CN104931865B - A kind of Voltage Cable Lines Construction pressure test insulating boot and test method - Google Patents

Abstract

The invention relates to an insulating cover and a test method for a high-voltage cable line withstand voltage test. The insulating cover is installed at the high-voltage cable terminal pile head of the cable warehouse, and is used to place the cable terminal pile on the high-voltage cable line when the high-voltage cable line is subjected to a pressure test. The head is separated from the surrounding ground potential. The insulating cover is L-shaped and is divided into a socket part and a lead-out part. The socket part and the lead-out part are both cylindrical structures, and a metal conductor is arranged inside the L-shaped insulating cover. The socket part is directly socketed on the high-voltage cable terminal pile head, and the lead-out part is used to lead the potential of the cable terminal pile head out from the inside of the insulating cover to the outside of the cable warehouse. The insulating cover effectively separates the pile head of the cable terminal from the surrounding ground potential, and solves the problem of insufficient distance between the pile head of the cable terminal indoors and the surrounding ground potential when carrying out the withstand voltage test of the cable line in the warehouse of the new transformer and distribution station. , and the traditional method used is easy to cause damage to the cable body and the production of pungent gas.

Description

Insulation cover and test method for high-voltage cable line withstand voltage test

technical field

The invention relates to a power cable circuit, in particular to a high-voltage cable withstand voltage test, and in particular to an insulating cover and a test method for a high-voltage cable circuit withstand voltage test.

Background technique

Power cable lines are one of the main elements for the transmission and distribution of electrical energy in the grid. Power cable lines are widely used in substations, switch stations, central stations and other places with dense power lines, playing an important role that overhead lines cannot replace. State Grid Shanghai Jiading Power Supply Company is in charge of the operation and maintenance management business of 35kV and 10kV cable lines (hereinafter referred to as "high voltage cable lines") in Jiading District, Shanghai.

The withstand voltage test of cable lines is the most routine work in new cable line projects, power outage maintenance, and emergency repairs. The substations and distribution stations put into operation in the early stage are all open positions. The distance is plentiful. However, with the development of closed and miniaturized switch cabinets in substations and distribution stations, the storage space for the incoming and outgoing high-voltage cable lines is becoming more and more compact, which causes the cable lines to be damaged due to indoor cables before the new project is put into operation, after power outage maintenance, and after emergency repair. The distance between the terminal pile head and the surrounding ground potential is relatively close, which makes it difficult for the withstand voltage test to meet the requirements of actual work.

In order to solve the above problems, the traditional method is:

Method 1: For small-section cables (cable section ≤ 120mm ² ), use the flexibility of the cable body to pull the cable terminal pile head out of the position, as shown in Figure 1, so as to maintain a certain distance from the surrounding ground potential to meet the withstand voltage test requirements.

This method has slight damage to the cable body, and it is difficult to re-lap the cable terminal pile head due to the displacement of the cable.

Method 2, for cables with large cross-section (cable cross-section ≥ 240mm ² ), due to the strong flexibility of the cable body, method 1 cannot be implemented. Generally, an insulating blanket is used to separate the cable terminal pile head from the surrounding ground potential.

Due to the dirt on the surface of the insulation blanket and the insulation structure, the surface leakage current is relatively large, which may easily cause the leakage current value of the withstand voltage test to be too large, which cannot correctly reflect the leakage current value of the cable body, and when the withstand voltage test value is high, Produces a pungent gas.

Contents of the invention

The object of the present invention is to provide an insulating cover for withstand voltage test of high-voltage cable lines. The insulating cover is installed on the cable terminal pile head to effectively separate the cable terminal pile head from the surrounding ground potential, so as to solve the When carrying out the withstand voltage test of the cable line in the warehouse of the distribution station, in order to avoid the insufficient distance between the pile head of the indoor cable terminal and the surrounding ground potential, the problem that the withstand voltage test is difficult to meet the actual work requirements, and at the same time, to avoid the cable body due to the traditional method. Problems with damage and production of pungent gas.

