ASTM D149-2009 dielectric breakdown voltage test method

ASTM D149-2009 dielectric breakdown voltage test method

Breakdown voltage of solid electrical insulating materials at industrial frequencies

And standard test method for insulation strength 1

This standard is issued under the fixed code D149. Subsequent figures indicate the year in which the original text was formally adopted; in the case of revisions, the last revised year number; the number in parentheses is the last reconfirmed year number. The superscript symbol (ε) indicates an edit modification to the last modified or redefined version.

This standard has been approved for adoption by the Department of Defense.

Voltage withstand breakdown tester 1. Scope

1.1 This test method covers the process of determining the dielectric strength of solid insulating materials at industrial frequencies, ie under specified specific conditions. 2,3

1.2 Unless otherwise stated, the specified frequency for this test is 60 Hz. However, this test method can also be applied to conditions of 25 to 800 Hz. If the frequency is greater than 800 Hz, then the problem of media heating will occur.

1.3 This test method will be used in conjunction with other ASTM standards or other standards related to the test method. The specific criteria used are detailed in the references to this method (see 5.5).

1.4 The method can be applied to a variety of temperatures, as well as suitable gaseous or liquid phase environmental media.

1.5 This method cannot be used to determine insulation materials that are liquid under the test conditions.

1.6 This method cannot be used to determine intrinsic insulation strength, DC insulation strength, or thermal failure under electrical stress conditions (Reference Test Method D3151).

1.7 This test method is most commonly used to determine the relationship between breakdown voltage and sample thickness (breakdown). The relationship between the breakdown voltage and the surface condition of the solid sample and the medium in the gas phase or liquid phase (flashover) can also be determined. This test method can also be used to verify the test if the modification of Article 12 is added.

1.8 This test method is similar to the 243-1 standard published by the International Electrotechnical Commission (IEC). All processes in this method are included in the IEC 243-1 standard. This method and IEC 243-1 are mainly different in editing.

1.9 This standard does not fully enumerate all safety statements and, if necessary, based on actual usage. Before using this specification, it is the responsibility of the user to establish regulations and specifications that meet safety and health requirements and to clarify the scope of use of the specification. The specific hazards will be addressed in Section 7. See also section 6.4.1.

ASTM D149-2009 dielectric breakdown voltage test method

Voltage withstand breakdown tester 2. References

2.1ASTM standard: 4

D374 Test method for thickness of solid electrical insulators (cancelled in 2013) 5

D618 Test Regulating Plastic Operating Procedures

Standard Test Method for Dielectric Breakdown Voltage of Electrically Insulating Liquids Using Disc Electrodes

D1711 Electrical insulation related terminology

D2413 Preparation of insulating paper and paperboard impregnated with liquid medium

D3151 Test method for thermal failure of solid electrical insulating materials under electrical stress (cancelled in 2007) 5

D3487 Standard Specification for Mineral Insulating Oils Used in Electrical Equipment

D5423 Specification for electrical insulation evaluation in forced convection test furnaces

2.2 IEC standard

Methods of test for dielectric strength of solid insulating materials - Part 1 : Tests at industrial frequencies 6

2.3 ANSI standard

C68.1 Insulation Testing Technology, IEEE Standard No. 47

1 This test method is directly responsible for the D09.12 branch (electrical test) within the jurisdiction of ASTM Committee D09 (Electronic and Electrical Insulation Materials).

This version was approved on April 1, 2013 and published in April 2013. The first edition was approved in 1922. The previous edition was approved for D149-09 in 2009. DOI: 10.1520/D0149-09R13.

2 Bartnikas, R., Chapter 3, "High Voltage Measurements," Electrical Properties of Solid Insulation, Measurement Techniques, Volume IIB, Engineering Dielectrics, R. Bartnikas, Editor, ASTM STP 926, ASTM, Philadelphia, 1987.

3Nelson, JK, Chapter 5, “Solid Dielectric Breakdown,” Electrical Properties of Solid Insulation: Molecular Structure and Electrical Behavior, IIA?, Engineering Dielectric, R. Bartnikas and RM Eichorn, Editors, ASTM STP 783, ASTM, Philadelphia, 1983.

4 For reference to the ASTM standard, please see the ASTM website. . Org, or contact the ASTM Customer Center, email:. For information on the ASTM standard volume, see the standard document excerpt page on the ASTM website.

5 The latest approved version of this historical standard is available on the website. . Org.

6 available from the International Electrotechnical Association (IEC), address: 3 rue deVarembé, Case postale 131, CH-1211, Geneva 20, Switzerland, http://.

