Cable shielding grounding fault and temperature passive sensing monitoring module in switch cabinet

Abstract

The utility model provides a cable shielding grounding fault and temperature passive sensing monitoring module in a switch cabinet, which is characterized by comprising a current transformer used for sensing current on a cable shielding layer to generate an electric signal; the photoelectric converter comprises a power supply end, an input signal end and an output signal end, and the power supply end and the input signal end are electrically connected with the output end of the current transformer; one end of the optical fiber is connected with the output signal end; and the optical signal receiver is connected with the other end of the optical fiber. According to the utility model, real-time monitoring of the grounding fault of the cable shielding layer can be realized, and safe and reliable operation of the cable is guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to cable detection technical field especially relates to a switchgear internal cable shielding ground fault and temperature passive sensing monitoring module. BACKGROUND

[0002] At present, the shielding wire single-end grounding mode is adopted during the field installation of the medium voltage cable in the nuclear power plant, that is, the shielding layer of one end of the cable is grounded, and the other end is sealed in the cable joint and is suspended. With the extension of the cable operation time, the outer sheath of the cable is damaged due to extrusion, aging and other factors, and the shielding grounding fault will occur at the damaged part. At this time, the shielding layer of the running cable has a multi-point grounding fault.

[0003] When the medium voltage cable is normally operated, the metal shielding layer will generate an induced voltage. When the shielding layer has a multi-point grounding, an induced voltage difference will be generated, and the voltage difference will cause a shielding circulating current through the ground or the return flow. The occurrence of the circulating current causes the cable loss to heat, resulting in local high temperature, accelerating the aging of the main insulation, and inducing the cable to generate partial discharge, which causes a great safety hazard to the safe operation of the cable. When the running cable has a shielding layer multi-point grounding fault, the prior art cannot timely understand the fault information. Therefore, there is room for improvement. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the utility model is to provide a switchgear internal cable shielding grounding fault and temperature passive sensing monitoring module, which is used to solve the problem that the fault information cannot be understood in time when the running cable has a shielding layer multi-point grounding fault.

[0005] To achieve the above-mentioned purpose and other related purposes, the utility model provides a switchgear internal cable shielding grounding fault and temperature passive sensing monitoring module, which comprises:

[0006] A current transformer is used to generate an electric signal by sensing the current on the shielding layer of the cable.

[0007] An optical-electricity converter comprises a power supply end, an input signal end and an output signal end, and the power supply end, the input signal end and the output end of the current transformer are electrically connected.

[0008] An optical fiber is connected to one end of the output signal end.

[0009] An optical signal receiver is connected to the other end of the optical fiber.

[0010] In an embodiment of the utility model, the current transformer is a high-sensitivity current coupling sensor, and the high-sensitivity current coupling sensor is connected to the surface of the grounding wire of the shielding layer of the cable in a patch mode.

[0011] In an embodiment of the utility model, the current transformer further includes an insulator shell, and the insulator shell is connected to the grounding wire surface of the cable shielding layer.

[0012] In an embodiment of the utility model, the switch cabinet cable shielding grounding fault and temperature passive sensing monitoring module further includes a magnetic ring, and the magnetic ring is arranged on the connecting line between the current transformer and the photoelectric converter.

[0013] In an embodiment of the utility model, the magnetic ring is located on the side close to the current transformer.

[0014] In an embodiment of the utility model, the bandwidth frequency of the magnetic ring is 40Hz-60Hz.

[0015] In an embodiment of the utility model, the switch cabinet cable shielding grounding fault and temperature passive sensing monitoring module further includes:

[0016] a thermal resistance, located on the cable shielding layer;

[0017] a measurement circuit module, electrically connected to both ends of the thermal resistance, to measure the resistance value of the thermal resistance;

[0018] a control module, connected to the optical signal receiver and the measurement circuit module, to receive the optical signal of the optical signal receiver and control the measurement circuit module to measure the resistance value of the thermal resistance.

