Breakdown experiment electrode structure for simulating local overheating working condition of cable insulation layer

Abstract

The utility model relates to a breakdown experiment electrode structure simulating a local overheating working condition of a cable insulation layer, a cable insulation layer to be tested is placed between a high-voltage side spherical electrode and a low-voltage side spherical electrode, and the high-voltage side spherical electrode and the low-voltage side spherical electrode are respectively provided with a liquid phase inlet and a liquid phase outlet. Liquid-phase circulating pipelines are arranged in the high-voltage side spherical electrode and the low-voltage side spherical electrode, the liquid-phase circulating pipelines are communicated with a liquid-phase inlet and a liquid-phase outlet, the liquid-phase inlet is connected with a liquid inlet pipe, the liquid inlet pipe is connected to a medium storage tank through a circulating pump, the liquid-phase outlet is connected with a liquid outlet pipe, and the liquid outlet pipe is connected to the medium storage tank. A traditional ball-ball electrode structure is improved, the optimal curvature radius of the electrode is obtained through optimization calculation, meanwhile, a circulating liquid phase heating pipeline is integrated on the electrode, the local temperature of the metal electrode is controllable, and then the special working condition of local overheating of an insulating layer is simulated.

Description

TECHNICAL FIELD

[0001] The utility model belongs to cable insulation technical field, especially related to a breakdown experiment electrode structure of simulation cable insulation layer local overheating working condition. BACKGROUND

[0002] With voltage grade, installed capacity improves year by year, in modern electric power transmission and electrical equipment operation system, cable as the key link of electric energy transmission, its safety, stability receives extensive attention.As directly related to the safe and stable operation of power system and electric energy transmission efficiency core problem, cable insulation layer's technical level and quality are especially important.Especially with the increase of transmission capacity, the cable insulation layer local heating problem caused by extrusion or material defect gradually causes attention.How to carry out the breakdown experiment of cable insulation layer local overheating this special working condition becomes the important content of cable insulation field.

[0003] Traditional breakdown experiment for cable insulation layer is often carried out at room temperature, and it is difficult to simulate the cable center heating caused by joule heat in actual operation process.The breakdown experiment carried out for temperature problem often adopts oil bath heating method, and the cable insulation layer and electrode structure are immersed in insulating oil, and the breakdown experiment under different temperatures is completed by controlling oil temperature.However, this method is limited to simulate uniform temperature environment, and the traditional method is difficult to realize for the local overheating caused by the non-uniformity of cable insulation layer or the local defect of material.A large number of field investigations and laboratory studies found that the local high temperature under special working conditions is the key to cause cable insulation failure.Therefore, in order to clarify the influence of local overheating problem on cable insulation layer breakdown voltage and improve the safety performance of cable insulation, it is necessary to design a breakdown experiment electrode structure for simulating cable insulation layer local overheating working condition. UTILITY MODEL CONTENTS

[0004] The utility model discloses a kind of breakdown experiment electrode structures for simulating cable insulation layer local overheating working condition, improve traditional "ball-ball" electrode structure, obtain its optimal curvature radius by optimization calculation, while, circulating liquid phase heating pipeline is integrated on electrode, realize that metal electrode local temperature is controllable, then simulate this special working condition of insulation layer local overheating.

[0005] The utility model solves its technical problem by the following technical scheme:

[0006] The utility model provides an electrode structure of breakdown experiment of simulating the local overheating condition of cable insulation layer, including high voltage side spherical electrode and low voltage side spherical electrode, place the cable insulation layer of measurement between high voltage side spherical electrode and low voltage side spherical electrode, all be provided with liquid phase entrance and liquid phase export on high voltage side spherical electrode and low voltage side spherical electrode, all be provided with liquid phase circulation pipeline in high voltage side spherical electrode and low voltage side spherical electrode, liquid phase circulation pipeline with liquid phase entrance and liquid phase export intercommunication, liquid phase entrance is connected with liquid inlet pipe, liquid inlet pipe is connected to medium storage tank through circulating pump, liquid phase export is connected with liquid outlet pipe, and liquid outlet pipe is connected to medium storage tank.

[0007] Moreover, the diameter of the liquid phase circulation pipeline is 3-5 mm.

[0008] Moreover, the high voltage side spherical electrode and the low voltage side spherical electrode each include a segmented spherical head electrode and a cylindrical electrode, the tail of the spherical head electrode is threadedly connected to the cylindrical electrode, the radius of curvature of the spherical head electrode is 8-12.5 mm, and the length of the cylindrical electrode is 40-80 mm.

[0009] Moreover, the medium in the medium storage tank is high-temperature insulation oil, and the controllable heating temperature of the medium storage tank is 25-120 DEG C.