7 Available from the American National Standards Institute (ANSI) at 25 W. 43rd St., 4th Floor, New York, NY 10036, http://. . Org.

ASTM D149-2009 dielectric breakdown voltage test method

Voltage withstand breakdown tester 3. Terminology

3.1 Definition:

3.1.1 Dielectric breakdown voltage (electric breakdown voltage), noun: The potential difference that causes the dielectric material between the two electrodes to lose dielectric properties (see Appendix X1).

3.1.1.1 Discussion A dielectric breakdown voltage is sometimes referred to as "breakdown voltage".

3.1.2 Dielectric failure (in testing), noun: refers to the situation that can be prolonged by the rise of dielectric conductivity under the electric field conditions under test limits.

3.1.3 Insulation strength, noun: refers to the voltage gradient when the dielectric material fails under the specific conditions of the test.

3.1.4 Electrical strength, noun: see insulation strength.

3.1.4.1 Discussion One is “electrical strength” more commonly used internationally.

3.1.5 flashover, noun: refers to the destructive electrical spark that occurs in the medium surrounding the insulator or insulator, and does not necessarily cause permanent damage to the insulator.

3.1.6 For definitions of other terms related to solid insulator materials, see the term D1711.

Voltage withstand breakdown tester 4. Test method summary

4.1 Under industrial electrical frequency conditions (60 Hz unless otherwise specified), different voltages are applied to the test samples. In one of the three methods described using the voltage, the voltage is raised from 0 or from an appropriate voltage below the breakdown voltage, and rises until the test sample undergoes dielectric failure.

4.2 In most cases, a simple test electrode is mounted on both sides of the test sample for voltage testing. Test samples can be molded, cast, or cut from flat sheets or slabs. Other electrodes or sample structures can also be used to accommodate the geometry of the sample material or to simulate the particular use of the material being evaluated.

ASTM D149-2009 dielectric breakdown voltage test method

Voltage withstand breakdown tester 5. Meaning and use

5.1 The dielectric strength of electrical insulation is a key property that determines the conditions under which a material can be used. In many cases, the dielectric strength of a material is a decisive factor in the design of the device used.

5.2 The tests described in this method will be used to provide some of the required information to determine the suitability of the material under certain application conditions; of course, it can also be used to detect changes in process, degree of aging, or other manufacturing or Changes caused by environmental conditions or deviations from normal characteristics. This test method can be effectively applied to process control, verification or research testing.

5.3 The results obtained by this test method are rarely directly used for the judgment of the dielectric properties of the actual materials used. In most cases, other functional tests and/or results from other material tests need to be compared to estimate their impact on a particular material before they can be evaluated.

5.4 The three voltage usage methods will be specified in Chapter 12. Method A, rapid test; method B, stepwise test; method C, slow test. Method A is often used for quality control testing. The more time consuming methods B and C generally give lower results, but the results given are more convincing when comparing different materials to each other. If an electric voltage controller can be installed, the slow test method will be simpler and more common than the step-by-step test method. The results obtained by methods B and C can be compared to each other.

5.5 Detailed description of the test method is as follows:

5.5.1 Method of voltage application.

5.5.2 If it is a slow test method, the voltage increase rate should be stated.

5.5.3 Selection, preparation and adjustment of test samples.

5.5.4 Environmental media and temperature during testing.

5.5.5 Electrode.

5.5.6 where possible, the standard for failure of current sensing components, and,

5.5.7 and any deviation from the recommended process.

5.6 If the requirements listed in 5.5 do not appear in the documentation, they can be treated as follows.

5.7 If the items listed in 5.5 are not specified, then the test is performed under insufficient conditions and the test does not meet the requirements of this method. If the entries listed in 5.5 are not strictly controlled, the accuracy stated in 15.2 and 15.3 cannot be achieved.

5.8 Changes in current sensor component failure criteria (current setting and reaction time) will significantly affect the test results.

5.9 Appendix X1 contains a more detailed discussion of the significance of the insulation strength test.

ASTM D149-2009 dielectric breakdown voltage test method

Withstand voltage breakdown tester 6. Device

6.1 Voltage Source—The test voltage is supplied by a varying sinusoidal low voltage power supply through a step-up transformer. The transformer as a voltage source and associated controls shall have the following functions:

6.1.1 The ratio of the voltage peak to the voltage rms value should be equal to (1.34 to 1.48), for test samples in the circuit, all voltages should be greater than 50% of the breakdown voltage.

