System and method for detecting reliability of vibration measurement cable

Abstract

The invention discloses a reliability detection system and detection method for a vibration measurement cable, and solves the problem that the reliability of the cable cannot be accurately judged by tightly depending on the detection of the insulation resistance of the cable in the existing cable reliability detection method. The output end of a vibration calibration system is connected with one end of a standard capacitor, and the vibration calibration system is used for loading a standard known voltage signal; the other end of the standard capacitor is connected with the charge acquisition system, and the standard capacitor is connected in parallel with a to-be-detected vibration measurement cable; the charge collection system is used for collecting the total charge quantity of the standard capacitance and the vibration measurement cable to be detected. According to the reliability detection system and detection method for the vibration measurement cable, the vibration measurement cable is screened by detecting the noise voltage converted by the stray capacitance of the vibration measurement cable, and the higher the noise voltage is, the larger the interference noise is and the lower the reliability is during vibration parameter acquisition of the cable; the method can accurately detect the reliability of the vibration measurement cable.

Description

Technical Field

[0001] The invention relates to a reliability detection method for a cable, and in particular to a reliability detection system and a detection method for a vibration measurement cable. Background Art

[0002] According to the requirements of the vibration measurement regulations, the cable reliability detection indicators are: cable resistance and cable insulation resistance. Most of the current detection methods are: to determine whether the cable is short-circuited, open-circuited or eaten by mice by measuring whether the cable resistance is within the specified range; and then to determine whether the cable insulation performance is good or bad by measuring whether the cable insulation resistance is not less than 500MΩ by using an ohmmeter. However, there are many factors that affect cable noise. It is unreliable to judge the performance of the cable only by relying on the above two detection indicators. Table 1 shows the insulation resistance and noise of the cable when the piezoelectric vibration sensor was not connected.

[0003] Table 1

[0004] Channel Number Insulation resistance(MΩ) Noise value (m / s2) 3 200 70 5 300 49 26 400 160 27 7 60

[0005] It can be seen from Table 1 that good insulation performance does not necessarily mean low noise; the disadvantage of the above method is that insulation resistance is a necessary standard for measuring cable performance, but relying solely on detecting cable insulation resistance cannot accurately determine the reliability of the cable. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the existing cable reliability detection method relies solely on detecting the insulation resistance of the cable and cannot accurately determine the reliability of the cable, and to provide a reliability detection system and detection method for a vibration measurement cable.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A reliability detection system for vibration measurement cables, which is special in that:

[0009] Includes vibration calibration system, standard capacitor, charge collection system and piezoelectric vibration sensor;

[0010] The output end of the vibration calibration system is connected to one end of a standard capacitor for loading a standard known voltage signal;

[0011] The other end of the standard capacitor is connected to a charge collection system;

[0012] One end of the piezoelectric vibration sensor is connected to the vibration calibration system, and the other end is connected to the charge collection system;

[0013] The charge collection system is used to collect the total charge at a location.

[0014] Furthermore, the standard known voltage signal is a sine wave signal, with a frequency of 1000 Hz and a voltage of 8V during normal vibration, and a frequency of 78.125 Hz and a voltage of 1.2V during low-frequency vibration.

[0015] Furthermore, the capacitance value of the standard capacitor is one of 500pF, 1000pF, 1500pF, and 2000pF.

[0016] At the same time, the present invention also provides a reliability detection method for a vibration measuring cable, using a reliability detection system for a vibration measuring cable, which is special in that it includes the following steps:

[0017] S1. Measure the length of the vibration measurement cable to be tested and calculate the distributed capacitance value C of the vibration measurement cable to be tested. f ; At the same time, connect the vibration measurement cable to be tested in parallel with the standard capacitor;

[0018] S2, remove the piezoelectric vibration sensor, load a standard known voltage U through the vibration calibration system, collect the standard capacitor and the total charge q of the vibration measurement cable to be detected through the charge collection system, and calculate the total capacitance value C1 of the vibration measurement cable to be detected by combining the standard known voltage U and the capacitance value C of the standard capacitor;

[0019] S3, restore the connection of the piezoelectric vibration sensor, remove the standard capacitor, remove the loaded standard known voltage U, load the rated voltage u into the piezoelectric vibration sensor, and collect the total charge Q of the piezoelectric vibration sensor and the vibration measurement cable to be detected through the charge collection system;

[0020] S4, according to the total capacitance value C1 of the vibration measurement cable to be detected in S2, the distributed capacitance value C of the vibration measurement cable to be detected in S1 f , calculate the parasitic capacitance value C of the vibration measurement cable to be detected j ;

