Railway cable insulation detection device

Abstract

The utility model discloses a railway cable insulation detection device. The device comprises a high-voltage direct-current power supply, a resistance bridge, a first resistor and a first voltage measuring unit, the resistance bridge comprises a second resistor and a third resistor which are connected in series; the first resistor and the cable to be tested are connected in series to form another resistance bridge; the first end of the high-voltage direct-current power supply is electrically connected with the first end of the cable to be detected and the first end of the second resistor; the second end of the third resistor and the second end of the first resistor are electrically connected with the second end of the high-voltage direct-current power supply; the first end of the first voltage measuring unit is electrically connected with the second end of the second resistor and the first end of the third resistor; the second end of the first voltage measuring unit is electrically connected with the second end of the cable to be measured and the first end of the first resistor. According to the scheme, the insulation resistance between the railway cable and the ground wire is detected.

Description

Technical Field

[0001] This utility model relates to the field of railway cable technology, and in particular to a railway cable insulation testing device. Background Technology

[0002] The key to realizing railway modernization is electrification and automation. Railway cables are an important carrier for communication signal transmission, and ensuring good insulation performance of cables to ground is a crucial and fundamental aspect. For a medium-sized station, the area controlled by its control room includes not only the station yard but also a wider range of lines. The transmission of power and signals between these lines relies on thousands of cables placed in underground trenches. Therefore, it is essential to test the insulation performance of these cables to ground. Since railway transportation is uninterrupted, cable insulation testing can only be carried out when the cables are energized. For the monitoring system, in addition to the requirements for monitoring accuracy, there are also special requirements for the reliability and safety of the monitoring.

[0003] In current technologies, railway cable insulation testing relies on electromagnetic waveform data from multiple sub-cables within the target cable to determine whether the target cable is in an insulation fault state, without specifically determining the magnitude of the cable insulation resistance. Utility Model Content

[0004] This utility model provides a railway cable insulation testing device to detect the insulation resistance of railway cables.

[0005] To achieve the above objectives, this utility model provides a railway cable insulation testing device, which includes: a high-voltage DC power supply, a resistance bridge, a first resistor, and a first voltage measuring unit; the resistance bridge includes a second resistor and a third resistor connected in series; the first resistor and the cable under test are connected in series to form another resistance bridge;

[0006] The first end of the high-voltage DC power supply is electrically connected to the first end of the cable under test and the first end of the second resistor; the second end of the third resistor and the second end of the first resistor are both electrically connected to the second end of the high-voltage DC power supply; the first end of the first voltage measuring unit is electrically connected to the second end of the second resistor and the first end of the third resistor; the second end of the first voltage measuring unit is electrically connected to the ground wire of the cable under test and the first end of the first resistor.

[0007] Optionally, the device further includes a current-limiting resistor; the current-limiting resistor is connected in series between the first terminal of the high-voltage DC power supply and the first terminal of the second resistor.

[0008] Optionally, the output voltage U1 range of the high-voltage DC power supply satisfies: 498V≤U1≤505V.

[0009] Optionally, the device may also include: a low-voltage DC power supply, a fourth resistor, a fifth resistor, and a second voltage measurement unit;

[0010] The first terminal of the low-voltage DC power supply is electrically connected to the first terminal of the fourth resistor; the second terminal of the fourth resistor is connected to one end of the cable under test; the ground wire corresponding to the cable under test is electrically connected to the first terminal of the fifth resistor; the second voltage measuring unit is electrically connected in parallel to both ends of the fifth resistor; and the second terminal of the fifth resistor is electrically connected to the second terminal of the low-voltage DC power supply.

[0011] Optionally, the device further includes: an alarm unit, a test unit, and a jumper wire; the test unit includes a first test resistor and a second test resistor; the cable under test includes a first core wire and a second core wire;

[0012] The first end of the first test resistor is electrically connected to the first end of the first core wire; the second end of the first core wire is connected to the second end of the second core wire through the jumper wire; the first end of the second core wire is electrically connected to the second end of the second test resistor; the first end of the second test resistor is electrically connected to the first end of the first test resistor and receives a power signal.