6.1.2 The voltage should have the ability to maintain the breakdown voltage. For most materials, using an electrode similar to the one shown in Table 1, the output current intensity is 40 mA. For more complex electrode structures, or for high loss test materials, higher currents are required. For most tests, the power supply needs to be tested in a low-capacitance range of 0.5kVA, 10kV to 5kVA, and 100kV.

Table 1 Typical electrode A for insulation strength testing of different insulating materials

Electrode type

Electrode description B, C

Insulation Materials

1

The reverse column has a diameter of 51mm (2in) and a rounded edge of 25mm (1in).

Radius 6.4mm (0.25in)

Flat paper, film, fabric, rubber, plastic, composite, wood, glass, mica and ceramic

2

The reverse column has a diameter of 25mm (1in) and a rounded edge of 25mm (1in).

Radius 3.2mm (0.125in)

Same as Type 1, especially for glass, mica, plastics and ceramics

3

Reverse column diameter 6.4mm (0.25in), round side diameter 0.8mm

(0.313in)D

Same as Type 1, especially for paints, plastics, and other films and tapes: especially small samples that require smaller electrodes, or samples that require small area measurements

4

The plate is 6.4mm (0.25in) wide and 108mm (4.25in) long. The flat ends are 3.2mm (0.125in).

Same as Type 1, especially rubber tape and other narrow sheet materials

5

Hemispherical electrode diameter 12.7mm (0.5in)E

Filling and handling compounds, colloidal and semi-solid compounds and greases, encapsulating, sealing and compressing materials

6

Reverse column: a low diameter of 75mm (3in), 15mm (0.6in)

Thick and high one with a diameter of 25mm (1in) and 25mm thick. Both sides have a radius of 3mm (0.12in)F.

Same as 1 and 2

7

Reverse cycle plate, diameter 150mmG, 10mm thick, radius of the round edge is 3 to 5mmH

Flat, thick, or plate material, the voltage gradients tested are parallel to the surface

A In the ASTM standard, these electrodes are most often specified or referenced. Except for the Type 5 electrode, it is not recommended to use the electrode for materials other than planar materials. Other electrodes specified by ASTM or approved by both buyers and sellers but not listed in this table are also suitable for evaluation of the measured material.

The B electrode is usually made of brass or stainless steel. Reference should be made to the criteria for controlling the material being tested to determine if the material is suitable.

The surface of the C electrode should be polished and the debris left by the last test should be removed.

D Refer to the appropriate standard to determine the load force of the upper electrode installed. Unless otherwise stated, the upper electrode should weigh 50 ± 2g.

E refers to the appropriate criteria to determine the gradient of the appropriate spacing.

A type 6 electrode is given in FIEC Publication 243-1 to determine the plate material. For the concentricity of the electrodes, they are not as important as the Type 1 and Type 2 electrodes.

G Other diameters may be used as long as the inner diameter of the rounded edge of the test sample is greater than 15 mm.

The H7 type electrode, the electrode described in Note G, is given by IEC Publication 243-1 and should be parallel and surface measured.

ASTM D149-2009 dielectric breakdown voltage test method

6.1.3 According to 12.2, the control of the variable low voltage source can change the pressure of the power supply so that the synthesized test voltage is smooth, uniform, and there is no excess or transient. In any environment, the peak voltage is not allowed to exceed 1.48 times the effective value of the display voltage. The motor drive controller is more suitable for quick tests (see 12.2.1) or slow tests (see 12.2.3).

6.1.4 Install a disconnecting device that can be operated in three cycles on the power supply. The device cuts off the voltage source device and the power device to protect the voltage source from the overload of the device caused by sample breakdown. If a continuous current is maintained after rupture, it will cause unnecessary burning of the test sample, pitting the electrode and contaminating the liquid environment medium.

6.1.5 The breaking device shall have a detecting element on the secondary step-up transformer that can adjust the current to adjust and align according to the nature of the test sample to detect the test current. The sensing element is set to handle the test sample breakdown current as defined in 12.3.

6.1.6 Current setting has a significant impact on the test results. The setting should be high enough that a brief voltage, such as a partial discharge, cannot pass through the circuit breaker, and if it is not high enough, it will strike the test sample that burns and burn the electrode. The optimized current setting does not apply to all test samples. Depending on the specific use of the material and the purpose of the test, it is necessary to test the test sample with multiple current settings. The electrode area has a major influence on the setting of the current.