[0010] The utility model discloses the advantages and beneficial effects are:

[0011] 1. The radius of curvature of the spherical head of the high voltage side spherical electrode and the low voltage side spherical electrode is obtained through optimized calculation, which facilitates reasonable selection of the electrode structure.

[0012] 2. The utility model integrates the liquid phase circulation pipeline to the spherical electrode, realizes the simulation of the local high-temperature condition, and is more convenient for the breakdown experiment of the cable insulation layer.

[0013] 3. The utility model has a controllable high temperature, which realizes the simulation of different local high temperatures caused by various defects. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is the plan view of the high voltage side spherical electrode or the low voltage side spherical electrode of the utility model;

[0015] Figure 2 It is the three-dimensional structure schematic view of the high voltage side spherical electrode or the low voltage side spherical electrode of the utility model;

[0016] Figure 3 It is the structure schematic view of the breakdown experiment electrode structure of the utility model for heating;

[0017] Figure 4 It is the circuit schematic view of the breakdown experiment of the utility model.

[0018] Reference Signs List

[0019] 1-liquid inlet, 2-liquid outlet, 3-liquid inlet pipe, 4-liquid outlet pipe, 5-ball head electrode, 6-cylindrical electrode, 7-oil bath, 8-heating table, 9-medium storage tank, 10-circulating pump, 11-liquid circulating pipeline, 12-high voltage side ball electrode, 13-insulation layer of cable to be tested, 14-low voltage side ball electrode. DETAILED DESCRIPTION

[0020] The utility model will make further detailed description below through specific embodiment, the following embodiment is only descriptive, is not limitative, can not be defined the protection scope of the utility model with this.

[0021] As Figure 1 , 2 The utility model discloses a breakdown experiment electrode structure of simulating local overheating working condition of cable insulation layer, and its innovative points are as follows: including high voltage side ball electrode 12 and low voltage side ball electrode 14, the high voltage side ball electrode and low voltage side ball electrode between place insulation layer 13 of cable to be tested, the high voltage side ball electrode and low voltage side ball electrode all are provided with liquid inlet 1 and liquid outlet 2, the high voltage side ball electrode and low voltage side ball electrode all are provided with liquid circulating pipeline 11, the liquid circulating pipeline is connected with liquid inlet and liquid outlet, the liquid inlet is connected with liquid inlet pipe 3, the liquid inlet pipe is connected to medium storage tank 9 through circulating pump 10, the liquid outlet is connected with liquid outlet pipe 4, and the liquid outlet pipe is connected to the medium storage tank.

[0022] The diameter of the liquid circulating pipeline is 3-5mm.

[0023] The high voltage side ball electrode and low voltage side ball electrode all include segmented ball head electrode 5 and cylindrical electrode 6, the tail of the ball head electrode is screwed with the cylindrical electrode, the curvature radius of the ball head electrode is 8-12.5mm, and the length of the cylindrical electrode is 40-80mm.

[0024] The medium in the medium storage tank is high-temperature insulation oil, and the controllable heating temperature of the medium storage tank is 25-120 DEG C.

[0025] The utility model improves the traditional "ball-ball" electrode structure, obtains the optimal curvature radius through optimization calculation, integrates the circulating liquid heating pipeline on the electrode at the same time, realizes that the local temperature of metal electrode is controllable, and then simulates this special working condition of insulation layer local overheating.

[0026] Figure 3As shown, when breakdown experiment is carried out, the electrode structure is heated, 10L of insulating oil is stored in the controllable temperature circulating oil tank, and the oil tank can be heated through the heating device of the oil tank, and the temperature error is ±0.5℃. The outlet end of the oil tank is connected with a circulating pump, and the circulating pump can input the high-temperature insulating oil in the oil tank into Figure 1 and Figure 2 As shown, the liquid inlet pipe of the high-voltage side spherical electrode or the low-voltage side spherical electrode is connected with the outlet pipe of the high-voltage side spherical electrode or the low-voltage side spherical electrode and the inlet end of the controllable temperature circulating oil tank, and the complete circulation of the insulating oil is formed. Figure 3 The oil bath pot 7 is used for overall heating of the cable insulation layer to be tested, the high-voltage side spherical electrode and the low-voltage side spherical electrode, and the cable insulation layer to be tested, the high-voltage side spherical electrode and the low-voltage side spherical electrode are immersed in the oil bath pot 7, which is used to simulate the thermal effect of the cable conductor and the insulation layer as a whole under normal working conditions. The insulating oil in the oil bath pot is heated by an external heating table 8, and the heating table can increase the temperature of the oil bath pot from room temperature to 85℃.

