the function signal amplifier (30), the output end of the function signal amplifier (30) is connected in series with the simulated insulation node resistor (50) via the simulated rail resistor (40), and the simulated roadbed resistor (60) is connected in parallel with the simulated insulation node resistor (50); The standard device further comprises a digital voltmeter (70) and a digital ammeter (80), wherein the digital voltmeter (70) is connected in parallel with the analog insulation joint resistor (50), and the digital ammeter (80) is connected in series with the analog insulation joint resistor (50).

2. The standard according to claim 1, characterized in that The function signal generator (20) comprises: a first amplifier, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a seventh capacitor, an eighth capacitor, and a second amplifier, wherein: The positive power supply pin of the first amplifier is connected to a +12V power supply, the negative power supply pin of the first amplifier is connected to the power supply, the positive input terminal of the first amplifier is connected to the signal output pin of the MCU processor to form a first node, the first end of the second resistor is connected to the first node, and the second end of the second resistor is connected to the first ground terminal; the first end of the third resistor is connected to the output terminal of the first amplifier to form a second node, and the inverting input terminal of the first amplifier is connected to the second node to form negative feedback; the second end of the third resistor is connected to the first end of the eighth capacitor, and the second end of the eighth capacitor is connected to the positive input terminal of the second amplifier to form a third node; the first end of the fourth resistor is connected to the third node, and the second end of the fourth resistor is connected to the sixth ground terminal; the first end of the fifth resistor is connected to the inverting input terminal of the second amplifier to form a fourth node, and the second end of the fifth resistor is connected to the sixth ground terminal; the first end of the sixth resistor is connected to the output terminal of the second amplifier to form a fifth node, and the second end of the sixth resistor is connected to the fourth node; the first end of the seventh resistor is connected to the fifth node, and the second end of the seventh resistor is connected to the fifth ground terminal via the seventh capacitor.

3. The standard according to claim 1, characterized in that The function signal amplifier (30) comprises: a third amplifier, a ninth capacitor, a tenth capacitor, an eleventh capacitor, a twelfth capacitor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a first diode, and a second diode, wherein: The first end of the ninth capacitor is connected to the output end of the function signal generator, the second end of the ninth capacitor is connected to the first end of the eighth resistor, the second end of the eighth resistor is connected to the inverting input end of the third amplifier to form a sixth node, the first end of the ninth resistor is connected to the sixth node, the second end of the ninth resistor is connected to the output end of the third amplifier to form an eighth node, the tenth capacitor is connected in parallel with the ninth resistor, the first end of the tenth resistor is connected to the positive input end of the third amplifier to form a seventh node, the second end of the tenth resistor is connected to the eighth ground terminal, the eleventh capacitor is connected in parallel with the tenth resistor, the first end of the eleventh resistor is connected to the seventh node point, the second end of the eleventh resistor is connected to the ninth ground terminal, the first end of the thirteenth resistor is connected to the eighth node, the second end of the thirteenth resistor is connected to the ninth ground terminal, the anode of the second diode is connected to the inverting input terminal of the third amplifier, the cathode of the second diode is connected to the seventh node, the first diode and the second diode are connected in parallel, the cathode of the first diode is connected to the inverting input terminal of the third amplifier, and the anode of the first diode is connected to the seventh node; the first end of the twelfth resistor is connected to the negative power supply pin of the third amplifier, the second end of the twelfth resistor is connected to the power supply, and the twelfth capacitor is connected in parallel across the twelfth resistor.

4. The standard according to claim 1, characterized in that The MCU processor (10) is connected to an external clock circuit, and the external clock circuit includes: a first crystal oscillator, a first resistor, a third capacitor, and a fourth capacitor, wherein: The first end of the crystal oscillator is connected to the second input pin of the MCU processor (10), the second end of the crystal oscillator is connected to the second output pin of the MCU processor (10), the first end of the third capacitor is connected to the second input pin of the MCU processor (10), the second end of the third capacitor is connected to the third ground terminal, the first end of the fourth capacitor is connected to the second output pin of the MCU processor (10), the second end of the fourth capacitor is connected to the third ground terminal, the first end of the first resistor is connected to the positive reference voltage pin of the MCU processor (10), and the second end of the first resistor is connected to the negative reference voltage pin of the MCU processor (10).

5. The standard according to claim 1, characterized in that The MCU processor (10) is further connected to a first decoupling circuit and a second decoupling circuit, wherein: The first decoupling circuit comprises: a first capacitor, a first end of the first capacitor being connected to a digital power pin of the MCU processor (10), and a second end of the first capacitor being connected to a second ground end; The second decoupling circuit comprises: a second capacitor, a first end of the second capacitor being connected to an analog power pin of the MCU processor (10), and a second end of the second capacitor being connected to a first ground end.

6. The standard according to claim 1, characterized in that The MCU processor (10) is further connected to an oscillation circuit, and the oscillation circuit comprises: a fifth capacitor, a sixth capacitor, and a second crystal oscillator, wherein: The first end of the fifth capacitor is connected to the first input pin of the MCU processor (10), the second end of the fifth capacitor is connected to the seventh ground terminal, the first end of the sixth capacitor is connected to the first output pin of the MCU processor (10), the second end of the sixth capacitor is connected to the seventh ground terminal, and the second crystal oscillator is connected in parallel with the first input pin and the first output pin of the MCU processor (10).

7. The standard according to claim 1, characterized in that The standard device also includes: A frequency measurer (100) is connected to the second input end of the function signal generator (20).

8. The standard according to claim 1, characterized in that The standard device also includes: An automatic measurement module (90), the automatic measurement module (90) is electrically connected to the MCU processor (10), and the automatic measurement module (90) comprises a relay group and a stepping motor.

9. The standard according to claim 1, characterized in that The standard device also includes: A wireless communication module (110) is connected to a serial communication pin of the MCU processor (10).

10. The standard according to claim 9, characterized in that The standard device further includes a host computer (120), and the host computer (120) is wirelessly connected to the MCU processor (10) via the wireless communication module (110).

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