[0021] S5. Calculate the charge q1 of the piezoelectric vibration sensor according to the rated voltage u and the capacitance of the piezoelectric vibration sensor; Calculate the charge q1 of the piezoelectric vibration sensor according to the rated voltage u and the distributed capacitance value C f Calculate the distributed capacitance charge q2 of the vibration measurement cable to be detected;

[0022] S6, calculating the charge q3 of the cable parasitic capacitance according to the total charge Q of the piezoelectric vibration sensor and the vibration measurement cable to be detected, the charge q1 of the piezoelectric vibration sensor, and the charge q2 of the distributed capacitance of the vibration measurement cable to be detected in S3;

[0023] S7, measure the parasitic capacitance value C of the cable in combination with the vibration detected in S4 jThe cable noise voltage U is calculated by the charge q3 accumulated by the cable parasitic capacitance in S6 噪 ;

[0024] S8. Collect the output voltage of the piezoelectric vibration sensor and calculate the cable noise voltage U 噪 When the ratio of the output voltage of the piezoelectric vibration sensor is not greater than 5%, the reliability of the vibration measurement cable to be detected is good; otherwise, the reliability of the vibration measurement cable to be detected is poor.

[0025] Furthermore, the formula for calculating the total capacitance value C1 of the vibration measurement cable to be detected in S2 is:

[0026] q=(C1+C)×U.

[0027] Furthermore, the formula for calculating the charge amount q3 accumulated by the cable parasitic capacitance in S6 is:

[0028] Q3=Q-q1-q2.

[0029] Further, the cable noise voltage U is calculated in S7 噪 The formula is:

[0030] U 噪 =q3 / C j .

[0031] Beneficial effects of the present invention:

[0032] 1. The reliability detection system of a vibration measurement cable of the present invention has a simple structure and good practicability.

[0033] 2. A reliability detection method for a vibration measuring cable of the present invention selects the vibration measuring cable by detecting the noise voltage converted from the parasitic capacitance of the vibration measuring cable. The cable with higher noise voltage has greater interference noise when collecting vibration parameters and lower reliability. The method of the present invention can accurately detect the reliability of the vibration measuring cable.

[0034] 3. The reliability detection method of a vibration measurement cable of the present invention also has the advantages of simple operation and fast detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of an embodiment of a reliability detection system for a vibration measurement cable of the present invention;

[0036] Figure 2 A schematic diagram of a detection system model used in an embodiment of a reliability detection method for a vibration measurement cable of the present invention;

[0037] Figure 3A standard known voltage signal waveform diagram during normal vibration in an embodiment of a reliability detection method for a vibration measurement cable of the present invention;

[0038] Figure 4 This is a waveform diagram of a standard known voltage signal during low-frequency vibration in an embodiment of a reliability detection method for a vibration measurement cable of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example

[0041] In this embodiment, a reliability detection system for a vibration measurement cable is provided. Figure 1 As shown, it includes a vibration calibration system, a standard capacitor, a charge acquisition system and a piezoelectric vibration sensor; wherein the capacitance value of the standard capacitor is 1000pF.

[0042] The output end of the vibration calibration system is connected to one end of a standard capacitor for loading a standard known voltage signal; the standard known voltage signal is a sine wave signal with a frequency of 1000 Hz and a voltage of 8 V during normal vibration and a frequency of 78.125 Hz and a voltage of 1.2 V during low-frequency vibration.

[0043] The other end of the standard capacitor is connected to the charge acquisition system, and the standard capacitor is connected in parallel with the vibration measurement cable to be detected;

[0044] One end of the piezoelectric vibration sensor is connected to the vibration calibration system, and the other end is connected to the charge collection system;

[0045] The charge collection system is used to collect the total charge at the location.

[0046] The total capacitance of the vibration measurement cable in this embodiment includes the cable parasitic capacitance and distributed capacitance. Normally, the cable parasitic capacitance is very small and can be ignored, but for some cables with poor performance, the parasitic capacitance is very large, resulting in the charging of the parasitic capacitance when the cable is shaken and insulated, making the zero-position noise value of the cable larger when it is connected to the acquisition system, sometimes even exceeding the test signal value. The specific impact on the test vibration signal is analyzed as follows:

[0047] Assume that the parasitic capacitance of the vibration measurement cable to be detected is C j , the distributed capacitance value is C f , C j and C fIf the two cables are in parallel, the total capacitance C1 of the vibration measurement cable to be tested is: C1 = C j +C f Since the physical quantity of vibration measurement is the amount of charge, let the total charge of the vibration measurement cable to be detected be q0, and the charge of the distributed capacitance of the vibration measurement cable to be detected be q2. Due to the existence of parasitic capacitance in the cable, the amount of charge that will be gathered on it is set to q3. According to the conservation formula, we can get:

[0048] q0=q2+q3;

[0049] It can be seen that due to the existence of parasitic capacitance of the cable, part of the charge generated by vibration during the test is owned by the parasitic capacitance, resulting in a smaller amount of charge actually measured, which affects the accuracy of the vibration measurement data. Therefore, such vibration measurement cables must be eliminated.