[0027] In order to avoid the occurrence of surface flashover or air breakdown at the edge of the sample, the sample to be tested and the spherical electrode are completely immersed in the transformer oil during the experiment. During the experiment, the voltage is applied, and the voltage rising rate is controlled to be 0.5kV / s until the sample is broken down. Each sample is tested for 15 times to ensure the reliability of the results. The experimental circuit diagram is shown in Figure 4 As shown, by using the spherical electrode to clamp the cable insulation layer to be tested, a quasi-uniform electric field can be formed on the cable insulation layer to be tested. The sample is cut into a square, and during the test, the electrode and the cable insulation layer to be tested are immersed in the transformer oil to prevent the occurrence of surface flashover or air breakdown at the edge of the sample. The voltage regulator is the source of the applied voltage, that is, the power supply, and the adjustment range of the applied alternating voltage is 0 to 200kV. The protection resistor is used to ensure that the overall circuit will not be short-circuited when the insulation layer sample is broken down, and the size is 1MΩ. The oscilloscope is used to observe the voltage waveform applied to the insulation layer.

[0028] The overall operation process of the experiment is as follows:

[0029] (1) The spherical electrode of the utility model is installed into the oil bath pot, the curvature radius of the electrode is determined according to the size of the cable insulation layer to be tested, for example, if the sample is a square sample of 3*3mm, the curvature radius is selected to be 12.50mm;

[0030] (2) The cable insulation layer to be tested is clamped between the two spherical electrodes, and it is ensured that the sample will not be deviated in the experiment;

[0031] (3) The liquid phase circulating pipeline of the spherical electrode is connected with the circulating pump and the controllable temperature oil tank;

[0032] (4) Fill the insulating oil in the oil bath pot and the oil tank, and make sure that the insulating oil in the oil tank completely covers the spherical electrode and the cable insulation layer to be tested;

[0033] (5) Turn on the heating function of the oil tank and the heating table, and set the temperature according to the experiment, for example, set the oil tank heating temperature to 100 DEG C, and the heating table temperature to 60 DEG C;

[0034] (6) Turn on the circulating pump, input the insulating oil in the oil tank heated to 100 DEG C to the inside of the spherical electrode through the pipeline, heat the spherical electrode, and wait for at least 10 minutes in the heating circulation process, so as to make sure that the spherical electrode has realized local overheating and the oil bath environment in the oil bath pot is stable (that is, one side metal electrode is heated to 100 DEG C, the oil bath temperature is 60 DEG C, at this time, the temperature of the other side spherical electrode and the cable insulation layer to be tested is 60 DEG C, and then the simulation of local overheating is realized).

[0035] (7) According to the circuit connection, the rising rate of the applied voltage is 0.5 kV / s. The sample of each component is tested for at least 15 times, and finally the breakdown voltage result of the cable insulation layer under the local overheating condition is obtained. Figure 4

[0036] Although the embodiments and drawings of the utility model are disclosed for the purpose of illustration, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the utility model and the appended claims, therefore, the scope of the utility model is not limited to the content disclosed in the embodiments and drawings.​

Claims

1. A breakdown test electrode structure for simulating local overheating conditions in cable insulation, characterized in that: The device includes a high-voltage side spherical electrode and a low-voltage side spherical electrode, with the insulation layer of the cable under test placed between the high-voltage side spherical electrode and the low-voltage side spherical electrode. Each of the high-voltage side spherical electrode and the low-voltage side spherical electrode is provided with a liquid phase inlet and a liquid phase outlet. Each of the high-voltage side spherical electrode and the low-voltage side spherical electrode is provided with a liquid phase circulation pipe, which is connected to the liquid phase inlet and the liquid phase outlet. The liquid phase inlet is connected to a liquid inlet pipe, which is connected to a medium storage tank through a circulation pump. The liquid phase outlet is connected to a liquid outlet pipe, which is connected to the medium storage tank.

2. The breakdown test electrode structure for simulating local overheating of cable insulation layer according to claim 1, characterized in that: The diameter of the liquid phase circulation pipe is 3-5 mm.

3. The breakdown test electrode structure for simulating local overheating of cable insulation layer according to claim 1, characterized in that: Both the high-voltage side spherical electrode and the low-voltage side spherical electrode include a segmented ball-head electrode and a cylindrical electrode. The tail of the ball-head electrode is threadedly connected to the cylindrical electrode. The radius of curvature of the ball-head electrode is 8 to 12.5 mm, and the length of the cylindrical electrode is 40 to 80 mm.

4. The breakdown test electrode structure for simulating local overheating of cable insulation layer according to claim 1, characterized in that: The medium in the medium storage tank is high-temperature insulating oil, and the controllable heating temperature of the medium storage tank is 25-120℃.

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