[0019] In an embodiment of the utility model, the current transformer and the photoelectric converter are jointly arranged in one installation shell, and the optical signal receiver, the measurement circuit module and the control module are jointly arranged in another installation shell.

[0020] In an embodiment of the utility model, the thermal resistance is arranged on the current transformer.

[0021] In an embodiment of the utility model, the thermal resistance is separated from the current transformer.

[0022] As described above, the switch cabinet cable shielding grounding fault and temperature passive sensing monitoring module of the utility model realizes real-time monitoring of the cable shielding layer grounding fault, and guarantees safe and reliable operation of the cable line. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the cable line in the prior art.

[0024] Figure 2 It is a schematic diagram of normal power supply of the cable line in the prior art.

[0025] Figure 3 A schematic diagram of a cable line power-on ground fault of a shielding layer in the prior art.

[0026] Figure 4 A structural block diagram of a monitoring device for a cable shielding layer ground fault under normal cable line power-on according to an embodiment of the present utility model.

[0027] Figure 5 A structural block diagram of a monitoring device for a cable shielding layer ground fault under cable line power-on ground fault of a shielding layer according to an embodiment of the present utility model.

[0028] Figure 6 A schematic diagram of a connection between a cable shielding layer and a current transformer under cable line power-on ground fault of a shielding layer according to an embodiment of the present utility model.

[0029] Reference signs: 10, cable line; 100, conductor; 101, high-voltage end; 110, insulation layer; 120, semiconductor layer; 130, cable shielding layer; 131, grounding wire; 140, outer sheath layer; 20, fault point; 30, current; 40, current transformer; 400, mounting shell; 50, photoelectric converter; 60, optical fiber; 70, magnetic ring; 80, optical signal receiver. DETAILED DESCRIPTION

[0030] The embodiments of the present utility model are described below through specific concrete examples, and those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in the present specification. The present utility model can also be implemented or applied through other different concrete embodiments, and each detail in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner, and the diagrams only show the components related to the present utility model without drawing the number, shape and size of the components in actual implementation, and the type, number and ratio of each component in actual implementation can be changed arbitrarily, and the component layout type can also be more complex.

[0032] In the following description, a large number of details are discussed to provide a more thorough explanation of the embodiments of the present utility model, however, it is obvious to those skilled in the art that the embodiments of the present utility model can be implemented without these specific details, and in other embodiments, the known structures and devices are shown in the form of block diagrams instead of details to avoid making the embodiments of the present utility model difficult to understand.

[0033] The utility model provides a kind of cable shielding ground fault and temperature passive sensing monitoring module in switchgear, it can be applied to nuclear power plant cable detection technical field, for example is nuclear power plant medium voltage shielding layer multipoint grounding fault field.The utility model converts the current signal on shielding layer into voltage signal under the condition of shielding layer grounding fault when cable is energized, then voltage signal is converted into optical signal, to prevent the interference of other electric signals outside to cable shielding layer, play the role of safe isolation.The following is described in detail by specific embodiment.

[0034] Please refer to Figure 4 、 Figure 5 And Figure 6 In an embodiment of the utility model, a kind of cable shielding ground fault and temperature passive sensing monitoring module in switchgear can include current transformer 40, photoelectric converter 50, optical fiber 60 and optical signal receiver 80.

[0035] Please refer to Figure 4 、 Figure 5 And Figure 6 In an embodiment of the utility model, current transformer 40 can be located on the surface of the grounding wire 131 of cable shielding layer 130, and current transformer 40 can generate electric signal by inducting the current on cable shielding layer 130.

[0036] Specifically, to facilitate the more detailed description of cable line 10 and cable shielding layer 130 in the following, the specific structure of cable line 10 can be introduced.As shown in Figure 1 Cable line 10 is conductor 100, insulating layer 110, semiconductor layer 120, cable shielding layer 130, outer sheath layer 140 from inside to outside, and cable shielding layer 130 is connected with grounding wire 131.