[0013] The alarm unit is used to output an alarm signal when the insulation resistance between the cable under test and the ground wire reaches a preset resistance, so that the test unit outputs the power signal.

[0014] Optionally, the output voltage U2 of the low-voltage DC power supply satisfies: 45V≤U2≤55V.

[0015] In this embodiment of the invention, the first end of the high-voltage DC power supply is electrically connected to the first end of the cable under test and the first end of the second resistor; the second end of the third resistor and the second end of the first resistor are both electrically connected to the second end of the high-voltage DC power supply; the first end of the first voltage measuring unit is electrically connected to the second end of the second resistor and the first end of the third resistor; the second end of the first voltage measuring unit is electrically connected to the ground wire corresponding to the cable under test and the first end of the first resistor. Thus, by adjusting the third resistor to be the same as the first resistor using the Wheatstone bridge measurement principle, the first voltage measuring unit detects a voltage of 0. At this time, the insulation resistance between the railway cable and the ground wire is the same as the second resistor, thereby realizing the detection of the insulation resistance between the railway cable and the ground wire.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a railway cable insulation testing device provided in an embodiment of this utility model;

[0019] Figure 2 This is a schematic diagram of another railway cable insulation testing device provided in this embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of another railway cable insulation testing device provided in this embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the structure of an insulation fault location and detection unit provided in an embodiment of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] Figure 1 This is a schematic diagram of the structure of a railway cable insulation testing device provided in an embodiment of this utility model, as shown below. Figure 1As shown, the railway cable insulation testing device includes: a high-voltage DC power supply U1, a resistance bridge 01, a first resistor R1, and a first voltage measuring unit V1; the resistance bridge 01 includes a second resistor R2 and a third resistor R3 connected in series; the first resistor R1 and the cable under test are connected in series to form another resistance bridge; the first end of the high-voltage DC power supply U1 is electrically connected to the first end of the cable under test and the first end of the second resistor R2; the second end of the third resistor R3 and the second end of the first resistor R1 are both electrically connected to the second end of the high-voltage DC power supply U1; the first end of the first voltage measuring unit V1 is electrically connected to the second end of the second resistor R2 and the first end of the third resistor R3; the second end of the first voltage measuring unit V1 is electrically connected to the ground wire of the cable under test and the first end of the first resistor R1.

[0025] In this embodiment, the output voltage U1 of the high-voltage DC power supply can satisfy: 498V≤U1≤505V; the third resistor R3 and the first resistor R1 can be thin-film resistors with high adjustment accuracy; the second resistor R2 is a known fixed resistor; specifically, the insulation resistance R' between the cable under test and the ground wire is measured as follows: based on the Wheatstone bridge measurement principle, when the third resistor R3 is adjusted to be the same as the first resistor R1, the first voltage measurement unit V1 detects a voltage of 0. At this time, the insulation resistance between the railway cable and the ground wire is the same as the second resistor R2. Thus, the insulation resistance between the railway cable and the ground wire can be determined to be the second resistor R2. In this way, the railway cable insulation detection device realizes the detection of the insulation resistance between the railway cable and the ground wire.

[0026] When the measured insulation resistance R' between the railway cable and the ground wire meets the preset value, the railway cable can be considered to have an insulation fault; for example, when the measured insulation resistance R' between the railway cable and the ground wire is less than 3MΩ, the railway cable is determined to have an insulation fault.

[0027] Optionally, based on the above embodiments, Figure 2 This is a schematic diagram of another railway cable insulation testing device provided in this embodiment of the present invention, as shown below. Figure 2 As shown, the railway cable insulation testing device also includes a current-limiting resistor R0; the current-limiting resistor R0 is connected in series between the first terminal of the high-voltage DC power supply U1 and the first terminal of the second resistor R2. The current-limiting resistor R0 serves to limit the current, ensuring high reliability of the measured insulation resistance R' of the railway cable to ground.

