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E-mail
3440125819@qq.com
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Phone
18911397564
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Address
No.1 Shangdi 10th Street, Shangdi Science and Technology Park, Haidian District, Beijing
Beijing Beiguang Jingyi Instrument Equipment Co., Ltd
3440125819@qq.com
18911397564
No.1 Shangdi 10th Street, Shangdi Science and Technology Park, Haidian District, Beijing
This voltage breakdown tester is an upgraded product for our company
Features include wireless Bluetooth control system, remote control, multi person operation, network sharing, human-machine separation, remote operation, automatic cruise detection, etc
Company: Beijing Beiguang Jingyi Instrument Equipment Co., Ltd
：www.beiguangjy。。 ｃｎ
： 53305280 53305279
Beiguang Precision Instrument provides you with: *, stable and convenient testing instruments
Detailed description of breakdown voltage tester/dielectric breakdown strength tester:
Breakdown voltage tester/dielectric breakdown strength tester/Voltage breakdown strength tester/Insulation material electrical strength testing machine/dielectric breakdown voltage meter
Voltage breakdown testerMeet the standards:
GB1408-2006 GB/T1695-2005 GB/T3333 HG/T3330 /GB12656 /ASTM D149 .
Voltage breakdown testerOverview
BDJC-50KV adopts computer control and completes the power frequency voltage breakdown and power frequency withstand voltage test of insulation dielectric materials through human-machine dialogue. Suitable for testing the breakdown voltage, breakdown strength, and withstand voltage of solid insulation materials (such as insulation paints, resins and adhesives, impregnated fiber products, laminated products, mica and its products, plastics, film composite products, ceramics, and glass, etc.) under power frequency voltage. The instrument quickly and accurately collects, processes, accesses, displays, and prints various data during the experimental process.
technical indicators：
01. Input voltage: AC 220V
02. Output voltage: AC 0-50 KV;
DC 0-50 KV
03. Electrical capacity: 10KVA
04. High voltage classification: 0-10KV, 0-50KV
05. Boosting rate: 0.1-5.0kv
(Note: Meets standard requirements and can set different boost rates according to user needs)
06. Test method:
DC test: 1. Constant voltage boost 2. Gradient boost 3. Voltage withstand test
Communication test: 1. Constant voltage boost 2. Gradient voltage boost 3. Voltage withstand test
07. Test medium: air, test oil
08. Install a highly sensitive overcurrent protection device to ensure that the power is cut off within 0.05 seconds when the sample breaks down.
09. The instrument is equipped with a fault alarm system to prevent users from operating the faulty instrument and causing danger. (Upper computer alarm and lower computer alarm)
10. Support short circuit test requirements in a short period of time.
11. Voltage test accuracy: ≤ 1%.
12. The test voltage can be continuously adjusted from 0 to 100 KV.
13. The current can be collected to m * and real-time acquisition can be achieved.
14. Provide a calibration certificate for measurement units or a certificate for customer measurement units
15. Power supply: 220V ± 10% single-phase AC voltage and 50Hz ± 1% frequency
16. Current and voltage stability: External voltage fluctuation of 10% (optional with our company's voltage protector rated fluctuation voltage of 30%)
17. Boosting device: using non-contact components to uniformly boost voltage, eliminating the previous mechanical voltage regulation
18. Voltage endurance time: 0-6H to maintain relative voltage (software setting)
19. Breakdown sample: The size of the breakdown point of the sample can be adjusted, generally around 1-5mm
20. Oil bath with easy disassembly and assembly (can be customized according to customer needs, or oil bath can be omitted)
21. Chassis material: SUS304 stainless steel
22. Support human-machine separation for remote operations.
23. Control mode: optional PC/EPC
24. Communication method: Adopting the most advanced national technology wireless Bluetooth control, supporting 232/USB/Asia Pacific regional network ports.
Safety Instructions：
The experiment is conducted at a higher voltage, so we have taken necessary protective measures in the design to prevent accidents from occurring.
1. The experiment is conducted in a test chamber, and the sample can be placed in air or transformer oil. The safe discharge distance of the 50KV voltage head is less than 200mm for all sides, and there will be no danger even if it touches the box wall during the test.
