CN207780157U - Direct current cables test terminal - Google Patents
Direct current cables test terminal Download PDFInfo
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- CN207780157U CN207780157U CN201721768545.2U CN201721768545U CN207780157U CN 207780157 U CN207780157 U CN 207780157U CN 201721768545 U CN201721768545 U CN 201721768545U CN 207780157 U CN207780157 U CN 207780157U
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- cable
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- insulating cylinder
- direct current
- water
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- 238000012360 testing method Methods 0.000 title claims abstract description 107
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 61
- 230000005684 electric field Effects 0.000 claims abstract description 24
- 238000009413 insulation Methods 0.000 claims abstract description 18
- 239000007789 gas Substances 0.000 claims description 18
- 238000002955 isolation Methods 0.000 claims description 13
- 238000007789 sealing Methods 0.000 claims description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000002347 injection Methods 0.000 claims description 4
- 239000007924 injection Substances 0.000 claims description 4
- 229920002367 Polyisobutene Polymers 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 229920002545 silicone oil Polymers 0.000 claims description 3
- 239000000945 filler Substances 0.000 abstract 1
- 239000004519 grease Substances 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 239000004593 Epoxy Substances 0.000 description 3
- 239000004020 conductor Substances 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000002242 deionisation method Methods 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 238000000265 homogenisation Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
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- Cable Accessories (AREA)
- Testing Relating To Insulation (AREA)
Abstract
The utility model provides a kind of direct current cables test terminal, including：Insulating cylinder, two grading shields, test cable and conductive isolating device.Wherein, two grading shields are separately positioned on the upper and lower ends on the outside of insulating cylinder, to be homogenized the external electric field of insulating cylinder；Test cable is sheathed on the inside of insulating cylinder in an axial direction；Conductive isolating device is closely sheathed between test cable and insulating cylinder, the region between test cable and insulating cylinder is separated into first dielectric first filled cavity of filling and fills the electric field of second dielectric second filled cavity and homogenizing the first filled cavity and the second filled cavity interface.The utility model forms different dielectric filler chambers by conductive isolating device in insulating cylinder, to form the insulation environment of half oily half water or half gas, half water, and it is distributed by adjusting the proportioning of grease to be homogenized test terminal inner electric field and outer electric field, and leakage current can be effectively reduced, while improving insulating cylinder and the edge flashing voltage on test cable surface.
Description
Technical Field
The utility model relates to a cable termination technical field particularly, relates to a direct current cable test terminal.
Background
The alternating current cable can use the water terminal as a test terminal and be recycled, the electric field distribution of the direct current cable is related to the conductivity, the pure water terminal can generate larger leakage current, and the output current of most of the existing direct current test equipment is smaller and can not meet the requirement. Therefore, most of the direct current cable tests are matched with formal direct current cable terminals for testing at present, but the formal direct current cable terminals are expensive and cannot be recycled, and at present, capacitor voltage-sharing or voltage-sharing ring voltage-sharing devices are developed and adopted at home, so that the field intensity distribution is structurally improved, the interior surface flashover is avoided, but the structure is complex and the assembly is difficult.
Disclosure of Invention
In view of this, the utility model provides a direct current cable test terminal aims at solving the great and complicated problem of installation of current direct current cable test terminal leakage current.
In one aspect, the utility model provides a direct current cable test terminal, include: the test device comprises an insulating cylinder, two voltage-sharing covers, a test cable and a conductive isolation device; the two voltage-sharing covers are respectively arranged at the upper end and the lower end of the outer side of the insulating cylinder and used for sharing the external electric field of the insulating cylinder; the test cable is sleeved in the insulating cylinder along the axial direction; the conductive isolation device is sleeved between the test cable and the insulating cylinder and used for dividing the area between the test cable and the insulating cylinder into a first filling cavity filled with a first dielectric medium and a second filling cavity filled with a second dielectric medium and homogenizing the electric field of the interface of the first filling cavity and the second filling cavity.
Further, in the above dc cable test terminal, the conductive isolation device is an interface cone or an annular sealing structure.
Further, in the above dc cable test terminal, the filling surface of the second dielectric in the second filling cavity is located at a preset height above the fracture of the test cable insulation shielding layer.
Further, in the direct current cable test terminal, the preset height is 10cm-2 m.
Further, in the above dc cable test terminal, the first dielectric is one or both of insulating oil and gas; the second dielectric is water.
Further, in the dc cable test terminal, the insulating oil is at least one of silicone oil, transformer oil or polyisobutylene; the gas is air, nitrogen or SF6At least one of (1).
Further, in the above dc cable test terminal, the method further includes: and the water circulating device is used for conveying water to the second filling cavity.