[0028] Optionally, based on the above embodiments, the railway cable insulation testing device is further optimized, and an insulation resistance testing unit with the same function as the above-mentioned railway cable insulation testing device is also integrated into the railway cable insulation testing device; the insulation resistance testing unit can be mutually calibrated with the above-mentioned railway cable insulation testing device; Figure 3This is a schematic diagram of another railway cable insulation testing device provided in this embodiment of the present invention, as shown below. Figure 3 As shown, the railway cable insulation testing device also includes: a low-voltage DC power supply U2, a fourth resistor R4, a fifth resistor R5, and a second voltage measuring unit V2; the first end of the low-voltage DC power supply U2 is electrically connected to the first end of the fourth resistor R4; the second end of the fourth resistor R4 is connected to one end of the cable under test; the ground wire of the cable under test is electrically connected to the first end of the fifth resistor R5; the second voltage measuring unit V2 is electrically connected in parallel to both ends of the fifth resistor R5; and the second end of the fifth resistor R5 is electrically connected to the second end of the low-voltage DC power supply V2.

[0029] The output voltage U2 of the low-voltage DC power supply satisfies: 45V≤U2≤55V. This embodiment is specifically based on the principle of voltage divider. The circuit current can be determined using the second voltage measurement unit V2 and the fifth resistor R5. According to the voltage divider principle, the voltage between the railway cable and the ground wire can be determined, and based on this voltage and the circuit current, the insulation resistance R” between the railway cable and the ground wire can be determined. Thus, when the insulation resistance R” between the railway cable and the ground wire is consistent with the insulation resistance R' of the railway cable and the ground wire in the above embodiment, the insulation resistance between the railway cable and the ground wire can be determined to be R'. This completes further calibration and avoids errors in the output of the insulation resistance detection unit.

[0030] Optionally, based on the above embodiments, the railway cable insulation detection device can be further optimized. When the measured insulation resistance R' between the railway cable and the ground wire meets the preset value, the railway cable insulation can be considered to be faulty. In this embodiment, the insulation detection device can also perform the location detection of cable insulation faults, that is, the railway cable insulation detection device also integrates an insulation fault location detection unit. Figure 4 This is a schematic diagram of the structure of an insulation fault location and detection unit provided in an embodiment of this utility model; as shown. Figure 4 As shown, Figure 4 As shown, the insulation fault location detection unit includes: an alarm unit 10, a test unit 21, and a jumper wire 22; the test unit 21 includes a first test resistor R11 and a second test resistor R12; the cable under test includes a first core wire L1 and a second core wire L2.

[0031] The first end of the first test resistor R11 is electrically connected to the first end of the first core wire L1; the second end of the first core wire L1 is connected to the second end of the second core wire L2 through the jumper wire 32; the first end of the second core wire L2 is electrically connected to the second end of the second test resistor R12; the first end of the second test resistor R12 is electrically connected to the first end of the first test resistor R11 and receives a power signal; the alarm unit 10 is used to output an alarm signal so that the test unit 21 outputs a power signal when the insulation resistance R' between the cable under test and the ground wire reaches a preset resistance.

[0032] The cable under test includes a first core wire L1 and a second core wire L2; a jumper wire 22 is connected to the first core wire L1 and the second core wire L2; the resistance of the first test resistor R11 and the second test resistor R12 in the test unit 21 is fixed.