[0037] Please refer to Figure 4 、 Figure 5 And Figure 6 In an embodiment of the utility model, photoelectric converter 50 is also called optical coupler or opto-isolator, and is used to provide electrical isolation while transmitting signals between two circuits.The main function of photoelectric converter 50 is to convert electric signal into optical signal, so as to realize signal transmission without direct electrical connection.

[0038] Specifically, photoelectric converter 50 can include power supply end, input signal end and output signal end, wherein the power supply end, input signal end of photoelectric converter 50 can be electrically connected with the output end of current transformer 40, and the output signal end of photoelectric converter 50 can be connected with optical fiber 50.

[0039] Please refer to Figure 4In an embodiment of the present application, when the cable 10 is working normally and no current flows in the cable shielding layer 130, no induced electric signal is generated on the current transformer 40. Since the power supply end and the input signal end of the photoelectric converter 50 are electrically connected to the output end of the current transformer 40, when no induced electric signal is generated on the current transformer 40, the photoelectric converter 50 has no power supply and electric signal excitation source, and the photoelectric converter 40 is in a passive state and has no signal output. In addition, since the output signal end of the photoelectric converter 40 is connected to the optical fiber, no external electric signal will interfere with the photoelectric converter 40.

[0040] Please refer to Figure 5 and Figure 6 In an embodiment of the present application, when the cable 10 is working normally, but a multi-point grounding fault occurs in the cable shielding layer 130, due to the existence of induced voltage, the induced voltage values of different points are not the same, and the cable shielding layer 130 made of metal will generate a voltage difference. The existence of the voltage difference causes a current to flow in the cable shielding layer 130, and the current transformer 40 senses the current to generate a corresponding electric signal.

[0041] Specifically, for the current transformer 40 to sense the current to generate a corresponding electric signal, on the one hand, the electric signal can be connected to the power supply end of the photoelectric converter 50 to supply power to the photoelectric converter 50, and the photoelectric converter 50 enters a working state under the external power supply. On the other hand, the electric signal can also be used as an input signal source of the photoelectric converter 50 to excite the photoelectric converter 50 to generate an optical signal, and the generated optical signal is outputted to the outside through the optical fiber 60. That is to say, when the optical signal receiver 80 collects the optical signal, it can be indicated that a multi-point grounding fault occurs in the cable shielding layer 130, and maintenance needs to be carried out in a timely manner.

[0042] Compared with Figure 1 , Figure 2 and Figure 3 the prior art, in the prior art, during the overhaul of the nuclear power plant unit, by disconnecting the connection between the cable shielding layer 130 and the ground, the insulation resistance between the cable shielding layer 130 and the ground is measured, and it can be determined whether the cable shielding layer 130 has a grounding fault. However, the measurement work is limited by the cable isolation state, and the time window is very tight, and the work cannot be carried out comprehensively. During the operation of the unit, it is impossible to measure the insulation resistance between the cable shielding layer 130 and the ground.

[0043] In the technical scheme of the embodiment, the state of the cable shielding layer 130 is monitored in real time without changing the state of the cable. When the cable outer sheath layer 140 is damaged and the cable shielding layer 130 is grounded at multiple points, the situation can be monitored in time, so as to guide the maintenance personnel to carry out maintenance work in time and ensure that the cable line 10 operates safely and reliably. The photoelectric converter 50 and the optical fiber 60 can convert and isolate optical signals, and can prevent external electrical signals from affecting the cable shielding layer 130, thereby playing a safe isolation role.

[0044] Please refer to Figure 4 、 Figure 5 and Figure 6 In an embodiment of the utility model, the cable line 10 is a passive module in a normal state, and no external power supply is introduced, so that no external electrical signal is introduced to the cable line 10 during normal operation. The current transformer 40, the photoelectric converter 50 and the optical fiber 60 in the embodiment are all passive high-safety module devices, and can be applied to a nuclear power plant high-safety and reliable requirement place, such as a safety important and sensitive cable line 10 in a nuclear island of a nuclear power plant.