Further, in the above dc cable test terminal, a water inlet and a water outlet for communicating with the water circulation device are provided on the first flanges at the bottom of the insulation cylinder and the test cable.
Furthermore, in the above dc cable test terminal, the insulating cylinder and the second flange at the top of the test cable are provided with an injection hole for injecting the first dielectric into the insulating cylinder.
Further, in the above dc cable test terminal, the conductive isolation device is made of a conductive rubber material.
Further, in the above dc cable test terminal, the insulation cylinder is mounted on the movable platform through a bracket.
Compared with the prior art, the beneficial effects of the utility model reside in that, the utility model provides a direct current cable test terminal has formed different dielectric filling cavities through electrically conductive isolating device in the insulating cylinder, in order to form half oil semi-water or half gas semi-water's insulating environment, the electric field that utilizes the high conductance characteristic of water to come homogenization cable shielding fracture department is concentrated, utilize gas or oily low conductivity to reduce leakage current, and come homogenization test terminal inside electric field intensity and outside edge electric field distribution through the ratio of adjustment profit, consequently, leakage current can be effectively reduced, the edgewise flashover voltage on insulating cylinder and test cable surface has been improved simultaneously. The interface cone is adopted to control the shape of the oil-water interface, so that the field intensity distribution at the interface can be optimized. Compared with the alternating current cable test terminal in the prior art, the alternating current cable test terminal is not completely filled with water, and the leakage current is reduced, so that the alternating current cable test terminal can meet the requirement of the existing direct current test equipment; compare in current pressure equalizing ring type's test terminal, it is more convenient to install.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a schematic structural diagram of a dc cable testing terminal provided in an embodiment of the present invention;
fig. 2 is a top view of an upper seal ring according to an embodiment of the present invention;
fig. 3 is a top view of a lower seal ring according to an embodiment of the present invention;
fig. 4 is a top view of an interface cone provided by an embodiment of the present invention;
fig. 5 is a top view of a seal ring according to an embodiment of the present invention;
FIG. 6 is a diagram of an electric field distribution along the shielding surface of a conductor inside a test cable when the volume ratio of gas to water provided by the embodiment of the present invention is 2.5: 1;
FIG. 7 is a field intensity distribution diagram of the insulation surface of the test cable with a volume ratio of gas to water of 2.5:1 according to the embodiment of the present invention;
fig. 8 is a field intensity distribution diagram of the external surface of the insulation tube when the volume ratio of the gas to the water is 2.5:1 according to the embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Referring to fig. 1, the utility model discloses dc cable test terminal includes: the test device comprises an insulating cylinder 1, two voltage-sharing covers 2, a test cable 3 and a conductive isolation device 4. Wherein, the two voltage-sharing covers 2 are respectively arranged at the upper end and the lower end of the outer side of the insulating cylinder 1 and are used for sharing the external electric field of the insulating cylinder 1; the test cable 3 is sleeved inside the insulating cylinder 1 along the axial direction; the conductive isolation device 4 is tightly sleeved between the test cable 3 and the insulation cylinder 1 and used for dividing the area between the test cable 3 and the insulation cylinder 1 into a first filling cavity 5 filled with a first dielectric medium a and a second filling cavity 6 filled with a second dielectric medium b and homogenizing the electric field at the interface of the first filling cavity 5 and the second filling cavity 6.
Specifically, the insulating cylinder 1 comprises a cylindrical sleeve and the insulating sheath insulating cylinder 1 coated outside the cylindrical sleeve is made of epoxy resin or organic glass, the height of the insulating cylinder can be selected according to specific conditions, and the insulating cylinder is not limited in the embodiment. For example, a 6m epoxy tube may be selected. Two voltage-sharing covers 2 are coaxially arranged at the head end and the tail end of the insulating cylinder 1 to share the external electric field.
The test cable 3 comprises a cable core and an insulation shielding layer coated outside the cable core. The cable core at one end of the test cable 3 is connected with the high-voltage lead through one of the two voltage-sharing covers 2, and the outer sheath at the other end of the test cable is connected with the other voltage-sharing cover 2 and is grounded. During the test, part of the outer sheath and part of the insulating shielding layer of the test cable 3 need to be stripped.
With reference to fig. 1-4, after the upper sealing ring 15 and the lower sealing ring 16 are sleeved on the test cable 3, the test cable 3 is sleeved into the insulating cylinder 1, the fastening connection between the first flange 8 and the second flange 13 and the insulating cylinder 1 can be realized at the top and the bottom of the insulating cylinder 1 through fastening bolts, and in order to ensure the sealing performance between the insulating cylinder 1 and the first flange 8 and the second flange 13, O-shaped sealing rings 17 are respectively arranged between the insulating cylinder 1 and the two flanges. The second flange 13 may be provided with an injection hole 9 for injecting the first dielectric into the insulating tube 1, and for example, the first dielectric may be filled before the test and sealed during the test.