[0050] Based on the existence of the above parasitic capacitance, the load value of the charge collection system when it is unloaded is 2.3×10 -3 m / s 2 The acceleration of the -3 pC (acceleration value: equivalent charge value = 1m / s 2 :1pC). By connecting the vibration measurement cable to be detected, the equivalent charge value range is: 30~80pC. The reason for the change in charge is the existence of noise voltage in the cable.

[0051] Based on the above analysis, a reliability detection method for a vibration measuring cable in this embodiment uses a reliability detection system for a vibration measuring cable, and its model is as follows: Figure 2 As shown; specifically including the following steps:

[0052] S1. Measure the length of the vibration measurement cable to be tested and calculate the distributed capacitance value C of the vibration measurement cable to be tested. f ; At the same time, connect the vibration measurement cable to be tested in parallel with the standard capacitor;

[0053] S2. Remove the piezoelectric vibration sensor, load the standard known voltage U through the vibration calibration system, collect the standard capacitor and the total charge q of the vibration measurement cable to be tested through the charge collection system, and calculate the total capacitance value C1 of the vibration measurement cable to be tested by combining the standard known voltage U and the capacitance value C of the standard capacitor; the formula is:

[0054] q=(C1+C)×U.

[0055] Figure 3 This is the waveform diagram of the known voltage signal with normal vibration of 1kHz, 8V; Figure 4 This is the waveform diagram of the known voltage signal low-frequency vibration 78.125Hz, 1.2V.

[0056] A standard known voltage signal of normal vibration 1kHz, 8V is loaded on the vibration calibration system. The capacitance value of the standard capacitor is C=1000pF. q=12000pC is measured, and C1=500pF is obtained.

[0057] Verify the calculation method:

[0058] The standard known voltage signal is adjusted to low frequency vibration 78.125Hz, 1.2V, C and C1 are substituted into the evaluation, and the output q=1800pC is obtained. By recording the waveform value of the charge acquisition system, q is obtained to be 1790pc, which is consistent with the calculation result.

[0059] S3, restore the connection of the piezoelectric vibration sensor, remove the standard capacitor, remove the loaded standard known voltage U, load the rated voltage u into the piezoelectric vibration sensor, and collect the total charge Q of the piezoelectric vibration sensor and the vibration measurement cable to be detected through the charge collection system;

[0060] S4, according to the total capacitance value C1 of the vibration measurement cable to be detected in S2, the distributed capacitance value C of the vibration measurement cable to be detected in S1 f , calculate the parasitic capacitance value C of the vibration measurement cable to be detected j ;

[0061] S5. Calculate the charge q1 of the piezoelectric vibration sensor according to the rated voltage u and the capacitance of the piezoelectric vibration sensor; Calculate the charge q1 of the piezoelectric vibration sensor according to the rated voltage u and the distributed capacitance value C f Calculate the distributed capacitance charge q2 of the vibration measurement cable to be detected;

[0062] S6, calculate the charge q3 accumulated by the parasitic capacitance of the cable according to the total charge Q of the piezoelectric vibration sensor and the vibration measurement cable to be detected in S3, the charge q1 of the piezoelectric vibration sensor and the charge q2 of the distributed capacitance of the vibration measurement cable to be detected; the formula is:

[0063] q3=Q-q1-q2.

[0064] S7, measure the parasitic capacitance value C of the cable in combination with the vibration detected in S4 j The cable noise voltage U is calculated by the charge q3 accumulated by the cable parasitic capacitance in S6 噪 ; The formula is:

[0065] U 噪 =q3 / C j .

[0066] S8. Collect the output voltage of the piezoelectric vibration sensor and calculate the cable noise voltage U 噪When the ratio of the output voltage of the piezoelectric vibration sensor is not greater than 5%, the reliability of the vibration measurement cable to be detected is good; otherwise, the reliability of the vibration measurement cable to be detected is poor.