[0033] When the measured insulation resistance R' between the railway cable and the ground wire meets the preset value, the railway cable can be considered to have an insulation fault. The fault point can then be on the first core wire L1 or the second core wire L2. In this embodiment, it is assumed that the fault point is at a certain position A on the second core wire L2 (the second core wire can include part of the second core wire L2-Lx and part of the second core wire Lx). When the alarm unit 10 detects that the insulation resistance R' has reached the preset resistance, it outputs an alarm signal to cause the test unit 21 to output a power signal. At this time, the first test resistor R11, the first core wire L1, and part of the second core wire L2-Lx within the test unit 21 form a resistance bridge, while the second test unit R12 and other parts of the second core wire Lx form another resistance bridge. Based on the bridge method, it can be determined that:

[0034] R11 / R12=k(L11+L12-Lx) / kLx,

[0035] Where k is the resistivity coefficient; L11 represents the length of the first core wire L1; L12 represents the length of the second core wire L2; Lx is the distance from the test unit 21 to the insulation fault point A; thus, Lx = 2LR12 / (R11 + R12) is determined, where L = L11 = L12; thus, in this embodiment, the insulation detection device also completes the location detection of cable insulation faults.

[0036] It should be noted that this embodiment may also include a galvanometer I, the first end of which is electrically connected to the second end of the first test resistor R11; the second end of the galvanometer I is electrically connected to the second end of the second test resistor R12; if the first test resistor R11 and the second test resistor R12 are the same, the reading of the galvanometer I is 0; and if the first test resistor R11 and the second test resistor R12 are different, the reading of the galvanometer I is not 0.

[0037] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A railway cable insulation detection device, characterized by, include: A high-voltage DC power supply, a resistance bridge, a first resistor, and a first voltage measurement unit; the resistance bridge includes a second resistor and a third resistor connected in series; the first resistor and the cable under test are connected in series to form another resistance bridge; The first end of the high-voltage DC power supply is electrically connected to the first end of the cable under test and the first end of the second resistor; the second end of the third resistor and the second end of the first resistor are both electrically connected to the second end of the high-voltage DC power supply; the first end of the first voltage measuring unit is electrically connected to the second end of the second resistor and the first end of the third resistor; the second end of the first voltage measuring unit is electrically connected to the ground wire of the cable under test and the first end of the first resistor.

2. The railroad cable insulation detection apparatus of claim 1, wherein, Also includes: A current-limiting resistor; the current-limiting resistor is connected in series between the first terminal of the high-voltage DC power supply and the first terminal of the second resistor.

3. The railroad cable insulation detection apparatus of claim 1, wherein, The output voltage U1 of the high-voltage DC power supply satisfies: 498V≤U1≤505V.

4. The railroad cable insulation detection apparatus of claim 1, wherein Also includes: Low-voltage DC power supply, fourth resistor, fifth resistor and second voltage measurement unit; The first terminal of the low-voltage DC power supply is electrically connected to the first terminal of the fourth resistor; the second terminal of the fourth resistor is connected to one end of the cable under test; the ground wire corresponding to the cable under test is electrically connected to the first terminal of the fifth resistor; the second voltage measuring unit is electrically connected in parallel to both ends of the fifth resistor; and the second terminal of the fifth resistor is electrically connected to the second terminal of the low-voltage DC power supply.

5. The railroad cable insulation detection apparatus of claim 1, wherein, Also includes: An alarm unit, a test unit, and a jumper wire; the test unit includes a first test resistor and a second test resistor; the cable under test includes a first core wire and a second core wire. The first end of the first test resistor is electrically connected to the first end of the first core wire; the second end of the first core wire is connected to the second end of the second core wire through the jumper wire; the first end of the second core wire is electrically connected to the second end of the second test resistor; the first end of the second test resistor is electrically connected to the first end of the first test resistor and receives a power signal. The alarm unit is used to output an alarm signal when the insulation resistance between the cable under test and the ground wire reaches a preset resistance, so that the test unit outputs the power signal.

6. The railroad cable insulation detection apparatus of claim 4, wherein, The output voltage U2 of the low-voltage DC power supply satisfies: 45V≤U2≤55V.

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