[0045] When the cable shielding layer 130 is grounded at multiple points, the current on the cable shielding layer 130 will induce a voltage signal by the current transformer 40, and the voltage signal makes the photoelectric converter 50 enter a working state. The photoelectric converter 50 converts the electrical signal into an optical signal and outputs the signal externally, and plays a physical isolation role, effectively prevents and inhibits the influence of external electrical signals on the current transformer 40 and the cable shielding layer 130, and also plays a high-safety and reliable role.

[0046] Please refer to Figure 4 、 Figure 5 and Figure 6 In an embodiment of the utility model, the current transformer 40 is a high-sensitivity current coupling sensor, and the high-sensitivity current coupling sensor is connected to the surface of the grounding wire 131 of the cable shielding layer 130 in a patch mode. The current transformer 40 includes an insulator shell connected to the surface of the grounding wire 131 of the cable shielding layer 130. The insulator shell of the current transformer 40 can be made of ethylene propylene rubber (EPR), and plays an insulating role without affecting the electrical performance of the cable shielding layer 130.

[0047] Please refer to Figure 4 、 Figure 5 and Figure 6In an embodiment of the utility model, switchgear inside cable shielding ground fault and temperature passive sensing monitoring module still include magnetic ring 70, the connecting wire between current transformer 40 and photoelectric converter 50 is equipped with magnetic ring 70. Magnetic ring 70 is located on the side close to current transformer 40. The bandwidth frequency of magnetic ring 70 is 40Hz~60Hz.

[0048] Specifically, the bandwidth of magnetic ring 70 is 40~60Hz, and magnetic ring 70 shows low resistance to power frequency signals, which does not affect the high-sensitivity current sensor to induce the circulating current of the cable shielding layer 130 under the 50Hz power frequency operation of the cable line 10. When non-power frequency (high frequency or low frequency) or flash signals flow through, magnetic ring 70 shows high resistance, which is equivalent to an open circuit, and can shield false actions caused by external interference, thereby improving reliability.

[0049] In an embodiment of the utility model, switchgear inside cable shielding ground fault and temperature passive sensing monitoring module still include thermal resistance, measurement circuit module and control module.

[0050] Specifically, the thermal resistance is a common temperature sensor that measures temperature by using the characteristic that the resistance of metal changes with temperature. The thermal resistance can be a platinum thermal resistance, such as a PT100 thermal resistance. The thermal resistance can be located on the cable shielding layer. The measurement circuit module can be electrically connected to both ends of the thermal resistance to measure the resistance value of the thermal resistance, wherein the measurement circuit module can be an active circuit. The control module is electrically connected to the optical signal receiver 80 and the measurement circuit module to receive the optical signal of the optical signal receiver 80 and control the measurement circuit module to measure the resistance value of the thermal resistance.

[0051] Specifically, when the cable shielding layer 130 has a multi-point grounding fault, the current on the cable shielding layer 130 will be induced by the current transformer 40 to generate an electrical signal, which causes the photoelectric converter 50 to enter a working state. The photoelectric converter 50 converts the electrical signal into an optical signal and outputs the optical signal externally through the optical fiber 60. After the optical signal receiver 80 receives the optical signal transmitted by the optical fiber 60, the control module can control the measurement circuit module to measure the resistance value of the thermal resistance, and analyze the temperature change on the cable shielding layer 130 through the temperature signal collected by the thermal resistance, to further determine the grounding fault of the cable shielding layer 130.

[0052] By measuring the resistance value of the thermal resistance, the temperature of the cable shielding layer 130 can be indirectly collected, thereby achieving double confirmation of the fault state of the cable shielding layer 130, preventing false actions caused by flash or noise, and improving reliability.

[0053] Please refer to Figure 5 and Figure 6In an embodiment of the utility model, current transformer 40, photoelectric converter 50 are commonly arranged in one installation shell 400, optical signal receiver 80, measurement circuit module and control module are commonly arranged in another installation shell.