2. The high voltage side tail end of the step-up transformer and the instrument casing are connected together, that is, the instrument casing is equipotential with the ground at that location.
3. Circuit protection: The instrument is equipped with overcurrent protection, overvoltage protection, undervoltage protection, short circuit protection, leakage protection circuits, etc.
complete machine composition：
1. Boosting component: consisting of a regulator and a high-voltage transformer, it is a 0-50KV boosting part.
2. Moving parts: The voltage regulator is uniformly adjusted by a stepper motor to change the voltage applied to the high-voltage transformer.
3. Testing component: a measurement circuit composed of integrated circuits. Transmit the detected analog signal and switch signal to the computer through the signal line.
4. Computer software: transmits the measurement and control signals collected by the detection equipment to the computer through intelligent circuits. The computer controls the operation of the equipment and processes the test results based on the collected information.
5. Test electrode: According to the national standard (1408.1-2006), three electrodes are provided with the equipment, with specific specifications of two electrodes of Ø 25mm × 25mm; One with a diameter of 75mm x 25mm.
operating steps：
1. Preparation before the experiment:
1) Turn on the main power switch on the right side of the testing machine and preheat for 15 minutes.
2) Open the computer and enter the Windows system. Double click the shortcut icon of this instrument software to open the test login interface, enter the login password to enter the test interface.
2. Switching between AC and DC tests
1) The high voltage output of this instrument is AC voltage. The method of obtaining direct current is to string a high-voltage silicon stack into the original circuit, making the test circuit a pulsating direct current voltage. The implementation process is that the silicon stack is already in the high-voltage insulation tower of the high-voltage transformer, and a short-circuit rod is usually used to short-circuit the high-voltage silicon stack. When a DC test is required, remove the short-circuit rod and connect the high-voltage silicon stack to the test circuit. At this time, the voltage in the circuit is a pulsating DC voltage.
2) Front panel DC/AC selection button. The status of this button cannot change the voltage properties of the device output. Pressing this button will simply connect the DC alarm circuit to the device. Instruct the user that when opening the box door, you need to discharge the high-voltage equalizing ball. Rotate the discharge pole so that the copper ball at the end of the discharge pole contacts the high-voltage equalizing ball. It is recommended that users keep the copper ball in contact with the high-voltage equalizing ball for more than five seconds each time they discharge.
3) The switching of AC/DC voltage in the experiment mainly depends on whether the short-circuit rod in the high-voltage insulation tower is removed. When the short-circuit rod is removed, the voltage on the high-voltage equalizing ball is DC voltage, and when the short-circuit rod is inserted, the voltage on the high-voltage equalizing ball is AC voltage. Refer to the schematic diagram on the left for the removal and insertion of the short-circuit rod.
4) In DC testing, the computer should also choose the DC state, otherwise the measured results will be incorrect. Simply put, there is a multiple relationship between AC voltage and DC voltage.
safety protection：
This machine has complete safety protection measures:
Circuit protection control of this experimental instrument: voltage automatically returns to zero after tripping
1. Overpressure protection
2. Test overcurrent protection
3. Test short-circuit protection
4. Safety test door protection
5. Software misoperation protection
6. Zero voltage reset protection
7. Test leakage protection
8. Independent grounding protection
9. End of experiment discharge protection
10. Equipment malfunction alarm protection
1. Sample processing
Dip a silk cloth in a solvent that has no corrosive effect on the sample and wipe it clean.
⑵ Preprocessing and Conditional Processing: The processing conditions and methods can be selected from Appendix Table 1 and Table 2 of this standard based on the performance requirements of the product. Special requirements may be specified separately by product standards.
The electrical strength of insulation materials varies with temperature and moisture content. Unless otherwise specified for the test material, the sample should be treated for at least 24 hours under conditions of 23 ± 2 ℃ and relative humidity (50 ± 5)%.
The sample that has been dampened or immersed in liquid media should be gently removed with filter paper before the test. The time from taking out the sample to the end of the test should not exceed 5 minutes.
2. Medium:
⑴ Gas medium: Air is used. If there is flashover, a soft silicone rubber anti arc ring can be added around the electrode. There is a circular gap of about one millimeter between the anti flying arc ring and the electrode, with a ring width of 30mm.
