Device and method for testing polarization-depolarization current of double-layer composite insulating medium of cable

Abstract

The invention relates to the technical field of high-voltage cable and accessory insulating materials, and particularly discloses a cable double-layer composite insulating medium polarization-depolarization current testing device and method.The testing device comprises a direct-current high-voltage power source, a testing electrode system, a pressure adjusting system, a temperature control system and a current information collecting system; the test electrode system is used for loading direct-current voltage to the sample; the pressure adjusting system is used for adjusting the pressure applied to the sample by the test electrode system; the temperature control system is used for adjusting the temperature of the test electrode system during testing; and the current information acquisition system is connected to a circuit between the test electrode system and the direct-current high-voltage power supply and is used for acquiring current information in the circuit. According to the invention, the pressure and temperature control of the test electrode system can be realized, and the problem that the complex structure and actual operation conditions of the composite insulating medium are not considered in the existing test device is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage cables and accessory insulation materials, and in particular to a polarization-depolarization current testing device and method for a cable double-layer composite insulation medium. Background Art

[0002] In recent years, the application of nondestructive testing methods such as the polarization-depolarization current method in evaluating insulation aging in power equipment has increased significantly. The polarization current of the test sample under an applied DC voltage and the depolarization current after the applied DC voltage is removed contain rich information about dielectric properties, such as dielectric polarization and the accumulation and transfer of space charge in the dielectric. This information can be used to analyze the dielectric's insulation defects.

[0003] Currently, conventional polarization-depolarization test devices are primarily designed for single insulating media. However, in engineering applications, power equipment insulation often consists of two or more layers of dielectric composites, such as the cross-linked polyethylene-silicone rubber and silicone rubber-epoxy insulation structures commonly found in cable accessories. Therefore, existing polarization-depolarization current test devices for insulating media fail to account for the complex structures and actual operating conditions of composite insulating media, resulting in certain limitations in their application. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for testing polarization-depolarization current of a double-layer composite insulation medium of a cable, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides a polarization-depolarization current test device for a double-layer composite insulation medium of a cable, comprising:

[0006] DC high voltage power supply;

[0007] A test electrode system, the test electrode system being electrically connected to the DC high-voltage power supply and used to apply a DC voltage to a sample, the sample being a double-layer composite insulating medium;

[0008] a pressure regulating system, the pressure regulating system being used to regulate the pressure applied by the test electrode system to the sample;

[0009] a temperature control system, wherein the test electrode system, the pressure regulating system and the sample are all arranged in the temperature control system, and the temperature control system is used to regulate the temperature of the test electrode system during testing;

[0010] A current information acquisition system is connected to the circuit between the test electrode system and the DC high-voltage power supply, and is used to acquire current information in the circuit.

[0011] Preferably, the test electrode system comprises:

[0012] a high-voltage electrode, the high-voltage electrode being mounted on the head of the pressure regulating system and connected to the positive electrode of the DC high-voltage power supply;

[0013] a measuring electrode, the measuring electrode being arranged opposite to the high-voltage electrode, and the sample being arranged between the measuring electrode and the high-voltage electrode;

[0014] A guard electrode, the guard electrode being mounted on the periphery of the measuring electrode and being arranged in parallel with the measuring electrode;

[0015] an insulating member, the insulating member being disposed between the measuring electrode and the guard electrode, the measuring electrode and the guard electrode being electrically isolated from each other by the insulating member;

[0016] An insulating base, on which the measuring electrode, the protective electrode and the insulating member are all fixedly mounted.

[0017] Preferably, a multi-touch switch is connected between the high-voltage electrode and the DC high-voltage power supply, a short-circuit line is connected to the positive pole of the DC high-voltage power supply, and the end of the short-circuit line is connected to the multi-touch switch; a ground wire is provided at the negative pole of the DC high-voltage power supply, and the ground wire is located between the short-circuit line and the DC high-voltage power supply.

[0018] Preferably, the pressure regulating system comprises:

[0019] a press base, the insulating base being arranged on the press base;

[0020] a press, said press being mounted on said press base;

[0021] a retractable metal rod, through which the high-voltage electrode is mounted on the head of the press;

[0022] A pressure regulating knob is mounted on the telescopic metal rod and is used to adjust the pressure between the high-voltage electrode and the measuring electrode.

[0023] Preferably, the current information acquisition system includes a high-precision ammeter and a computer, the high-precision ammeter is electrically connected to the computer, and the computer is used to control the operation of the high-precision ammeter and collect data; the high-precision ammeter is arranged on the outside of the temperature control system, and one end of the high-precision ammeter is grounded.

