Wire insulation defect detecting and positioning device

Abstract

The invention relates to a wire insulation defect detecting and positioning device which comprises a signal generating device (1), a signal collecting and analyzing device (2) and a test switching cable (3). The signal generating device [1] is used for providing a high-frequency signal with a certain amplitude to a tested wire; the signal collecting and analyzing device (2) collects incident high-frequency signals and reflected high-frequency signals in the wire and processes, displays and analyzes the collected incident high-frequency signals and reflected high-frequency signals. And the test switching cable (3) is connected with the signal generation device (1) and the tested lead (6) and is connected with the signal acquisition and analysis device (2) at the same time. The device provided by the invention is high in test safety, does not involve high-voltage direct current and alternating current, does not cause damage to equipment and personnel, and can discover hidden insulation defects and position the hidden insulation defects.

Description

Technical Field

[0001] The invention belongs to the technical field of testing and measurement, and relates to a wire insulation defect and positioning detection device, which is used for discovering and locating hidden insulation defects of wires. Background Art

[0002] After leaving the factory, the wires often work in complex environments such as chemistry, heat and cold, electricity, vibration, friction, external force, pollution and radiation, and due to improper maintenance and other reasons, the insulation layer will wear, age, corrode and deform, resulting in insulation failure or buried insulation failure hidden dangers. Once such failures occur, they will cause great economic losses or endanger the personal safety of related personnel. At present, the test methods and means used in the wire use industry for wire insulation performance fault detection mainly include: visual inspection method, resistance method, voltage withstand test, etc. The above methods are applied to different scenarios, but they all have certain limitations.

[0003] 1) Visual inspection method: generally used when the insulation performance requirements for the wire are not high or when the insulation defects are obvious.

[0004] This method can only check whether there is obvious damage on the cable surface, and requires that the wire can be unfolded and unobstructed. It cannot detect hidden defects of the wire or possible insulation faults in the obstructed part, and the test accuracy is low.

[0005] 2) Resistance method: apply 500V or 1000V DC to the wire and measure the insulation resistance of the wire, which is generally in the megohm level. The larger the insulation resistance value, the better the insulation performance of the wire.

[0006] This method requires the use of high-voltage direct current, which is somewhat dangerous. It can only check whether the insulation performance of the wire meets the requirements, but cannot locate the insulation fault point.

[0007] 3) Withstand voltage test method: apply 2 times the rated voltage plus 1000V high voltage AC to the conductor, or apply high voltage according to the withstand voltage standard of the conductor, and detect the leakage current of the conductor, which is generally mA level. The smaller the current, the better the insulation properties of the conductor.

[0008] This method requires the use of high-voltage alternating current, which is somewhat dangerous. If the wire is damaged, it may cause damage to other equipment or personal injury. At the same time, this method can only check whether there are defects in the insulation performance of the wire, and cannot locate the defect.

[0009] In order to solve the problem of detecting and locating hidden defects in wire insulation, it is necessary to design a safer, more reliable and more efficient wire insulation defect detection and locating device. Summary of the invention

[0010] The purpose of the present invention is to improve the shortcomings of existing testing methods and provide a wire insulation defect detection and positioning device to solve the technical problems of low testing accuracy, inconvenient testing, low efficiency and inability to locate defects in existing testing methods.

[0011] The technical solution of the present invention is:

[0012] A conductor insulation defect detection and positioning device, comprising a signal generating device [1], a signal acquisition and analysis device [2] and a test adapter cable [3];

[0013] The signal generating device [1] is used to provide a high-frequency signal of a certain amplitude to the conductor under test; the signal acquisition and analysis device [2] has the functions of wired acquisition and signal processing and analysis of high-frequency signals, and is used to acquire incident high-frequency signals and reflected high-frequency signals in the conductor, and process, display and analyze the collected incident high-frequency signals and reflected high-frequency signals; the test adapter cable [3] connects the signal generating device [1] and the conductor under test [6], and is also connected to the signal acquisition and analysis device [2].

[0014] The characteristic is that, in order to reduce the influence of the adapter cable [3] on the waveform, the adapter cable [3] should use a wire of the same quality as the measured wire [6].