⑵ Liquid medium: Clean transformer oil is used for normal tests and hot tests below 90 ℃, and clean superheated cylinder oil is used for hot tests between 90 ℃ and 300 ℃.
3. Experimental environment:
⑴ Normal test environment:
The temperature is 20 ± 5 ℃ and the relative humidity is 65 ± 5%.
The conditions for hot state testing or humid environment testing shall be specified in Table 2 of the product standard reference record.
Preprocessing and conditioning of experiments:
Preprocessing: To reduce the impact of different placement conditions of the sample in the past, in order to ensure good repeatability and comparability of the test results. The preprocessing conditions can be selected from Table 1.
Table 1 Preprocessing Conditions
Temperature (°C) |
Relative humidity (%) |
Time (h) |
20±5 |
65±5 |
≥24 |
70±2 |
＜40 |
4 |
105±2 |
＜40 |
1 |
Condition treatment: Prior to the experiment, the sample is placed at a specified temperature in an atmosphere with a certain relative humidity or immersed in water (or other liquids) for a specified period of time to assess the degree to which material properties are affected by various factors such as temperature and humidity. The processing conditions are selected from Table 2. The conditions and methods for mechanical stress treatment shall be in accordance with the product standards.
Table 2 Condition Handling and Experimental Environment
project |
Temperature (°C) |
Time (h) |
Relative humidity (%) |
Precautions |
High temperature treatment and hot state testing environment |
90±2 105±2 120±2 130 ± 2 155±2 180±2 200±2 220±2 250±2 275±5 320±5 |
＜40h It can be determined by the relationship curve between the temperature, time, and performance of the sample |
The hot sample must reach the specified temperature of the sample |
|
Soak in distilled water, boiling water, or other liquids for treatment |
20±5 100±5 |
0.5, 1, 2, 4, 6, 8, 16, 24, 48, 96 |
|
|
Moisture treatment and humid environment |
20±5 |
95±3 |
0.5, 1, 2, 3, 4, 8, 16, 24, 48, 96, 7 days or integer multiples of 7 days |
1. Place the sample under the specified processing conditions and start timing. |
1. During the experiment, unrelated personnel should not be allowed to approach, as this testing instrument can generate high voltage and untrained personnel cannot use the equipment. There should be a supervisor during the experiment, and it should not be used alone. Just in case of unexpected situations.
2. If the equipment is not used for a long time, when using it again, first let the instrument be unloaded and pressurized once, that is, remove the wiring of the high-voltage electrode from the pressure equalizing ball. Check the computer test interface to see if the high voltage is normal.
3. In case of unexpected situations during the experiment, the power should be cut off in a timely manner, and the problem should be resolved before continuing the experiment.
4. The equipment should be placed steadily and on a sturdy ground. It is a cement floor to avoid resonance.
5. The casing of the device should be grounded with a protective earth wire during use, to ensure the safety of operators and equipment operation.
6. After using the equipment, turn off the power supply of all parts of the system and do not plug or unplug power cords with power on.
7. Connect the equipment according to the prescribed power supply voltage. Ensure that the circuit wiring is correct. Otherwise, it will damage the equipment.
8. The instrument should be placed indoors, and the laboratory should be clean, dry, and free of corrosive media. Non related personnel should not operate it casually.
9. Do not let the device cable touch the sharp edge to avoid scratching the cable insulation; Do not let the cable be pressed under heavy objects to avoid breaking the cable and causing a fire; Do not use cables to pull objects or tie objects with cables to avoid breaking the cables and causing the equipment to malfunction.
10. Do not let the equipment come into contact with water splashes, corrosive gases, flammable gases, and combustible materials. If not avoided, there may be a fire.
11. When moving equipment, cut off the power supply by unplugging the plug from the socket. It is prohibited to lay down the equipment or tilt it at an angle of more than 45 degrees when moving it.
12. Do not plug or unplug the power plug of the device while it is running.
1. The experiment is conducted in the test box, and when the door of the test box is opened, the power supply cannot be applied to the input terminal of the high-voltage transformer, that is, there is no voltage on the high-voltage side. The maximum safe distance between the high voltage electrode of the 20KV testing equipment and the test box wall is the closest distance, and there is no danger even if people touch the box wall during the test.