[0024] Preferably, the temperature control system includes an oven and a temperature controller, and the test electrode system, the pressure regulating system and the sample are all arranged in the oven;

[0025] The oven is provided with a plurality of electrical interfaces, which are respectively a first interface, a second interface, a third interface and a fourth interface; the first interface and the third interface are electrically connected to the high-voltage electrode, the fourth interface is electrically connected to the protective electrode, and the measuring electrode and the protective electrode are both electrically connected to the second interface;

[0026] The upper temperature control end of the temperature controller is electrically connected to the third interface for controlling the temperature of the high-voltage electrode; the lower temperature control end of the temperature controller is electrically connected to the fourth interface for controlling the temperature of the measuring electrode and the protective electrode;

[0027] The input end of the current information acquisition system is electrically connected to the second interface.

[0028] Preferably, the second interface is a triaxial flange terminal; the flange square plate of the triaxial flange terminal is fixed to the oven by bolts; the measuring electrode is connected to the inner conductor of the triaxial flange terminal; and the protective electrode is connected to the inner shield of the triaxial flange terminal.

[0029] Preferably, the guard electrode is a ring electrode, the measuring electrode is a cylindrical electrode, and the distance between the guard electrode and the measuring electrode is not less than 2 mm.

[0030] Preferably, the double-layer composite insulating medium is composed of a silicone rubber sheet sample and a cross-linked polyethylene sheet sample.

[0031] A method for testing polarization-depolarization current of a double-layer composite insulation medium of a cable is performed using the above-mentioned polarization-depolarization current testing device of the double-layer composite insulation medium of a cable, and specifically comprises the following steps:

[0032] Two different insulating materials are prepared into a double-layer composite insulating medium sample;

[0033] The prepared sample is wiped clean with anhydrous ethanol and placed on the measuring electrode. The required pressure is applied to the sample through the pressure regulating system, and the test electrode system is heated to the preset temperature through the temperature controller.

[0034] Control the closed position of the multi-touch switch to connect the DC high-voltage power supply to the high-voltage electrode to polarize the sample. At the same time, the high-precision ammeter controlled by the computer collects the polarization current.

[0035] After polarization is completed, turn off the DC high-voltage power supply, change the closed position of the multi-touch switch, short-circuit the sample, and collect the polarization current through a high-precision ammeter at the same time. Stop collecting the polarization current after a certain period of time, and keep the test environment quiet during the test.

[0036] Compared with the prior art, the present invention has the following advantages and technical effects:

[0037] The present invention realizes pressure and temperature control of the test electrode system by adding a pressure regulating system and a temperature control system, thereby solving the problem that the complex structure and actual operating conditions of the composite insulating medium are not considered in the existing test device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 This is a schematic structural diagram of a polarization-depolarization current test device for a double-layer composite insulation medium of a cable according to the present invention;

[0040] Figure 2 A top view of the test electrode system of the present invention;

[0041] Figure 3 Schematic diagram of polarization current test results of a cross-linked polyethylene / silicone rubber double-layer composite insulation medium sample according to an embodiment of the present invention;

[0042] Figure 4 Schematic diagram of depolarization current test results of a cross-linked polyethylene / silicone rubber double-layer composite insulating medium sample in an embodiment of the present invention;

[0043] In the figure: 1. Double-layer composite insulating medium; 2. DC high-voltage power supply; 3. Multi-touch switch; 4. High-voltage electrode; 5. Measuring electrode; 6. Guard electrode; 7. Insulator; 8. Insulating base; 9. Press base; 10. Press; 11. Retractable metal rod; 12. Pressure adjustment knob; 13. Oven; 14. First interface; 15. Second interface; 16. Third interface; 17. Fourth interface; 18. High-precision ammeter; 19. Temperature controller; 20. Computer. DETAILED DESCRIPTION

[0044] It should be noted that, unless there is a conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other. The embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0045] like Figures 1 to 2 As shown, the present invention provides a polarization-depolarization current test device for a cable double-layer composite insulation medium, comprising:

[0046] DC high voltage power supply 2;

[0047] A test electrode system, the test electrode system is electrically connected to a DC high-voltage power supply 2, and the test electrode system is used to apply a DC voltage to the sample, and the sample is a double-layer composite insulating medium 1;

[0048] Pressure regulation system: The pressure regulation system is used to adjust the pressure applied by the test electrode system on the sample so that the sample conforms to the actual state during operation;

[0049] Temperature control system: the test electrode system, pressure regulation system and specimen are all arranged in the temperature control system, and the temperature control system is used to adjust the temperature of the test electrode system during testing;

[0050] The current information acquisition system is connected to the circuit between the test electrode system and the DC high-voltage power supply 2. The current information acquisition system is used to collect current information in the circuit.