[0067] When selecting a vibration measurement cable, a vibration measurement cable with a low ratio of cable noise voltage to the voltage of a standard known voltage signal is selected, which has the advantage of low noise.

[0068] The present invention has the advantages of fast detection speed and good detection effect in the reliability detection of vibration cables. The reliability of the cable is judged by calculating the cable noise voltage, which is convenient for selecting and using the vibration cable and avoids the problem that the noise voltage is too large after the cable has been laid and the vibration sensor is connected, thereby affecting the data measurement accuracy.

[0069] The above description is only a specific embodiment of the present invention, and a comparison of the effects of the specific embodiments and the related comparative examples, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A reliability detection system for a vibration measurement cable, characterized in that: Includes vibration calibration system, standard capacitor, charge collection system and piezoelectric vibration sensor; The output end of the vibration calibration system is connected to one end of a standard capacitor for loading a standard known voltage signal; The other end of the standard capacitor is connected to a charge collection system; One end of the piezoelectric vibration sensor is connected to the vibration calibration system, and the other end is connected to the charge collection system; The charge collection system is used to collect the total charge at a location.

2. A reliability detection system for a vibration measurement cable according to claim 1, characterized in that: The standard known voltage signal is a sine wave signal, with a frequency of 1000 Hz and a voltage of 8 V during normal vibration, and a frequency of 78.125 Hz and a voltage of 1.2 V during low-frequency vibration.

3. A reliability detection system for a vibration measurement cable according to claim 1, characterized in that: The capacitance value of the standard capacitor is one of 500pF, 1000pF, 1500pF, and 2000pF.

4. A reliability detection method for a vibration measuring cable, using a reliability detection system for a vibration measuring cable according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Measure the length of the vibration measurement cable to be tested and calculate the distributed capacitance value C of the vibration measurement cable to be tested. f ; At the same time, connect the vibration measurement cable to be tested in parallel with the standard capacitor; S2, remove the piezoelectric vibration sensor, load a standard known voltage U through the vibration calibration system, collect the standard capacitor and the total charge q of the vibration measurement cable to be detected through the charge collection system, and calculate the total capacitance value C1 of the vibration measurement cable to be detected by combining the standard known voltage U and the capacitance value C of the standard capacitor; S3, restore the connection of the piezoelectric vibration sensor, remove the standard capacitor, remove the loaded standard known voltage U, load the rated voltage u into the piezoelectric vibration sensor, and collect the total charge Q of the piezoelectric vibration sensor and the vibration measurement cable to be detected through the charge collection system; S4, according to the total capacitance value C1 of the vibration measurement cable to be detected in S2, the distributed capacitance value C of the vibration measurement cable to be detected in S1 f , calculate the parasitic capacitance value C of the vibration measurement cable to be detected j ; S5. Calculate the charge q1 of the piezoelectric vibration sensor according to the rated voltage u and the capacitance of the piezoelectric vibration sensor; Calculate the charge q1 of the piezoelectric vibration sensor according to the rated voltage u and the distributed capacitance value C f Calculate the distributed capacitance charge q2 of the vibration measurement cable to be detected; S6, calculating the charge q3 of the cable parasitic capacitance according to the total charge Q of the piezoelectric vibration sensor and the vibration measurement cable to be detected, the charge q1 of the piezoelectric vibration sensor, and the charge q2 of the distributed capacitance of the vibration measurement cable to be detected in S3; S7, measure the parasitic capacitance value C of the cable in combination with the vibration detected in S4 j The cable noise voltage U is calculated by the charge q3 accumulated by the cable parasitic capacitance in S6 噪 ; S8. Collect the output voltage of the piezoelectric vibration sensor and calculate the cable noise voltage U 噪 When the ratio of the output voltage of the piezoelectric vibration sensor is not greater than 5%, the reliability of the vibration measurement cable to be detected is good; otherwise, the reliability of the vibration measurement cable to be detected is poor.

5. The reliability detection method of a vibration measurement cable according to claim 4, characterized in that: The formula for calculating the total capacitance value C1 of the vibration measurement cable to be detected in S2 is: q=(C1+C)×U.

6. The reliability detection method of a vibration measurement cable according to claim 4, characterized in that: The formula for calculating the charge q3 accumulated by the cable parasitic capacitance described in S6 is: q3=Q-q1-q2.

7. The reliability detection method of a vibration measurement cable according to claim 4, characterized in that: Calculate the cable noise voltage U as described in S7 噪 The formula is: IN 噪 =q3 / C j 。

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