In order to achieve the above object, the solution of the present invention is: an insulating cover for withstand voltage test of high-voltage cable lines. , shielding the pile head of the cable terminal, keeping a sufficient safe distance from the surrounding ground potential, the insulating cover is L-shaped, and the L-shaped insulating cover is divided into a socket part and a lead-out part, and the socket part and The lead-out parts are all cylindrical structures, the L-shaped insulating cover is provided with a metal conductor, one end of the metal conductor is used to connect the cable terminal pile head during the withstand voltage test, and the other end of the metal conductor is used as The lead-out end passes through the lead-out part to the outside of the insulating cover, and is used to connect the high-voltage lead wire during the withstand voltage test. The socket part is directly socketed on the high-voltage cable terminal pile head, and the lead-out part is used to connect the cable terminal pile head The potential is drawn from the inside of the insulating cover to the outside of the cable compartment.

According to the insulating cover for high-voltage cable line withstand voltage test of the present invention, the sleeve part and the lead-out part are both provided with shed structures to increase creepage distance along the surface.

According to the insulating cover for high-voltage cable line withstand voltage test of the present invention, the metal conductor and the cable terminal pile head are connected by a spring pressure piece.

According to the insulating cover for high-voltage cable line withstand voltage test of the present invention, the spring pressing piece can be rotated at a 90-degree angle.

According to the insulating cover for high-voltage cable line withstand voltage test of the present invention, the material of the metal conductor is copper.

According to the insulating cover for high-voltage cable line withstand voltage test of the present invention, the material of the insulating cover is polytetrafluoroethylene.

According to the insulating cover for withstand voltage test of high-voltage cable lines of the present invention, the terminal of the metal conductor is provided with a high-voltage lead wire connection hole.

According to the insulating cover for high-voltage cable line withstand voltage test of the present invention, the internal hollow length of the socket part of the 10kV high-voltage cable is at least 140 mm to 145 mm, and the internal hollow diameter of the socket part is at least 51 mm to 55 mm. The top insulation thickness of the part is at least 10mm-12mm, and the side insulation thickness of the sleeve part is at least 8mm-10mm.

According to the insulating cover for high-voltage cable line withstand voltage test of the present invention, the internal hollow length of the socket part of the 35kV high-voltage cable is at least 190 mm to 195 mm, and the internal hollow diameter of the socket part is at least 65 mm to 70 mm. The top insulation thickness of the part is at least 12mm-14mm, and the side insulation thickness of the sleeve part is at least 10mm-12mm.

The object of the present invention is also to provide a method for carrying out a withstand voltage test using the above-mentioned insulating cover. The method effectively separates the cable terminal pile head from the surrounding ground potential through the socket part of the insulating cover to solve the problem of When carrying out the withstand voltage test of the cable line in the warehouse of the new substation, in order to avoid the insufficient distance between the pile head of the indoor cable terminal and the surrounding ground potential, the withstand voltage test cannot meet the actual work requirements. Problems with damage to the cable body and generation of pungent gas.

In order to achieve the above object, the solution of the present invention is: a method for carrying out a withstand voltage test using the above-mentioned insulating cover. The phase cable terminal pile head covers the three-phase cable terminal pile head to keep a safe distance from the surrounding ground potential; at the same time, the potential of the cable terminal pile head is led from the inside of the insulation cover to the outside of the warehouse through the lead-out part of the insulation cover; Then, the high-voltage lead wire of the withstand voltage test is directly connected to the conductor drawn from the inside of the insulating cover, and the withstand voltage test is started.

The beneficial effect that the present invention reaches:

(1) The insulating cover of the present invention is installed on the pile head of the cable terminal, effectively shielding the pile head of the cable terminal, and keeping a safe distance from the surrounding ground potential, so as to avoid insufficient distance between the indoor cable terminal pile head and the surrounding ground potential during the withstand voltage test , making it difficult for the withstand voltage test to meet the actual work requirements;

(2) The insulation cover of the present invention is designed in an L shape, and is divided into a socket part and a lead-out part. The socket part is used to shield the cable terminal pile head, and the lead-out part is used to lead the potential of the cable terminal pile head from the inside of the insulation cover to the cable. The outer side of the position makes the withstand voltage test safer and more reliable, and the insulating cover of the present invention has a simple structure and is convenient to carry and install.