2. The equipment needs to be equipped with a separate protective grounding wire. Grounding protection is mainly used to reduce the strong electromagnetic interference caused by the breakdown of the sample to the surrounding area. It can also prevent the computer from losing control.
3. The circuit of the experimental equipment is equipped with multiple protection measures, mainly including overcurrent protection, voltage loss protection, leakage protection, short circuit protection, etc.
Notes:
During the testing process of this instrument, if the relative humidity of the air is greater than 70%, the distance between the two electrodes for air discharge will increase significantly. Therefore, please maintain a distance of 1.2 meters from the instrument during the test.
The control computer of this instrument is designed specifically for voltage breakdown testing machines. Please do not add or delete programs or use them for other purposes at will.
Our company reserves the right to make improvements to the equipment without notifying the user separately.
Note: For any other matters not covered, please feel free to contact us. We will be happy to assist you.
Electricity:/Welcome to call us. We are dedicated to serving you!
Breakdown voltage tester/dielectric breakdown strength tester/withstand voltage breakdown strength tester/insulation material electrical strength tester/dielectric breakdown voltage tester
Meet the standards:
GB1408-2006 GB/T1695-2005 GB/T3333 HG/T3330 /GB12656/ASTM D149. and other standards
1. This instrument can draw real-time curves of the boost breakdown process during the experiment, and the boost curve for each test is composed of different colors,
After the experiment is completed, the repeatability of the experimental data of the comparative materials can be overlaid.
2. You can access current and historical experimental data at any time to view, edit, and modify experimental results.
3. During the experiment, the test conditions and storage path can be modified at any time, and the test results can be automatically stored.
4. During the experiment, the validity of the experiment can be determined at any time through software, facilitating the screening of experimental results.
5. It is possible to set passwords for the software, generate password protection, and enable dedicated personnel to operate it, avoiding unauthorized personnel from making mistakes.
6 The test results can be edited, modified, and printed for easy operation 更加人性化。
7. Can the experimental results of curve data in a set of experiments be manually selected .
8. This instrument adopts a non-contact component constant speed voltage regulation method, eliminating the mechanical transmission boosting method in similar products.
Mainly applicable to solid insulation materials, and can also be measured The breakdown strength of liquids, powders, and irregular objects. Automatic plastic surgery The testing accuracy is the same as that of solids.
Simultaneously measuring the breakdown strength and withstand voltage strength of AC voltage and DC voltage at the power frequency Test for setting gradient withstand voltage Allow the gradient time to be freely adjusted.
This instrument is controlled by a PC and completed through our company's independently developed new intelligent digital precision embedded Siemens central unit CPU system and upper computer software control,
Through PC USB Serial port obtains data and transfers data up to a maximum of 3M/S is RS232 serial port * Enable communication between the upper computer and the lower computer without delay to achieve a truly uniform and accurate boost rate, and enable accurate measurement of leakage current data, with real-time current acquisition.
Real time drawing of experimental curves, display of experimental data, accurate judgment, and the ability to save, analyze, print, and modify experimental data.
And extract experimental data for color comparison. Clearly humanized
Introduction to experimental software:
The appearance of this device software is designed by professional graphic designers:
Personnel management: Multiple people can be added to use this software simultaneously Different personnel set different passwords Cross use without interfering with each other If one person uses it, the password can be deleted Directly enter the software)
Parameter management:
High voltage protection is optional
Voltage endurance time is optional
Gradient step optional 、
Leakage current and overvoltage are optional
Sensitive leakage voltage options
Leakage current optional 、
The boost speed can be freely set (0-50kv) Infinite Freedom)
Test results are optional
Remote operation selection 、
Selection of human-machine separation, etc
Result retrieval:
Save and retrieve test results 、
Personnel selection and retrieval
The test results can be organized and operated according to customer requirements 、
Support more than 5 color line comparisons
Automatically collect and add experimental data.
Equipment safety instructions:
1. The equipment needs to be equipped with a separate protective grounding wire.
Grounding protection is mainly used to reduce the strong electromagnetic interference caused by the breakdown of the sample to the surrounding area. It can also prevent the computer from losing control.
2. The circuit of the experimental equipment is equipped with multiple protective measures,
There are mainly overcurrent protection, voltage loss protection, leakage protection, short circuit protection, DC test discharge alarm, etc.