With reference to fig. 1 and 5, the conductive isolation device 4 is an interface cone or an annular sealing structure, and the shape thereof can be selected according to actual conditions, for example, the inner wall of the interface cone can be flared, and the annular sealing structure can be an annular sealing plug, etc. The conductive spacer 4 may be made of a conductive rubber material, has good elasticity, and can seal the interface between the first filling chamber 5 and the second filling chamber 6 to prevent the two dielectrics from being mixed and dissolved through the interface gap, and homogenize the electric field at the interface between the first filling chamber 5 and the second filling chamber 6.
In specific implementation, the conductive isolation device 4 is sleeved at a preset position of the test cable 3, the preset position is determined according to the volume ratio of the first dielectric medium to the second dielectric medium set by the test, and generally, the position is 10cm-2m above the fracture of the insulation shielding layer of the test cable 3.
The first dielectric a is one or both of insulating oil or gas. That is, the first dielectric a may be insulating oil, gas, or a mixture of insulating oil and gas. Preferably, the insulating oil is at least one of silicone oil, transformer oil or polyisobutylene; the gas is air, nitrogen or SF6At least one of (1). The second dielectric b is water, preferably deionized water.
For better homogenizing the electric field, the volume ratio of the first dielectric medium a to the second dielectric medium b is (1-30): 1, preferably 2.5: 1.
In order to homogenize the electric field concentration at the cable shield break, the filling level of the second dielectric b in the second filling chamber 6 is located at a preset height above the break of the insulating shield of the test cable 3. The preset height can be 10cm-2m above the fracture of the insulating shielding layer of the test cable 3.
In this embodiment, the method further includes: water circulation means 7 for feeding water into the second filling chamber 6.
Specifically, the water circulation device 7 may be any one of the water circulation devices in the prior art, and for example, the water circulation device may include: a water tank, a water pump and a deionization device which are connected in sequence. The insulating cylinder 1 and a first flange 8 at the bottom of the test cable 3 are provided with a water inlet 10 and a water outlet 11 which are communicated with the water circulation device 7. A water pump in the water circulating device 7 is respectively communicated with the water inlet 10 and the water outlet 11 so as to convey the deionized water treated by the deionization device in the water tank into the second filling cavity 6 and circulate the deionized water therein to ensure that the whole cavity is filled.
Referring to fig. 1-2 again, the installation and testing process of the dc cable testing terminal in this embodiment is as follows: firstly, respectively installing two voltage-sharing covers 2 at two ends of an insulating cylinder 1, then peeling off part of an outer sheath and part of an insulating shielding layer of a test cable 3, installing a conductive isolation device 4 at a preset position on the test cable 3, inserting the test cable 3 into the insulating cylinder 1 after installing a lower sealing ring 16 on the test cable 3, realizing the fastening connection of the test cable 3 and the insulating cylinder 1 through an upper sealing ring 15, a first flange 8 and a second flange 13, and installing an O-shaped sealing ring 17 between the insulating cylinder 1 and the first flange 8 and the second flange 13; and finally, connecting the cable core at one end of the test cable 3 into a high-voltage lead through one of the voltage-sharing covers 2, and connecting the outer sheath at the other end of the test cable with the other voltage-sharing cover and grounding the same. Before the test, insulating oil, gas or a mixture of the insulating oil and the gas is filled into the first filling cavity 5 through the filling hole 9; after the test is started, the injection hole 9 is sealed, high pressure is applied to the pressure equalizing cover 2 connected with the second flange 13, and the pressure equalizing cover 2 connected with the first flange 8 is grounded.
FIGS. 6-8 show the area of a cable core of an epoxy tube having a height of 6m and a diameter of 50cm and a diameter of 3000mm2Insulation thickness of 30mm, conductor shielding insulation shielding thickness of 2mm, voltage of 925kV, cable shielding port distance of 1m from flange bottom, gas-water volume ratio of 2.5:1And electric field distribution on the cable conductor shielding surface, the cable insulation surface and the insulation cylinder surface of the cable is tested. In the figure, the 0 position is the bottom end of the second flange.
It can be seen that when the air-water volume ratio is about 2.5:1, i.e. the distance from the bottom of the conductive isolation device to the bottom of the flange is 1720mm, no electric field concentration occurs on the insulating surface of the test cable, the insulating interior of the test cable and the exterior of the epoxy cylinder at the interface of the insulating shielding fracture of the test cable and the bottom of the conductive isolation device, and the electric field distribution is relatively uniform.