[0051] To further optimize the solution, the test electrode system includes:

[0052] The high-voltage electrode 4 is installed on the head of the pressure regulating system, and the high-voltage electrode 4 is connected to the positive electrode of the DC high-voltage power supply 2;

[0053] Measuring electrode 5, measuring electrode 5 is arranged opposite to high voltage electrode 4, and the sample is arranged between measuring electrode 5 and high voltage electrode 4;

[0054] The protective electrode 6 is installed on the periphery of the measuring electrode 5 and is arranged in parallel with the measuring electrode 5;

[0055] The insulating member 7 is provided between the measuring electrode 5 and the guard electrode 6. The measuring electrode 5 and the guard electrode 6 are electrically isolated from each other by the insulating member 7.

[0056] The insulating base 8 , the measuring electrode 5 , the protective electrode 6 and the insulating member 7 are all fixedly mounted on the insulating base 8 .

[0057] The electrode material may be stainless steel 1Cr13Ni9T, the insulating member 7 may be made of polytetrafluoroethylene, and the insulating base 8 may be made of epoxy resin.

[0058] To further optimize the solution, a multi-touch switch 3 is connected between the high-voltage electrode 4 and the DC high-voltage power supply 2, a short-circuit line is connected to the positive pole of the DC high-voltage power supply 2, and the end of the short-circuit line is connected to the multi-touch switch 3; a ground wire is provided at the negative pole of the DC high-voltage power supply 2, and the ground wire is located between the short-circuit line and the DC high-voltage power supply 2.

[0059] To further optimize the solution, the pressure regulation system includes:

[0060] A press base 9, an insulating base 8 is arranged on the press base 9;

[0061] A press 10, which is mounted on a press base 9;

[0062] A retractable metal rod 11, through which the high-voltage electrode 4 is mounted on the head of the press 10;

[0063] The pressure regulating knob 12 is mounted on the retractable metal rod 11 and is used to adjust the pressure between the high-voltage electrode 4 and the measuring electrode 5 .

[0064] The present invention uses a retractable metal rod 11 in the pressure regulating system to lower the high-voltage electrode 4 to the sample surface through a hydraulic device and apply pressure. The sample is loaded with a pressure of 0.1Mpa to 1Mpa through the pressure regulating knob 12 to simulate the interference fit between the silicone rubber insulation and the cross-linked polyethylene insulation of the intermediate joint of the high-voltage cable.

[0065] To further optimize the solution, the current information acquisition system includes a high-precision ammeter 18 and a computer 20. The high-precision ammeter 18 is electrically connected to the computer 20. The computer 20 is used to control the operation of the high-precision ammeter 18 and collect data. The high-precision ammeter 18 is arranged on the outside of the temperature control system, and one end of the high-precision ammeter 18 is grounded.

[0066] According to a further optimized solution, the temperature control system includes an oven 13 and a temperature controller 19, and the test electrode system, the pressure regulating system and the sample are all arranged in the oven 13; the oven 13 is used to shield electromagnetic interference in the environment.

[0067] The oven 13 is provided with multiple electrical interfaces, namely a first interface 14, a second interface 15, a third interface 16 and a fourth interface 17; the first interface 14 and the third interface 16 are electrically connected to the high-voltage electrode 4, the fourth interface 17 is electrically connected to the guard electrode 6, and the measuring electrode 5 and the guard electrode 6 are both electrically connected to the second interface 15;

[0068] The upper temperature control end of the temperature controller 19 is electrically connected to the third interface 16 for controlling the temperature of the high-voltage electrode 4; the lower temperature control end of the temperature controller 19 is electrically connected to the fourth interface 17 for controlling the temperature of the measuring electrode 5 and the protective electrode 6;

[0069] The input end of the current information acquisition system is electrically connected to the second interface 15 .

[0070] Further optimized, the second interface 15 is a triaxial flange terminal; the flange square plate of the triaxial flange terminal is fixed to the oven 13 by bolts; the measuring electrode 5 is connected to the inner conductor of the triaxial flange terminal; and the guard electrode 6 is connected to the inner shield of the triaxial flange terminal.

[0071] According to a further optimized solution, the high-voltage electrode 4 is a cylindrical electrode with a diameter of 74 mm, the measuring electrode 5 is a cylindrical electrode with a diameter of 50 mm, the insulating member 7 has a width of 2 mm, and the protective electrode 6 is a ring electrode with a width of 10 mm.