(3) The socket part and the lead-out part of the insulating cover of the present invention are designed with an umbrella group structure, which effectively ensures a safe distance;

(4) The metal conductive part inside the insulating cover of the present invention is connected with the cable terminal pile head by a spring pressure piece, which can ensure the effectiveness of the connection.

(5) The spring pressing piece of the present invention can be rotated at a 90-degree angle, which not only satisfies the parallel arrangement and connection of general three-phase cables, but also meets the vertical arrangement and connection of three-phase cables.

(6) The insulating cover of the present invention adopts polytetrafluoroethylene material, which has low cost and high AC breakdown strength.

(7) The size design of the insulating cover of the present invention can meet the use of pile heads of various cross-section cable terminals without damaging the silicone rubber insulation of the cable terminal itself.

Description of drawings

Fig. 1 is the installation position schematic diagram of insulating cover of the present invention;

Fig. 2 is a schematic structural view of the insulating cover of the present invention.

In the figure, 1 is the socket part of the insulating cover, 2 is the lead-out part of the insulating cover, 3 is the shed structure, 4 is the metal conductor, and 5 is the high-voltage lead wire connection hole.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention is mainly aimed at carrying out a cable withstand voltage test after a new project of a high-voltage cable line, power outage maintenance, and fault repair. The distance between the pile head of the cable terminal located in the compact cable warehouse and the surrounding ground potential is relatively close, resulting in the failure to meet the voltage value of the withstand voltage test. To meet the required problem, design an insulating cover for shielding the pile head of the cable terminal.

As shown in Figure 1, the insulation cover of the present invention is installed at the pile head of the high-voltage cable terminal in the cable warehouse, and is used to shield the pile head of the cable terminal when the high-voltage cable line is subjected to a voltage test, so that it can be kept sufficiently close to the surrounding ground potential. Safe distance, avoiding the insufficient distance between the pile head of the indoor cable terminal and the surrounding ground potential during the withstand voltage test, which makes it difficult for the withstand voltage test to meet the requirements of actual work.

As shown in Figure 2, the insulating cover of the present invention is L-shaped, and the L-shaped insulating cover is divided into a socket part 1 and a lead-out part 2, and the socket part and the lead-out part are both cylindrical structures, The inside of the sleeve part 1 and the lead-out part 2 are connected, and a metal conductor 4 is arranged inside the L-shaped insulating cover, and one end of the metal conductor 4 is used to connect the cable terminal pile head during the pressure test. The other end of the metal conductor 4 is used as the lead-out end to pass through the lead-out part to the outside of the insulating cover, and is used to connect the high-voltage lead wire during the withstand voltage test. The socket part 1 is directly socketed on the high-voltage cable terminal pile head. The lead-out part 2 is used to lead the potential of the cable terminal pile head out from the inside of the insulation cover to the outside of the cable warehouse. The shed structure 3 is provided on the socket part and the lead-out part of the insulating cover to increase the creepage distance along the surface and effectively ensure the safety distance.

When the insulating cover of the present invention is used for the withstand voltage test, when preparing to carry out the withstand voltage test, first, the socket parts of the three insulating covers are correspondingly socketed on the pile heads of the three-phase cable terminals, and the three-phase cable terminal The pile head is shielded to keep a safe enough distance from the surrounding ground potential; at the same time, the potential of the cable terminal pile head is led from the inside of the insulation cover to the outside of the warehouse through the lead-out part of the insulation cover; then, the high-voltage lead wire of the withstand voltage test is directly connected to the insulation cover Conductors drawn from inside are subjected to withstand voltage test. Wherein, the high-voltage lead is connected to the metal conductor 4 through the high-voltage lead connection hole 5 .

Embodiment one:

This embodiment 1 is aimed at the 10kV conventional cables of the high-voltage cable line, and its cross-sections are 70mm ² , 120mm ² , 240mm ² , and 400mm ² . Please refer to Table 1 for specific dimensions.