3. Grounding requirements: The instrument needs to be grounded separately, in accordance with national standards, and the metal rod should be buried at least 1.5 meters deep underground.
4. The circuit of the experimental equipment is equipped with multiple protective measures,
There are mainly overcurrent protection, voltage loss protection, leakage protection, short circuit protection, DC test discharge alarm, etc.
technical indicators：
01. Input voltage: communication 220 V
02. Output voltage: communication 0--50 KV ; direct current 0—50 KV
03. Electrical Capacity: 5KVA
04. High voltage classification: 0-50KV，
05. Boosting rate: 0.1-5.0kv (freely filled in)
(Note: Meets standard requirements and can set different boost rates according to user needs)
06. Test method:
DC test: 1. Constant speed boost 2. Gradient boost 3. Voltage withstand test
Communication test: 1. Constant speed boosting 2. Gradient boosting 3. Voltage withstand test
07. Test medium: air, test oil
08. Install a highly sensitive overcurrent protection device to ensure that the power is cut off within 0.05 seconds when the sample breaks down.
09. Instrument equipped with * fault alarm system Prevent users from operating faulty instruments and causing danger. (Upper computer alarm and lower computer alarm)
10. Support short circuit test requirements in a short period of time.
11. Voltage test accuracy: ≤ 1%.
12. Continuous adjustable test voltage: 0--100 KV。
13. Current can be collected to m* And achieve Real time collection.
14. Provide a calibration certificate for measurement units or a certificate for customer measurement units
15. Power supply: 220V ± 10% single-phase AC voltage and 50Hz ± 1% frequency
16. Current and voltage stability: external voltage fluctuation of 10% (Optional to be equipped with our company's voltage protector) Rated fluctuation voltage 30%)
17. Boosting device: using non-contact components to uniformly boost voltage, eliminating the previous mechanical voltage regulation
18. Voltage endurance time: 0-6H to maintain relative voltage (Software settings)
19. Breakdown sample: breakdown point of the sample The adjustable size is generally around 1-5mm
20. Oil bath with easy disassembly and assembly (can be customized according to customer needs, or oil bath can be omitted)
21. Chassis material: SUS304 stainless steel
22. Support human-machine separation for remote operations .
23. Control mode: optional PC /EPC
24. Communication method: Adopting the most advanced technology in the country, wireless Bluetooth control, supporting 232/USB/Asia Pacific regional network port.
Switching between AC and DC tests
1) The high voltage output of this instrument is AC voltage. The method of obtaining direct current is to string a high-voltage silicon stack into the original circuit, making the test circuit a pulsating direct current voltage. The implementation process is that the silicon stack is already in the high-voltage insulation tower of the high-voltage transformer, and a short-circuit rod is usually used to short-circuit the high-voltage silicon stack. When a DC test is required, remove the short-circuit rod and connect the high-voltage silicon stack to the test circuit. At this time, the voltage in the circuit is a pulsating DC voltage.
2) Front panel DC/AC selection button. The status of this button cannot change the voltage properties of the device output. Pressing this button will simply connect the DC alarm circuit to the device. Instruct the user that when opening the box door, you need to discharge the high-voltage equalizing ball. Rotate the discharge pole so that the copper ball at the end of the discharge pole contacts the high-voltage equalizing ball. It is recommended that users keep the copper ball in contact with the high-voltage equalizing ball for more than five seconds each time they discharge.
3) The switching of AC/DC voltage in the experiment mainly depends on whether the short-circuit rod in the high-voltage insulation tower is removed. When the short-circuit rod is removed, the voltage on the high-voltage equalizing ball is DC voltage, and when the short-circuit rod is inserted, the voltage on the high-voltage equalizing ball is AC voltage. Refer to the schematic diagram on the left for the removal and insertion of the short-circuit rod.
4) In DC testing, the computer should also choose the DC state, otherwise the measured results will be incorrect. Simply put, there is a multiple relationship between AC voltage and DC voltage.
The standard model is:
BDJC-10KV
BDJC-20KV
BDJC-30KV
BDJC-50KV
BDJC-100KV
BDJC-150KV
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Voltage breakdown?