[0072] To further optimize the solution, the double-layer composite insulating medium 1 consists of a silicone rubber sheet sample and a cross-linked polyethylene sheet sample. The two sheet samples are pressed under a certain pressure to form a cross-linked polyethylene / silicone rubber double-layer dielectric composite sample. Finally, it is short-circuited in a vacuum drying oven for 24 hours to eliminate residual surface charge. The temperature in the vacuum drying oven is set to 60°C.

[0073] A method for testing polarization-depolarization current of a double-layer composite insulation medium of a cable, comprising the following steps:

[0074] S1. Prepare a double-layer composite insulating medium 1 sample from two different insulating materials;

[0075] S2. Wipe the prepared sample clean with anhydrous ethanol and place it on the measuring electrode 5. Align the center of the sample with the center of the measuring electrode 5. Adjust the pressure control knob to the preset pressure value so that the high-voltage electrode 4 slowly descends on the sample and applies the corresponding pressure. At the same time, the test electrode system is heated to a preset temperature through the temperature controller 19.

[0076] S3, controlling the closed position of the multi-touch switch 3 to connect the DC high-voltage power supply 2 to the high-voltage electrode 4 to polarize the sample, while simultaneously controlling the high-precision ammeter 18 through the computer 20 to collect the polarization current;

[0077] S4. After polarization is completed, turn off the DC high-voltage power supply 2, change the closed position of the multi-touch switch 3, short-circuit the sample, and collect the polarization current through the high-precision ammeter 18 at the same time. Stop collecting the polarization current after a certain period of time. Keep the test environment quiet during the test to reduce the impact of noise on the measurement results.

[0078] Example

[0079] First, prepare a cross-linked polyethylene / silicone rubber double-layer composite insulating dielectric specimen. The specimen measures 100mm*100mm*1mm. The silicone rubber is A / B two-component addition-type liquid silicone rubber. Using a flat-plate vulcanizer, hot-press vulcanize the specimens at 170°C and 15MPa to form sheet specimens. Each sheet specimen is preheated at 80°C for 10 minutes and then pressed under pressure to form a cross-linked polyethylene / silicone rubber double-layer dielectric composite specimen. Finally, short-circuit the specimen in a vacuum drying oven for 24 hours to eliminate residual surface charge. The temperature in the vacuum drying oven is set at 60°C.

[0080] Place the sample in the test electrode system, adjust the pressure knob to 0.2 MPa, and adjust the temperature controller 19 to raise the temperature of the test electrode system to 90°C.

[0081] Polarize the sample, place the multi-touch switch 3 in position 1, turn on the DC high-voltage power supply 2 to output a 1 kV DC voltage, and polarize the sample. At the same time, start the high-precision ammeter 18 through the control system of the computer 20 to collect the polarization current. The collection time is 1800 s and the collection interval is 1 s.

[0082] The sample is short-circuited, the multi-touch switch 3 is placed in position 2, the DC high-voltage power supply 2 is turned off, the sample is short-circuited, and the high-precision ammeter 18 continues to collect depolarization current with a collection time of 1800s and a collection interval of 1s.

[0083] The polarization current and depolarization current collected in this embodiment are as follows Figure 3 and Figure 4 shown.

[0084] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A cable double-layer composite insulation medium polarization-depolarization current test device, characterized in that: include: DC high voltage power supply (2); A test electrode system, the test electrode system being electrically connected to the DC high-voltage power supply (2), the test electrode system being used to apply a DC voltage to a sample, the sample being a double-layer composite insulating medium (1); a pressure regulating system, the pressure regulating system being used to regulate the pressure applied by the test electrode system to the sample; a temperature control system, wherein the test electrode system, the pressure regulating system and the sample are all arranged in the temperature control system, and the temperature control system is used to regulate the temperature of the test electrode system during testing; A current information acquisition system is provided, wherein the current information acquisition system is connected to the circuit between the test electrode system and the DC high-voltage power supply (2), and is used for acquiring current information in the circuit.

2. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 1, characterized in that: The test electrode system comprises: a high-voltage electrode (4), the high-voltage electrode (4) being mounted on the head of the pressure regulating system, and the high-voltage electrode (4) being connected to the positive electrode of the DC high-voltage power supply (2); a measuring electrode (5), the measuring electrode (5) being arranged opposite to the high-voltage electrode (4), and the sample being arranged between the measuring electrode (5) and the high-voltage electrode (4); A protective electrode (6), the protective electrode (6) being installed on the periphery of the measuring electrode (5), the protective electrode (6) being arranged in parallel with the measuring electrode (5); an insulating member (7), the insulating member (7) being arranged between the measuring electrode (5) and the protective electrode (6), the measuring electrode (5) and the protective electrode (6) being electrically isolated by the insulating member (7); An insulating base (8), on which the measuring electrode (5), the protective electrode (6) and the insulating member (7) are all fixedly mounted.

3. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 2, characterized in that: A multi-touch switch (3) is connected between the high-voltage electrode (4) and the DC high-voltage power supply (2); a short-circuit line is connected to the positive pole of the DC high-voltage power supply (2), and the end of the short-circuit line is connected to the multi-touch switch (3); a ground line is provided at the negative pole of the DC high-voltage power supply (2), and the ground line is located between the short-circuit line and the DC high-voltage power supply (2).

4. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 2, characterized in that: The pressure regulating system comprises: A press base (9), wherein the insulating base (8) is arranged on the press base (9); A press (10), the press (10) being mounted on the press base (9); a retractable metal rod (11), wherein the high-voltage electrode (4) is mounted on the head of the press (10) via the retractable metal rod (11); A pressure regulating knob (12) is mounted on the telescopic metal rod (11), and the pressure regulating knob (12) is used to regulate the pressure between the high-voltage electrode (4) and the measuring electrode (5).

5. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 3, characterized in that: The current information acquisition system comprises a high-precision ammeter (18) and a computer (20), wherein the high-precision ammeter (18) is electrically connected to the computer (20), and the computer (20) is used to control the operation of the high-precision ammeter (18) and collect data; the high-precision ammeter (18) is arranged outside the temperature control system, and one end of the high-precision ammeter (18) is grounded.

6. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 2, characterized in that: The temperature control system includes an oven (13) and a temperature controller (19), and the test electrode system, the pressure regulating system and the sample are all arranged in the oven (13); The oven (13) is provided with a plurality of electrical interfaces, which are respectively a first interface (14), a second interface (15), a third interface (16) and a fourth interface (17); the first interface (14) and the third interface (16) are electrically connected to the high-voltage electrode (4), the fourth interface (17) is electrically connected to the protective electrode (6), and the measuring electrode (5) and the protective electrode (6) are both electrically connected to the second interface (15); The upper temperature control end of the temperature controller (19) is electrically connected to the third interface (16) for controlling the temperature of the high-voltage electrode (4); the lower temperature control end of the temperature controller (19) is electrically connected to the fourth interface (17) for controlling the temperature of the measuring electrode (5) and the protective electrode (6); The input end of the current information acquisition system is electrically connected to the second interface (15).

7. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 6, characterized in that: The second interface (15) is a triaxial flange terminal; the flange square plate of the triaxial flange terminal is fixed to the oven (13) by bolts; the measuring electrode (5) is connected to the inner conductor of the triaxial flange terminal; and the protective electrode (6) is connected to the inner shield of the triaxial flange terminal.

8. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 2, characterized in that: The protective electrode (6) is a ring electrode, the measuring electrode (5) is a cylindrical electrode, and the distance between the protective electrode (6) and the measuring electrode (5) is not less than 2 mm.

9. The cable double-layer composite insulation medium polarization-depolarization current test device according to claim 6, characterized in that: The double-layer composite insulating medium (1) consists of a silicone rubber sheet sample and a cross-linked polyethylene sheet sample.

10. A method for testing polarization-depolarization current of a double-layer composite insulation medium of a cable, characterized in that: The polarization-depolarization current test device for the double-layer composite insulation medium of a cable according to any one of claims 1 to 9 specifically comprises the following steps: A double-layer composite insulating medium (1) sample is prepared from two different insulating materials; The prepared sample is wiped clean with anhydrous ethanol and placed on the measuring electrode (5), and the required pressure is applied to the sample through the pressure regulating system, while the test electrode system is heated to a preset temperature through the temperature controller (19); Controlling the closed position of the multi-touch switch (3) to connect the DC high-voltage power supply (2) to the high-voltage electrode (4) to polarize the sample, while simultaneously controlling the high-precision ammeter (18) through the computer (20) to collect the polarization current; After polarization is completed, the DC high voltage power supply (2) is turned off, the closed position of the multi-touch switch (3) is changed, the sample is short-circuited, and the polarization current is collected by the high-precision ammeter (18). The collection of polarization current is stopped after a certain period of time, and the test environment is kept quiet during the test.

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