6.1.7 The test sample current sensing element shall be located at the front end of the step-up transformer. Calibrate the current detection scale according to the test sample current.

6.1.8 Care should be taken to set the current control response. If the control is set too high, no response will occur when the breakdown occurs. If set too low, it will respond to leakage current, capacitor current or partial discharge current (corona), or to the magnetizing current of the step-up transformer when the sensing element is at the front end.

6.2 Voltage Measurement—The voltmeter is provided to determine the rms value of the test voltage. The reading should be divided by the voltmeter that can read the peak It is a valid value. The overall error of the voltage measurement circuit must not exceed 5% of the measured value. In addition, no matter what speed is used, the lag rate of the voltmeter response time must not exceed 1% of the whole process.

6.2.1 Measure the voltage by connecting a voltmeter or potential transformer to the test sample electrode or to a separate voltmeter coil on the transformer. The latter connection will not affect the load of the step-up transformer.

6.2.2 The maximum readable voltage of the voltmeter is required to be greater than the breakdown voltage in order to be able to accurately read and record the breakdown voltage.

6.3 Electrodes - For a given test-like structure, the breakdown voltage will still vary considerably due to the geometry of the test electrode and the mounting location. For this reason, it is important to specify the electrode used when specifying this test method and to include it in the report.

6.3.1 The electrodes listed in Table 1 are detailed in the documentation of this test method. If the electrode is not specified, the appropriate electrode should be selected from Table 1, or other electrodes approved by both parties should be used if the standard electrode cannot be used due to the nature or structure of the material being tested. For examples of some special electrodes, see Appendix X2. In either case, the electrode used should be stated in the report.

6.3.2 The entire plane of the Type 1 to Type 4 and Type 6 electrodes in Table 1 shall be in contact with the test sample.

6.3.3 The test sample using the 7-type electrode test shall be in the electrode during the test, and the distance to the edge of the electrode shall not be less than 15 mm. In most cases, when using a Type 7 electrode for testing, the electrode surface should be in a vertical position. The test for placing the electrodes horizontally cannot be directly compared to the test for placing the electrodes vertically, especially for tests conducted in liquid phase environmental media.

6.3.4 Keep the electrode surface clean and smooth and remove any debris left by previous tests. If the electrode surface is rough, the electrode should be replaced in time.

6.3.5 The initial production of the counter electrode and subsequent surface resurfacing should maintain the specific structure and finish of the electrode, which is very important. The flatness and surface finish of the electrode surface should ensure that the entire area of ​​the electrode is in intimate contact with the test sample. Surface finish is especially important when testing very thin materials because the improper surface of the electrode can cause physical damage to the test material. When the surface is rebuilt, the transition between the electrode surface and the specific edge radius cannot be changed.

6.3.6 Regardless of the size or shape, the electrode at the lowest stress concentration, usually the larger one with the largest radius, should have a ground potential.

6.3.7 In some specific liquid phase metal electrodes, electrode foils, metal spheres, water or conductive coating electrodes will be used. It should be recognized that this creates a large difference between the results obtained and the results obtained with other types of electrodes.

6.3.8 Due to the influence of the electrodes on the test results, some additional information is often obtained, so that multiple electrodes need to be tested to understand the insulation properties of a material (or a group of materials). This is especially valuable for research testing.

6.4 Environmental Media—The documentation for this test method shall state the environmental media and test temperature. In order to avoid flashover and minimize the effects of partial discharge before breakdown, even for rapid testing, it should be more or even necessary to test in the insulating fluid (see 6.4.1). The breakdown value obtained in the insulating liquid cannot be compared with the value obtained in the air. The nature of the insulating fluid and the extent of the previous use will also affect the results of the test. In some cases, testing in the air requires a large number of test samples, or can cause severe surface discharge and ablation before breakdown. Some electrode systems tested in air should be covered with pressure pads around the electrodes to prevent flashover. The material of the gasket or seal around the electrode will affect the breakdown voltage value.

6.4.1 If testing in insulating oil, an oil sump of the appropriate size shall be provided. (Note - Glass containers are not recommended for test voltages above 10kV because the energy released by the breakdown is sufficient to break the container. The metal pool must be grounded).

It is recommended to use mineral oil that meets Type I or Type II of Standard D3487. According to the results measured by Test Method D877, the breakdown voltage is at least 26 kV. Other insulating fluids can also be used as environmental media if otherwise stated. These insulating oils include silicone oil and other liquids for transformers, circuit breakers, capacitors or cables, but are not limited thereto.