Electronic devices have the highest withstand voltage value they can withstand. If the allowable value is exceeded, there is a risk of device failure. The forms of failure of active and passive components are slightly different, but both have a permissible upper voltage limit. Transistor components all have a withstand voltage value, exceeding which can cause damage to the components, such as diodes, capacitors, etc. If the voltage exceeds the withstand voltage value of the components, it can cause them to break down. If the energy is high, it can cause thermal breakdown and the components will be scrapped.
Dielectric breakdown?
It refers to a non-conductive substance added between two conductive plates for certain purposes. Due to high voltage, this substance is broken, loses its non-conductive function, and becomes a conductor. This phenomenon is dielectric breakdown.
The simplest and most common medium is air. If the voltage is high, air will ionize.
Insulation strength?
The ability of insulation itself to withstand voltage. When the voltage applied to the insulation exceeds a certain critical value, the insulation will be damaged and lose its insulation function.
Usually, the insulation strength of power equipment is expressed in terms of breakdown voltage; The insulation strength of insulating materials is represented by the average breakdown electric field strength, abbreviated as breakdown field strength. The breakdown field strength refers to the voltage at which breakdown occurs under specified test conditions divided by the distance between the two electrodes to which the voltage is applied. The insulation strength is usually determined by testing. The insulation strength varies fundamentally depending on the type of insulation used.
Internal insulation?
Insulation inside electrical equipment. Insulation including solid media, liquid media, or gas media, as well as composite insulation composed of different media. The external atmospheric conditions have little effect on the internal insulation. However, factors such as material aging, high temperature, continuous heating, and moisture have adverse effects on the insulation strength of internal insulation. If the internal insulation breaks down, generally speaking, its insulation strength cannot be restored on its own.
External insulation?
Various forms of insulation for electrical equipment operating in direct contact with the atmosphere. Including exposed surfaces of air gaps and solid insulation of electrical equipment. After the discharge stops, the insulation strength of the external insulation can usually quickly recover and is independent of the number of repeated discharges. The insulation strength of external insulation is closely related to external atmospheric conditions. insulation strength
The development of surface discharge at the interface between solid insulation and air into penetrating air breakdown is called flashover. The voltage value required to cause flashover on the outer insulation surface under certain experimental conditions is called the critical flashover strength.
The volt second characteristic refers to the relationship curve between the impulse discharge voltage of insulation and the corresponding discharge time under the premise of a certain impulse voltage waveform. It is determined by experimentation. Used in engineering to represent the breakdown characteristics of insulation under impulse voltage.
The insulation strength of external insulation is closely related to external atmospheric conditions, and is influenced by various factors such as atmospheric temperature, pressure, humidity, and dirt conditions. The Electrical Commission stipulates that the standard atmospheric state is: atmospheric pressure1013Millibars（1Ba=105Pa),temperature20℃, humidity11gram/The conversion method between external insulation discharge voltages under different atmospheric conditions is specified, with a capacity of 1.3 meters. The measured voltage values under non-standard atmospheric conditions should be converted to the voltage values under standard atmospheric conditions; On the contrary, when applying voltage values under standard atmospheric conditions, they should be converted to voltage values under atmospheric conditions during testing or operation.
Critical flashover strength?
The development of surface discharge at the interface between solid insulation and air into penetrating air breakdown is called flashover. The voltage value required to cause flashover on the outer insulation surface under certain experimental conditions is called the critical flashover strength. Sometimes the flashover strength is represented by the average flashover field strength. It refers to the quotient obtained by dividing the voltage at which flashover occurs by the leakage distance along the interface of two media or the vertical distance between two electrodes under specified test conditions. The experimental conditions are divided into several categories, including dry state, rainy state, and dirty state. The critical flashover strengths obtained in these states are referred to as dry flashover strength, wet flashover strength, and dirty flashover strength, respectively. Due to the uneven voltage distribution at the interface of the medium, the flashover voltage along the surface is lower than the breakdown voltage when gas or solid exists alone. The flashover voltage is lower in the rainy state than in the dry state, and the flashover voltage along the surface will decrease more significantly in humid and dirty conditions.
Voltage second characteristic?