[0015] The invention is characterized in that the incident high-frequency signal generated by the signal generating device [1] is used as the incident wave [4]; when the impedance in the measured conductor [6] changes, the reflected high-frequency signal generated by the incident wave [4] at the changed position is used as the reflected wave [5].

[0016] The invention is characterized in that the signal acquisition and analysis device [2] is connected to the acquisition point on the test adapter cable [3], and the incident wave [4] and the reflected wave [5] are simultaneously acquired at the acquisition point.

[0017] The characteristic is that the calculation formula of the wire insulation defect position is:

[0018]

[0019] Where, L: the distance between the impedance change point and the incident signal collection point;

[0020] V: The speed at which the signal propagates in the wire;

[0021] △T: The time interval between the reflected signal and the incident signal.

[0022] The characteristic is that the time interval △T between the reflected signal and the incident signal is smaller than the period of the incident wave [4].

[0023] The invention is characterized in that the signal generating device [1] adopts an Agilent 34401A arbitrary function generator or an arbitrary waveform generator module NI-PCI-5406.

[0024] The invention is characterized in that the signal acquisition and analysis device [2] adopts an Agilent 54832B multi-function oscilloscope.

[0025] The advantages of the present invention are:

[0026] According to the practical difficulties encountered in the current wire insulation test process, the present invention proposes a wire insulation defect detection and positioning device, which has the following beneficial effects:

[0027] 1) The test is highly safe. The wire insulation defect detection and positioning device proposed in the present invention does not involve high-voltage direct current and alternating current, and uses high-frequency signals that do not have load-carrying capacity, which will not cause harm to equipment and personnel.

[0028] 2) It can detect hidden insulation defects and locate them. The device is based on the principle of time domain reflection method. By sending pulses or step signals to the medium under test, when the medium impedance changes, a reflected wave will be generated, and the remaining electromagnetic energy will continue to propagate in the medium. The impedance change is calculated by comparing the incident wave amplitude and the reflected wave amplitude, and the position information of the impedance change is obtained based on the time difference. As long as there are defects in the wire, it can be characterized by this device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the principle of the present invention

[0030] Figure 2 RG-58 coaxial cable insulation fault test effect diagram DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0032] like Figure 1 As shown, a wire insulation defect detection and positioning device of the present invention comprises a signal generating device [1], a signal acquisition and analysis device [2] and a test adapter cable [3]; wherein the signal generating device [1] is used to provide a high-frequency signal of a certain amplitude to the wire under test; the signal acquisition and analysis device [2] has the functions of wired acquisition of high-frequency signals and signal processing and analysis, and is used to collect incident high-frequency signals and reflected high-frequency signals in the wire, and process, display and analyze the collected incident high-frequency signals and reflected high-frequency signals; the test adapter cable [3] connects the signal generating device [1] and the wire under test [6], and is also connected to the signal acquisition and analysis device [2].

[0033] It is important to note that:

[0034] 1) A signal generating device [1] is used to provide a high-frequency signal of a certain amplitude to the conductor under test, such as an Agilent 34401A arbitrary function generator or an arbitrary waveform generator module NI-PCI-5406.

[0035] 2) The signal acquisition and analysis device [2] has the functions of high-frequency signal wired acquisition and signal processing and analysis, and is used to acquire the incident high-frequency signal and the reflected high-frequency signal in the wire, and process, display and analyze the received signal, for example: Agilent54832B multi-function oscilloscope.

[0036] 3) The test adapter cable [3] is connected to the signal generating device [1] and the measured wire [6], and is also connected to the signal acquisition and analysis device [2]. In order to reduce the influence of the adapter cable on the waveform, the length of the test cable should be as short as possible and the same wire as the measured cable should be used.

[0037] 4) The incident wave [4] is a test signal generated by the signal generating device [1].

[0038] 5) The reflected wave [5] is the reflection signal generated by the incident wave [4] at the changed position when the impedance in the conductor changes.

[0039] 6) The conductor under test [7] is the test object.