6.4.1.1 The properties of the insulating oil have a certain influence on the test results. As mentioned above, in addition to the breakdown voltage, contaminants are especially important when testing thinner (less than 25 μm (thousandths of a inch) test samples). Depending on the nature of the oil and test materials, other characteristics such as dissolved gas content, water content, and oil loss factor all affect the measurement results. Frequent replacement of insulating oil, or the use of filters and other repair equipment, helps to reduce the impact of changes in insulating oil performance on test results.

6.4.1.2 The breakdown values ​​measured from different electrical performance liquids are usually not comparable. (Refer to Xl.4.7) If the test is carried out under conditions other than room temperature, a uniform temperature should be ensured by heating or cooling the liquid. In some cases, the insulation cell can be placed in a heating cabinet (see 6.4.2) to control the temperature. If you want to force the liquid to circulate, prevent air bubbles from entering the liquid. Unless otherwise stated, the test temperature on the electrode should be maintained within ±5 °C. In many cases, it should be stated that the test sample will be tested in insulating oil, which has been immersed in insulating oil and not removed from the insulating oil prior to testing (see Practice D2413). For these materials, the insulation cell shall be designed so that the test sample is not exposed to air prior to testing.

6.4.2 If the air is tested at other ambient temperatures or humidity, the heating box and humidity control room should be prepared. The heating box should meet the requirements of the D5423 standard and ensure that the test voltage is suitable for the temperature used.

6.4.3 In addition to air, testing in other gases also requires the use of control rooms that can be excluded or filled with test gases, which typically also control pressure. The design of the control room is determined by the nature of the test project being performed.

6.5 Test Room—The test room or test area in which the test is performed shall have sufficient space to accommodate the test equipment and be equipped with interlocking equipment to prevent access to any live parts. Voltage sources, measuring equipment, cells or heating boxes, and many different physical arrangements of electrodes are possible, but three are necessary. (1) All doors or doors that come in and out of live parts must be interlocked so that Cut off the voltage source when starting the test; (2) Remove as much as possible so that there is no distortion between the electrode surface and the test sample, no flashover and partial discharge (corona) between the test electrodes; and (3) The insertion and replacement of test samples should be as simple and convenient as possible between tests. Electrodes and test samples are often visually tested during testing.

Voltage breakdown tester ASTM D149-2009 dielectric breakdown voltage test method

7. Hazard

7.1 Caution - A fatal voltage will appear in this test. It is necessary to properly design and install the test equipment and all equipment that is electrically connected to it for safe operation. Conductive parts that are in contact with anyone during the test should be placed securely on the ground. When the test is completed, the components that should be placed on the ground include: (a) components under high voltage conditions during the test, (b) components that are inductively charged during the test, or (c) even when disconnected from the voltage A component that still has a charge after the source is connected. Guide all operators to conduct tests safely and in an appropriate manner. When performing high pressure tests, especially when compressed gas or in oil, the energy generated by the breakdown is sufficient to cause a fire, explosion or crack in the test chamber. Design test equipment, test rooms and test samples to reduce the likelihood of such accidents and eliminate the possibility of casualties.

7.2 Warning - At high concentrations, ozone will endanger physical health. The ozone exposure limit is set by the government, which is usually based on the recommendations of the US Government Industrial Hygienist Conference 8. The voltage is high enough to be in the air or other oxygen

8 Available from the American Government Industrial Hygienists Conference (ACGIH) at 1330 Kemper Meadow Dr., Cincinnati, OH 45240, http://. . Org.

Ozone is produced when a partial or complete discharge occurs in the atmosphere of the gas. At low concentrations, ozone has a special smell.

However, continuous inhalation of ozone can cause temporary loss of consciousness of ozone. Because of this, it is important to use industrial monitoring equipment to measure the concentration of ozone in the atmosphere when ozone odors continue to occur or when ozone is always present. Appropriate methods, such as venting, can reduce the concentration of ozone in the work area to an acceptable level.

Voltage breakdown tester

8. Sampling

8.1 A detailed sampling procedure should be defined in the description of the material.

8.2 For the purpose of quality control, sufficient samples should be collected during sampling to evaluate the average quality of the sample to be tested and the change of the tested batch. In order to prevent the sample from being affected by time, it should be in the laboratory or other tests. The area has been sampled when it is ready to test the sample.