Electrical equipment insulation not only bears the long-term working voltage, but also the transient overvoltage. Overvoltage can be divided into two categories. One type is overvoltage caused by lightning strikes on equipment or induced by lightning strikes near equipment; Another type is overvoltage caused by operations, accidents, or resonances in the power system. The duration of overvoltage is short, but the value of overvoltage greatly exceeds the normal operating voltage.
The development of discharge requires a certain amount of time, and under the continuous voltage, the discharge delay has no effect on the discharge voltage; However, for short duration impulse voltages, the impact of discharge delay cannot be ignored. In engineering, the volt second characteristic is used to represent the breakdown characteristics of insulation under impulse voltage. The volt second characteristic refers to the relationship curve between the impulse discharge voltage of insulation and the corresponding discharge time under the premise of a certain impulse voltage waveform.
The volt second characteristic is determined by experiments, and the method is to keep the waveform of the impulse voltage unchanged and gradually increase the voltage. When the voltage is low, breakdown occurs at the tail of the wave; When the voltage is very high, the discharge time is reduced to a very small amount,Breakdown can occur at the wave head. When the wave tail hits through, take the amplitude of the impulse voltage as the vertical axis and the discharge time as the horizontal axis. During the breakdown of the wave head,The discharge time is also taken as the horizontal axis, but the voltage at breakdown is taken as the vertical axis. The time required to complete discharge is shorter at higher voltages and longer at lower voltages.
Electrical strength?
Electrical strength testing, also known as withstand voltage testing. Simply put, any electrical equipment has an insulation level, and the insulation level varies depending on the rated voltage. When the voltage level exceeds a certain threshold, the insulation of the equipment will be broken down. Electrical strength testing is to apply a certain high voltage (referring to IEC standards or national standards) to the tested equipment to see if it will cause breakdown. If it does not break through, it passes; if it breaks through, it indicates that it is unqualified.
Usually, this test is conducted before the equipment leaves the factory, and on site, it may only be necessary to shake the insulation. In addition, this test is a destructive test, and once it breaks down, it cannot be repaired.
Electrical strength testing, also known as withstand voltage testing, is a process that focuses on the characteristics of insulation materials that exhibit conductor properties after being broken down. It examines the changes in relevant electrical parameters to determine whether the insulation material has been broken down.
Content and testing tools?
Gas dielectric breakdown under power frequency AC voltage. In a uniform electric field (see non-uniform electric field))In the gap, the power frequency breakdown voltage and the DC breakdown voltage are equal. In gaps with extremely uneven electric fields (such as rod plate gaps), breakdown always occurs when the rod electrode is in a positive polarity state, so the amplitude of the AC breakdown voltage is similar to the DC breakdown voltage of the positive polarity rod to the negative polarity plate gap. The average AC breakdown field strength of the rod plate air gap isEа≈4.8kV/cm, compared to the aboveE+Very close. In order to provide design basis for the air gap distance of high-voltage transmission lines or substations, many people have studied the power frequency breakdown voltage of long air gaps in recent years(Strong gap breakdown). Picture2for1～10mBreakdown voltage curve of gap distance. in the picture,curve1、2It's great-The gap between the rod electrode and the upper rod electrode is5mThe lower electrodes are respectively6mand3mThe breakdown voltage of the two is slightly different. This is because of the curve2The electrode of the lower rod is short, and the influence of the earth is significant. curve3It's great-Breakdown voltage of ground gap,It's better than awesome-The value of rod gap is much lower,and there is“saturation”The trend. These experiments were conducted indoors and later demonstrated by outdoor experiments, but no such incidents occurred“saturation”Phenomenon.“The phenomenon of saturation is caused by the influence of laboratory walls. Conducting long gap experiments requires a large laboratory and a significant investment. Therefore, many people are studying the use of theoretical models or experimental simulations to replace actual size experiments.
Solid dielectric breakdown?