[0054] In an embodiment of the utility model, thermal resistance, current transformer 40 are separated, current transformer 40 is located on the surface of ground wire 131 of cable shielding layer 130, and thermal resistance is located on the cable shielding layer.

[0055] In an embodiment of the utility model, thermal resistance is arranged on current transformer 40, current transformer 40 is located on the surface of ground wire 131 of cable shielding layer 130, and thermal resistance is located on the cable shielding layer.

[0056] Specifically, current transformer 40 is installed in the patch mode, without changing the medium voltage cable wiring mode in nuclear power field, greatly facilitates the installation of current transformer 40 under the mode of unit non-stop and cable uninterrupted power supply.Magnetic ring 70 improves the accuracy of power frequency signal acquisition and the suppression of interference signals, and photoelectric converter 50 and optical fiber 60 improve the physical isolation performance

[0057] In summary, the utility model discloses a kind of cable shielding ground fault and temperature passive sensing monitoring module in switch cabinet, realize the real-time monitoring of cable shielding layer ground fault, guarantee cable line safe and reliable operation.So, the utility model effectively overcomes the shortcomings in the prior art and has high industrial utilization value.

[0058] The above embodiment is only illustrative of the principle and effect of the utility model, and is not used to limit the utility model.Anyone skilled in the art can modify or change the above embodiment without departing from the spirit and scope of the utility model.Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the utility model should be covered by the claims of the utility model.

Claims

1. A module for monitoring cable shield ground fault and temperature passively in a switchgear, characterized by, The application relates to a cable shielding layer ground fault and temperature passive sensing monitoring module. The cable shielding layer ground fault and temperature passive sensing monitoring module comprises a current transformer, an optical-electricity converter, an optical fiber and an optical signal receiver. The current transformer is a high-sensitivity current coupling sensor which is connected to the surface of the ground wire of the cable shielding layer in a patch mode. The current transformer further comprises an insulator shell which is connected to the surface of the ground wire of the cable shielding layer. The cable shielding layer ground fault and temperature passive sensing monitoring module further comprises a magnetic ring which is arranged on the connecting line between the current transformer and the optical-electricity converter. The magnetic ring is arranged on the side close to the current transformer.

2. The module for monitoring the cable shielding ground fault and temperature in the switchgear according to claim 1, characterized in that, The bandwidth frequency of the magnetic ring is 40-60 Hz.

3. A module for monitoring cable shield ground fault and temperature in a switchgear according to claim 2, characterized in that, The cable shielding layer ground fault and temperature passive sensing monitoring module further comprises a thermal resistance which is arranged on the cable shielding layer, a measuring circuit module which is electrically connected to the two ends of the thermal resistance to measure the resistance value of the thermal resistance, and a control module which is connected to the optical signal receiver and the measuring circuit module to receive the optical signal of the optical signal receiver and control the measuring circuit module to measure the resistance value of the thermal resistance.

4. The module for monitoring the cable shielding ground fault and temperature in the switchgear according to claim 1, characterized in that, The current transformer and the optical-electricity converter are arranged in one installation shell, and the optical signal receiver, the measuring circuit module and the control module are arranged in another installation shell.

5. A module for monitoring cable shield ground fault and temperature in a switchgear according to claim 4, characterized in that, The thermal resistance is arranged on the current transformer.

6. A module for monitoring cable shield ground fault and temperature in a switchgear according to claim 4, characterized in that, The thermal resistance is separated from the current transformer.

7. A module for monitoring cable shield ground fault and temperature in a switchgear according to claim 1, characterized in that, ​ ​ ​ ​ 8. A module for monitoring cable shield ground fault and temperature in a switchgear according to claim 7, characterized in that, ​ 9. A module for monitoring cable shield ground fault and temperature in a switchgear according to claim 7, characterized in that, ​ 10. The module for monitoring the cable shielding ground fault and temperature in a switchgear according to claim 7, characterized in that, ​

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