8.3 In order to obtain the most desirable test conditions, it is necessary to take samples from areas that are far from obvious defects or discontinuities in the material. For coils, unless additional investigations or proximity to defects or discontinuities are to be investigated, the outer layers should be avoided, such as the outermost layer of the coil package or the material adjacent to the edge of the sheet or roll.

8.4 Sampling should be large enough to allow for individual testing as required by special materials (see 12.4).

Voltage breakdown tester ASTM D149-2009 dielectric breakdown voltage test method

9. Test sample

9.1 Preparation and processing:

9.1.1 Prepare test samples from selected samples as required by Chapter 8.

9.1.2 If a smooth surface electrode is to be used, the surface of the test sample in contact with the electrode should have as smooth a parallel surface as possible without actual surface processing.

9.1.3 The test sample should be of sufficient size to prevent flashover from occurring during the test. For thin materials, using a test sample large enough will allow multiple tests on a single test sample.

9.1.4 For thicker materials (usually above 2 mm thick), there should be sufficient dielectric strength to cause flashover or strong surface partial discharge (corona) before breakdown. Techniques for preventing flashover or reducing partial discharge (corona) include:

9.1.4.1 While testing, immerse the test sample in insulating oil. The effect of environmental media factors on breakdown is given in X1.4.7. This is usually necessary for test samples that are not dry and immersed in oil and those that are prepared in accordance with D2413 procedures (see 6.4).

9.1.4.2 Make a groove on one or both sides of the test or drill a flat bottom hole to reduce the thickness of the test. If different electrodes (such as the type 6 electrode in Table 1) are used, then only one surface needs to be machined and the larger of the two electrodes should be connected to the finished surface. Be careful when processing test samples to avoid contamination or mechanical damage to the test sample.

9.1.4.3 Use a seal or fairing to surround the electrode connected to the test sample to reduce the occurrence of flashover.

9.1.5 Uneven materials shall be tested using test samples (and electrodes) that are similar in sample material and geometry. It is necessary to determine the test samples and electrodes used for these materials as described in the material.

9.1.6 Regardless of the shape of the material, if additional tests are to be performed in addition to testing the face-to-face breakdown strength, the test samples and electrodes used shall be indicated in the description of the material.

9.2 In almost all cases, the actual thickness of the test sample is important. Unless otherwise stated, the thickness of the vicinity of the breakdown point should be measured after testing. Measurements should be taken at room temperature (25 ± 5 ° C) and appropriate procedures should be followed according to the D374 test method.

Voltage withstand breakdown tester 10. Calibration

10.1 When calibrating measurements, the test sample shall be in the path state and note the electrode voltages measured with the accuracy given in 6.2.

10.2 Connect an independent calibration voltmeter to the output of the test voltage source to detect the accuracy of the measurement equipment. Examples of such voltages that are suitable for calibration measurements are: electrode voltmeters with comparable accuracy, voltage dividers, or voltage transformers.

10.3 When the voltage is greater than the effective value of 12kV (16.9kV peak), the reading of the ball gap calibration voltage measuring device is applied. The subsequent process for this calibration is detailed in ANSI C68.1.

ASTM D149-2009 dielectric breakdown voltage test method

Voltage breakdown tester

11. Adjustment

11.1 The breakdown strength of most solid insulators is affected by temperature and humidity. Therefore, prior to testing, the materials affected by this application are balanced with controlled temperature and relative humidity. For this material, adjustments should be included in the standards referenced to this test method.

11.2 Unless otherwise stated. Otherwise, the follow-up process should be carried out in accordance with the D618 operating procedures.

11.3 For many materials, the effect of humidity on breakdown strength is greater than the effect of temperature. The material is adjusted for a sufficient period of time to allow the test sample to simultaneously achieve a balance of humidity and temperature.

11.4 If the condensed water appears on the surface of the test sample during the adjustment, the surface of the test sample should be dried before testing. This usually reduces the possibility of surface flashover.

Voltage breakdown tester

12. Process

12.1 (Note: See Chapter 7 before starting any tests.)

12.2 Method of voltage use:

12.2.1 Method A, Rapid Test Method—As shown in Figure 1, a uniform voltage is applied to the test electrode at a certain boost rate from zero to breakdown. The quick test method will be used unless otherwise stated.

12.2.1.1 When determining the supercharging speed, in order to include the speed increase in the new specified value, for a given test sample, the speed of the breakdown will occur within 10 to 20 seconds. In some cases, it is necessary to perform 1 to 2 pre-tests to determine the speed increase. For most materials, a speed increase of 500V/s is used.