The resistivity of pure water is 1-18 x 105Ω · m, related to the temperature purity of the water; the resistivity of air is 10 due to the difference in humidity and pressure8-1013Omega m, oil resistivity of 1011～1013Ω·m。
Assuming that pure water is filled in the insulating cylinder in the example of the present invention, the resistance of the whole water is R ═ ρ ═ l/s, l ═ 6m, s ═ pi ═ s (radius of the insulating cylinder)2Radius of the cable2)＝1837.8cm2The resistance R of water is 0.326-5.88M omega, and the leakage current I is 925 kV/R2.837-0.157A.
The same calculation method shows that when the volume ratio of air to water is 2.5:1, the leakage current is 3.95 multiplied by 10-4～10- 9A, when the volume ratio of oil to water is 2.5:1, the leakage current is 3.95 multiplied by 10-7～10-9A, the output current of the current direct current high-voltage generator is generally 10-2And class A, the leakage current of the pure water terminal is far larger than that of the gas, water or oil and water mixture terminal.
The direct current cable test terminal provided in the embodiment obviously forms different dielectric filling cavities in the insulating cylinder through the conductive isolation device, forms a semi-oil semi-water or semi-gas semi-water insulating environment by utilizing a layering principle caused by oil-water or oil-gas density difference, homogenizes the distribution of the electric field intensity inside the test terminal and the external surface electric field by adjusting the proportion of oil-water, can effectively reduce leakage current, and simultaneously improves the surface flashover voltage of the insulating cylinder and the surface of the test cable. The interface cone is adopted to control the shape of the oil-water interface, so that the field intensity distribution at the interface can be optimized. Compared with the alternating current cable test terminal in the prior art, the alternating current cable test terminal is not completely filled with water, so that the alternating current cable test terminal can meet the requirement of the existing direct current test equipment; compare in current pressure equalizing ring type's test terminal, it is more convenient to install.
It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. A DC cable test terminal, comprising: the test device comprises an insulating cylinder (1), two voltage-sharing covers (2), a test cable (3) and a conductive isolating device (4); wherein,
the two voltage-sharing covers (2) are respectively arranged at the upper end and the lower end of the outer side of the insulating cylinder (1) and are used for sharing the external electric field of the insulating cylinder (1);
the test cable (3) is sleeved in the insulating cylinder (1) along the axial direction;
the conductive isolation device (4) is sleeved between the test cable (3) and the insulating cylinder (1) and used for separating the area between the test cable (3) and the insulating cylinder (1) into a first filling cavity (5) filled with a first dielectric medium (a) and a second filling cavity (6) filled with a second dielectric medium (b) and homogenizing the electric field of the interface of the first filling cavity (5) and the second filling cavity (6).
2. The direct current cable test terminal according to claim 1, characterized in that the electrically conductive separator means (4) is an interface cone or an annular sealing structure.
3. The direct current cable test terminal according to claim 1 or 2, characterized in that the filling level of the second dielectric (b) in the second filling cavity (6) is located at a preset height above the break of the insulation shield of the test cable (3).
4. The DC cable testing terminal of claim 3, wherein the predetermined height is 10cm-2 m.
5. The dc cable testing terminal of claim 1, wherein the first dielectric (a) is one or both of an insulating oil or gas; the second dielectric (b) is water.
6. The direct current cable test terminal of claim 5, wherein the insulating oil is at least one of silicone oil, transformer oil, or polyisobutylene; the gas is air, nitrogen or SF6At least one of (1).
7. The DC cable testing terminal of claim 5, further comprising: water circulation means (7) for conveying water into said second filling chamber (6).
8. The direct current cable test terminal according to claim 7, characterized in that the insulating cylinder (1) and the first flange (8) at the bottom of the test cable (3) are provided with a water inlet (10) and a water outlet (11) for communicating with the water circulation device (7).
9. The direct current cable test terminal according to claim 1 or 2, characterized in that the insulation cylinder (1) and the second flange (13) at the top of the test cable (3) are provided with injection holes (9) for injecting a first dielectric into the insulation cylinder (1).
10. The direct current cable test terminal according to claim 1 or 2, characterized in that the insulation cylinder (1) is mounted on a moving platform (12) by means of a bracket (14).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721768545.2U CN207780157U (en) | 2017-12-18 | 2017-12-18 | Direct current cables test terminal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721768545.2U CN207780157U (en) | 2017-12-18 | 2017-12-18 | Direct current cables test terminal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN207780157U true CN207780157U (en) | 2018-08-28 |
Family
ID=63226357
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201721768545.2U Active CN207780157U (en) | 2017-12-18 | 2017-12-18 | Direct current cables test terminal |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN207780157U (en) |
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2017
- 2017-12-18 CN CN201721768545.2U patent/CN207780157U/en active Active
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