Table 1 High-voltage cable indoor 10KV cable terminal pile head size table

In this embodiment, comprehensively considering that the pile heads of cable terminals with various cross-sections can be used without damaging the silicone rubber insulation of the cable terminal itself, the internal hollow length of the sleeve part of the insulation cover of the 10kV high-voltage cable is at least 140 mm to 145 mm, in order to make the cable terminal pile The head can be installed with an insulating cover. The design diameter of the insulating cover should be slightly larger than the width of the largest pile head at the same voltage level. The internal hollow diameter of the insulating cover socket part of the 10kV high-voltage cable is at least 51mm to 55mm. The top insulation thickness of the socket part of the insulation cover is at least 10mm ~ 12mm, and the side insulation thickness of the socket part is at least 8mm ~ 10mm. This insulation thickness can meet the requirements of the specified withstand voltage test value and leave sufficient margin.

When carrying out the withstand voltage test, the high-voltage lead wires are drawn from the pile head of the indoor cable terminal. discharge phenomenon. Comparing conventional insulating materials in electrical industry applications from the perspectives of relative permittivity, AC breakdown strength, machinability and economy, this example uses polytetrafluoroethylene material as the insulating part material of the insulating cover, polytetrafluoroethylene Tetrafluoroethylene satisfies machinability, low cost, and high AC breakdown strength.

In this embodiment, copper material is selected as the material of the conductor inside the insulating cover. The characteristics of copper material are mainly large electrical conductivity, high mechanical strength, easy processing and corrosion resistance, and copper material is generally used as the core material of high-voltage power cables. Copper material is used as the material of the internal conductor, which can ensure that when the auxiliary electrode is connected to the cable core, the contact resistance is small and avoid the auxiliary electrode from being broken due to accidental conditions during actual use.

In this embodiment, the metal conductor and the cable terminal pile head are connected by a spring pressing piece, which can ensure the effectiveness of the connection. The spring pressing piece can be rotated by 90 degrees, which not only meets the general three-phase parallel arrangement connection , and can meet the three-phase vertical arrangement connection.

When the insulating cover of the present invention is used for the withstand voltage test, each phase terminal pile head of the three-phase cable is correspondingly provided with an insulating cover, and the three insulating covers simultaneously cover the cable terminal pile heads of the corresponding phase, and the cable terminal pile head and the The surrounding ground potential is isolated to keep a safe distance between the cable terminal pile head and the surrounding ground potential, and the potential of the cable terminal pile head is led from the inside of the insulation cover to the outside of the warehouse through the lead-out part, and the high-voltage lead wire of the withstand voltage test is directly connected to the inside of the insulation cover The lead-out end of the lead-out conductor is subjected to a withstand voltage test. The test process is safer and more reliable. The following table 2 is the test result table:

Table 2 10KV cable insulation cover test results table

The insulating cover of this embodiment has a small leakage current value, no breakdown, no creepage, no heat generation, etc. under the specified voltage value of the withstand voltage test, which meets the design requirements.

Embodiment two:

Compared with the first embodiment, the second embodiment differs only in the design size. The cross section of the 35kV conventional cable is 400mm ² and 630mm ² . See Table 3 for the specific size.

Table 3 High-voltage cable indoor 35KV cable terminal pile head size table

In this embodiment, comprehensively considering that the pile heads of cable terminals with various cross-sections can be used without damaging the silicone rubber insulation of the cable terminal itself, the internal hollow length of the sleeve part of the insulation cover of the 35kV high-voltage cable is at least 190 mm to 195 mm, in order to make the cable terminal pile The head can be installed with an insulating cover. The design diameter of the insulating cover should be slightly larger than the width of the largest pile head at the same voltage level. The internal hollow diameter of the insulating cover socket part of the 35kV high-voltage cable is at least 65mm to 70mm. The top insulation thickness of the socket part of the insulation cover is at least 12mm ~ 14mm, and the side insulation thickness of the socket part is at least 10mm ~ 12mm. This insulation thickness can meet the requirements of the specified withstand voltage test value and leave a sufficient margin.

The following table 4 is the test effect table of the 35KV high voltage cable insulation cover:

Table 4 35KV cable insulation cover test effect table

The insulating cover of this embodiment has a small leakage current value, no breakdown, no creepage, no heat generation, etc. under the specified voltage value of the withstand voltage test, which meets the design requirements.