12.2.1.2 If the document refers to the growth rate specified by this test method, then even if the breakdown time occasionally appears outside the range of 10 to 20 s, it should continue to be used. If this happens, the number of failures should be recorded in the report.

rate

(V/s) ±20%

100

200

500

1000

2000

5000

Figure 1 Fast test method voltage diagram

12.2.1.3 If a series of tests are to be performed to compare different materials, the same growth rate should be used, keeping the average time between 10 and 20 s. If the breakdown time cannot be maintained within this range, it should be stated in the report.

12.2.2 Method B, Step-by-Step Test - Apply a suitable starting voltage to the test electrode and gradually increase the voltage as shown in Figure 2 until a breakdown occurs.

12.2.2.1 From the table listed in Figure 2, the starting voltage Vs can be chosen. In the fast test, this voltage should be close to 50% of the test or expected breakdown voltage.

12.2.2.2 If the starting voltage is lower than the voltage listed in Figure 2, it is recommended to use 10% of the starting voltage as the step-by-step voltage.

12.2.2.3 In the absence of the voltage peaks specified in 6.1.3, the starting voltage shall rise from zero as soon as possible. The same requirements apply to the increase in voltage between adjacent steps. After the initial step is completed, the time required to raise the voltage to the adjacent step should be counted in the time of the adjacent step.

12.2.2.4 If a breakdown occurs during the process of raising the voltage to the next step, the test sample has a withstand voltage Vws which should be equal to the voltage of the completed step. If the breakdown occurs before the end of any step duration, the withstand voltage Vws of the test sample is calculated as the voltage of the last completed step. The breakdown voltage Vbd is used to calculate the dielectric strength. The dielectric strength is calculated from the thickness and the withstand voltage Vws. (See Figure 2)

12.2.2.5 requires 4 breakdowns in 10 steps over a period of 120 s. If there are multiple test samples in a group with fewer than 3 times of breakdown, or if the time is less than 120s, the initial pressure should be reduced and retested. If no breakdown occurs before step 12 or after 720 s, the starting voltage should be increased.

12.2.2.6 Record the starting voltage, the number of steps to increase the voltage, the breakdown voltage and the length of time the breakdown voltage lasts. If the failure occurs when the voltage has just increased to the starting voltage, the dead time is zero.

12.2.2.7 Other time lengths relating to the number of voltage steps shall be stated for the purpose of the test. It is usually used for a length of 20s to 300s (5 minutes). For research, it is necessary in some cases to test a given material for a length greater than the normal length of time.

12.2.3 Method C, Slow Test - Apply a starting voltage to the test electrode and increase the voltage as shown in Figure 3 until a breakdown occurs.

12.2.3.1 Select the starting voltage from the slow test specified in 12.2.1. The starting voltage chosen should meet the requirements of 12.2.2.3.

12.2.3.2 Increase the voltage at a certain voltage increase rate starting from the starting voltage specified in the document relating to this test method. In general, the selected rate of increase should be similar to the average rate of increase in the step-by-step test.

12.2.3.3 If a group of multiple test samples breaks down within less than 120 s, then the starting voltage should be reduced or the growth rate should be reduced, or reduced at the same time.

12.2.3.4 If there are multiple test samples in a group with a breakdown voltage less than 1.5 times the initial voltage, the starting voltage should be reduced. If breakdown occurs at a voltage greater than 2.5 times the initial voltage (and after 120 s), the breakdown voltage should increase and the starting voltage should be increased.

A suitable starting voltage, Vs is 0.25, 0.50, 1, 2, 5, 10, 20, 50 and 100 kV, respectively.

Step voltage

in case

Vs(kV)A is

increments

(kV)

Less than 5

Greater than 5 is less than 10

Greater than 10 is less than 25

Greater than 25 is less than 50

Greater than 50 less than 100

Greater than 100

10% of Vs

0.50

1

2

5

10

AVs = 0.5 (Vbd for slow test) unless the parameters specified by the system are not met.