The lowest critical voltage that causes breakdown is called the breakdown voltage In a uniform electric field,The ratio of breakdown voltage to dielectric thickness is called breakdown electric field strength (referred to as breakdown field strength),Also known as dielectric strength).It reflects the electrical strength of the solid dielectric itself.In an uneven electric field,The ratio of breakdown voltage to the thickness of the dielectric at the breakdown point is called the average breakdown field strength,It is lower than the dielectric strength of solid media in a uniform electric field.After solid dielectric breakdown,Due to the large current passing through,Molten or burnt channels may appear in the medium,Or cracks may appear.When brittle media breakdown occurs,Frequent material fragmentation occursBased on this, non-metallic ores can be broken
There are three forms of solid dielectric breakdown:Electric shock penetrationThermal breakdown and electrochemical breakdown
Electric breakdown is caused by the accumulation of a sufficient number and energy of charged particles in a dielectric due to an electric field, resulting in the loss of insulation properties of the dielectric Thermal breakdown is caused by the action of an electric field,Accumulation of heat inside the dielectric,High temperature leads to loss of insulation ability.Electrochemical breakdown occurs in an electric field,Under the influence of temperature and other factors,Slow chemical changes occur in dielectrics,Performance gradually deteriorates,Zui ultimately loses its insulation ability.The chemical changes in solid dielectrics typically increase their conductivity,This will cause the temperature of the medium to rise,Therefore, the ultimate form of electrochemical breakdown is thermal breakdown.The impact of temperature and voltage duration on electrical breakdown is minimal,Has a significant impact on thermal breakdown and electrochemical breakdown;The influence of local non-uniformity of electric field on thermal breakdown is smallIt has a significant impact on the other two types
Liquid dielectric breakdown?
The breakdown mechanisms of pure liquid dielectrics and engineering liquid dielectrics containing impurities are different For the former, there are mainly theories of electrical breakdown and bubble breakdown,There is a gas bridge breakdown theory for the latter.The discharge phenomenon along the interface between liquid and solid dielectrics is called surface discharge in liquid dielectrics.This discharge not only causes the liquid to deteriorate,Moreover, the thermal effect and drastic pressure changes generated by discharge may cause bubbles to form inside the solid medium.Multiple actions can cause stratification in solid media,Cracking phenomenon,Discharge may develop within solid media,The breakdown voltage of the insulation structure decreases as a result.When liquid dielectric breakdown occurs under pulsed voltage,Frequent occurrence of strong gas shock waves (i.e. electric water hammer),Can be used for underwater explorationBridge pier inspection and extracorporeal fragmentation of human visceral stones
Gas dielectric breakdown?
Under the action of an electric field, gas molecules undergo collisional ionization, resulting in penetrating discharge between electrodes There are many influencing factors,Mainly applicable voltage,Electric board shape,The properties and states of gases, etc.Common gas dielectric breakdown methods include direct current voltage breakdown,Power frequency voltage breakdown,High pressure electrical breakdown,Impulse voltage breakdown,High vacuum electrical breakdown,Negative gas breakdown, etc.Air is a great gas insulation material,High ionization field strength and breakdown field strength,Can quickly restore insulation performance after breakdown,And non combustible,Not explosive,Not aging,Non-corrosive,Therefore, it has been widely used.To provide the design basis for the air gap distance of high-voltage transmission lines or substations (such as how high the high-voltage transmission lines should be above the ground)A power frequency breakdown test with a long air gap is required
Development trend?
The insulation withstand voltage test is divided into two types: DC withstand voltage test and AC withstand voltage test. In the past, DC voltage withstand test was used for cable voltage withstand test. Research and practice have shown that the DC withstand voltage test is ineffective and harmful to rubber insulation. China began researching and practicing voltage withstand testing technology in the 1990s. After more than 20 years of research and practice, countries around the world have adopted AC withstand voltage testing instead of DC withstand voltage testing. Domestic and foreign standard organizations have also made changes and revisions to the testing methods for high-voltage cables.1997yearCIGRIThe working conference on the power grid raised doubts about the current DC withstand voltage test method and recommended the use of AC test methods with power frequency and approximate power frequency (30-300HZ), which should be promoted and applied within the scope of *. China's North China Electric Power Group, Guangdong, Jiangsu, Zhejiang, Fujian, Anhui and other power grids have successively issued the "Test Regulations", which mandate the use of AC withstand voltage test instead of DC withstand voltage test. In provinces with relatively developed power grids in China, AC withstand voltage testing has become a mandatory standard. Experimental protocols for other regions are also being drafted and developed. The replacement of traditional DC withstand voltage test with AC withstand voltage test is the trend.