[0040] 7) The conductor insulation defect detection and positioning device is based on the principle of time domain reflection method. By sending a pulse or step signal to the medium under test, when the medium impedance changes, a reflected wave will be generated, and the remaining electromagnetic energy will continue to propagate in the medium. The impedance change is calculated by comparing the incident wave amplitude and the reflected wave amplitude, and the position information of the impedance change is obtained based on the time difference.

[0041] The impedance change positioning formula is:

[0042]

[0043] Where, L: the distance between the impedance change point and the incident signal collection point;

[0044] V: The speed at which the signal propagates in the wire;

[0045] △T: The time interval between the reflected signal and the incident signal.

[0046] Example 1: The device is used to test the insulation fault of RG-58 coaxial cable, and the effect is as follows Figure 2 .

[0047] First, take a section of the measured wire with a length of L0, and calculate the speed V0 of the signal propagating in the wire according to the length of the measured wire and the transmission time T0 of the incident signal in this section of the wire:

[0048] Calculate the transmission speed of the incident signal in the wire

[0049]

[0050] In the formula, L0 is the measured guide length;

[0051] T0 is the time it takes for the incident signal to propagate in the measured wire of length L0;

[0052] V0 is the speed at which the incident signal is transmitted in the conductor being measured.

[0053] Calculation of each insulation position of the measured conductor:

[0054]

[0055] Where, L1, L2, L3: the distance between the impedance change position and the incident signal input point;

[0056] △T1: the time interval between the first reflected signal and the incident signal;

[0057] △T2: the time interval between the second reflected signal and the incident signal;

[0058] △T3: The time interval between the third reflected signal and the incident signal.

[0059] According to the above formula, the insulation defect position 1, the insulation defect position 2 and the insulation defect position 3 of the conductor can be calculated.

Claims

1. A wire insulation defect detection and positioning device, comprising a signal generating device [1], a signal acquisition and analysis device [2] and a test adapter cable [3]; in, The signal generating device [1] is used to provide a high-frequency signal of a certain amplitude to the conductor under test; the signal acquisition and analysis device [2] has the functions of wired acquisition and signal processing and analysis of high-frequency signals, and is used to acquire the incident high-frequency signal and the reflected high-frequency signal in the conductor, and process, display and analyze the collected incident high-frequency signal and the reflected high-frequency signal; the test adapter cable [3] is connected to the signal generating device [1] and the conductor under test [6], and is also connected to the signal acquisition and analysis device [2].

2. A wire insulation defect detection and positioning device as claimed in claim 1, characterized in that: In order to reduce the influence of the adapter cable [3] on the waveform, the adapter cable [3] should use a conductor of the same quality as the conductor [6] being measured.

3. A wire insulation defect detection and positioning device as claimed in claim 2, characterized in that: The incident high-frequency signal generated by the signal generating device [1] is referred to as the incident wave [4]; when the impedance in the measured conductor [6] changes, the reflected high-frequency signal generated by the incident wave [4] at the changed position is referred to as the reflected wave [5].

4. A wire insulation defect detection and positioning device as claimed in claim 3, characterized in that: The signal acquisition and analysis device [2] is connected to the acquisition point on the test adapter cable [3], and simultaneously acquires the incident wave [4] and the reflected wave [5] at the acquisition point.

5. A wire insulation defect detection and positioning device as claimed in claim 4, characterized in that: The calculation formula for the location of wire insulation defects is: Where, L: the distance between the impedance change point and the incident signal collection point; V: The speed at which the signal propagates in the wire; △T: The time interval between the reflected signal and the incident signal.

6. A wire insulation defect detection and positioning device as claimed in claim 5, characterized in that: The time interval △T between the reflected signal and the incident signal is less than the period of the incident wave [4].

7. A wire insulation defect detection and positioning device as claimed in claim 6, characterized in that: The signal generating device [1] uses an Agilent 34401A arbitrary function generator or an arbitrary waveform generator module NI-PCI-5406.

8. A wire insulation defect detection and positioning device as claimed in claim 7, characterized in that: The signal acquisition and analysis device [2] uses an Agilent 54832B multi-function oscilloscope.

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