Through the insulating cover for the withstand voltage test of 10kV and 35kV cable lines developed by the invention, the withstand voltage test of the cable lines can be carried out in a compact cable storage space, while avoiding the disadvantages of the traditional method. The insulating cover of the present invention is installed on the pile head of the cable terminal, effectively shields the pile head of the cable terminal, and keeps a safe distance from the surrounding ground potential, so as to avoid the insufficient distance between the indoor cable terminal pile head and the surrounding ground potential during the withstand voltage test, resulting in The pressure test is difficult to meet the actual work requirements. At the same time, the insulating cover of the present invention includes a socket part and a lead-out part, through which the potential of the cable terminal pile head is led out from the inside of the insulating cover to the outside of the cable storage space, making the withstand voltage test safer and more reliable.

Claims (10)

1. A kind of 1. Voltage Cable Lines Construction pressure test insulating boot, it is characterised in that：It is high that described insulating boot is arranged on cable bin At voltage cable terminal pile crown, for when Voltage Cable Lines Construction carries out pressure test, cable termination pile crown being covered, with week Exclosure current potential keeps safe enough distance, and described insulating boot is L-shaped insulating boot, and described L-shaped insulating boot is divided into socket part And extension, described socket part and extension are cylindrical structure, and being provided with metal in described L-shaped insulating boot leads Electric body, one end of the metallic conductor are used for connecting cable terminal pile crown during pressure test, the metallic conductor it is another End as exit by extension through outside insulating boot, for connecting high-voltage connection, described socket during pressure test Part is directly socketed on hv cable termination pile crown, and described extension is used for cable termination pile crown current potential from insulating boot Inside is led on the outside of cable bin.
2. 2. Voltage Cable Lines Construction pressure test insulating boot according to claim 1, it is characterised in that described socket part Divide and extension is provided with umbrella skirt construction, to increase along face creep age distance.
3. 3. Voltage Cable Lines Construction pressure test insulating boot according to claim 1, it is characterised in that described metal is led Electric body is connected with cable termination pile crown using spring pressuring plate.
4. 4. Voltage Cable Lines Construction pressure test insulating boot according to claim 3, it is characterised in that described spring pressure Piece can 90 degree of corner transpositions.
5. 5. Voltage Cable Lines Construction pressure test insulating boot according to claim 1, it is characterised in that described metal is led The material of electric body is copper.
6. 6. Voltage Cable Lines Construction pressure test insulating boot according to claim 1, it is characterised in that the insulating boot Material is polytetrafluoroethylene (PTFE).
7. 7. Voltage Cable Lines Construction pressure test insulating boot according to claim 1, it is characterised in that described metal is led The exit of electric body is provided with high-voltage connection and connects hole.
8. 8. Voltage Cable Lines Construction pressure test insulating boot according to claim 1, it is characterised in that 10kV high-tension cables Insulating boot socket part inside hollow out length be at least 140mm~145mm, the inside hollow out diameter for being socketed part is at least 51mm~55mm, the top insulation thickness for being socketed part are at least 10mm~12mm, are socketed the avris insulation thickness of part at least For 8mm~10mm.
9. 9. Voltage Cable Lines Construction pressure test insulating boot according to claim 1, it is characterised in that 35kV high-tension cables Insulating boot socket part inside hollow out length be at least 190mm~195mm, the inside hollow out diameter for being socketed part is at least 65mm~70mm, the top insulation thickness for being socketed part are at least 12mm~14mm, are socketed the avris insulation thickness of part at least For 10mm~12mm.
10. A kind of 10. method that insulating boot described in claim 1 is used for pressure test, it is characterised in that be ready for pressure-resistant examination When testing, first, the socket part of three insulating boots is correspondingly sleeved on threephase cable terminal pile crown respectively, by threephase cable Terminal pile crown covers, and it is kept safe enough distance with ground potential around；Meanwhile by the extension of insulating boot by cable The current potential of terminal pile crown is led to inside insulating boot on the outside of position in storehouse；Then, pressure test high-voltage connection is directly connected in insulating boot The metallic conductor that portion is drawn, proceeds by pressure test.