System specified parameters

(t1-t0)=(t2-t1)=...=(60±5)s

Alternate step time. (20±3)s and (300±10)s

120s ≤ tbd ≤ 720s, 60 seconds per step

Figure 2 Step-by-step test voltage diagram

Growth rate (V/s) ± 20%

System specified parameters

1

Tbd>120s

2

5

10

Vbd=>1.5Vs

12.5

20

25

50

100

Figure 3 Schematic diagram of slow test voltage

ASTM D149-2009 dielectric breakdown voltage test method

12.3 Standards for breakdown - dielectric failure or breakdown (as defined in the D1711 terminology) includes increased conductance to limit the maintenance of the electric field. In the test, the phenomenon can be clearly judged by visual inspection and breaking sound across the thickness of the test sample. Test samples were observed to be broken down and broken down in the breakdown area. Such breakdowns are usually an irreversible process. Repetitive voltages can sometimes cause breakdown at low voltages (sometimes below measurable values) and other damage in the breakdown area. This type of reusable voltage often leads to positive evidence of breakdown, which makes the path of breakdown more visible.

12.3.1 In some cases, a rapid increase in leakage current will cause the voltage source to trip without leaving any visible damage on the test sample. This type of failure, usually associated with slow testing at high temperatures, can cause reversible results, and if the test sample is cooled to its initial test temperature before reapplying the voltage, the dielectric strength can be restored. For such failures, the voltage source will be disconnected at relatively low current conditions.

12.3.2在某些场合，由于闪络，局部放电，高电容测试样中的无功电流或是断路器的故障问题都会造成电压源的断开。测试中的此类间断不会造成击穿（除了闪络测试外），而发生此类间断的测试也不能视为满意的测试。

12.3.3如果断路器设置的电流太高，或是如果断路器的故障存在问题，将会造成测试样的过度燃烧。

12.4测试的数量——对于特定材料，除非另有说明，否则应进行5次击穿。

ASTM D149-2009介电击穿电压试验方法

耐电压击穿试验仪

13. 计算

13.1对于每次测试而言，击穿时的绝缘强度应以kV/mm或V/mil为单位来计算，对于逐步测试而言，梯度应以未发生击穿的最高电压步骤来计算。

13.2计算平均绝缘强度及标准偏差，或其他变量的测量值

耐电压击穿试验仪14. 报告

14.1报告应包含以下信息：

14.1.1测试样的鉴定。

14.1.2对每一个测试样；

14.1.2.1所测量的厚度，

14.1.2.2能承受的最大电压（对逐步测试而言），

14.1.2.3击穿电压，

14.1.2.4绝缘强度（对逐步测试而言），

14.1.2.5击穿强度，及

14.1.2.6击穿的部位（电极的中心，边缘或外部）。

14.1.3对于每个样品：

14.1.3.1平均电介质承受强度（仅对逐步测试测试样），

14.1.3.2平均电介质击穿强度，

14.1.3.3变量的说明，最好是标准偏差和变化系数。

14.1.3.4测试样的说明，

14.1.3.5调节和测试样的准备，

14.1.3.6环境的温度和相对湿度，

14.1.3.7环境介质，

14.1.3.8测试温度，

14.1.3.9电极的说明，

14.1.3.10电压应用的方法，

14.1.3.11如果指定，电流感应元件的失效标准，及

14.1.3.12测试的日期。

ASTM D149-2009介电击穿电压试验方法

耐电压击穿试验仪

15. 精度和偏差

15.1表2总结了四个实验室和八种材料实验室间研究的结果。该研究采用同一电极体系和同一测试介质。9

15.2单一操作员精度——根据测试材料，试样厚度，电压供给方式以及控制或抑制瞬间电压脉冲的极限，变化常数（标准差除以平均值）在1%到20％之间变化。如果就同一样品的五个测试样进行重复试验，变化常数通常不大于9%。

表2 从四个试验室总结出的绝缘强度数据A

材料

名义厚度

(in.)

绝缘强度（V/mil）

标准偏差

变化常数（%）

平均值

最大值

最小值

聚对苯二甲酸乙二酯

0.001

4606

5330

4100

332

7.2

聚对苯二甲酸乙二酯

0.01

1558

1888

1169

196

12.6

聚氟乙烯丙烯

0.003

3276

3769

2167

333

10.2

聚氟乙烯丙烯

0.005

2530

3040

2140

231

9.1

PETP纤维增强环氧树脂

0.025

956

1071

783

89

9.3

PETP纤维增强环氧树脂

0.060

583

643

494

46

7.9

环氧树脂玻璃钢

0.065

567

635

489

43

7.6

交联聚乙烯

0.044

861

948

729

48

5.6

平均

8.7

A测试样在油中用2型电极进行测试（参见表1）。

15.3多实验室精度——在不同实验室中（或者同一实验室不同设备上）进行测试的精度是变化的。通过使用同一类型的设备，严格控制测试样的准备，电极以及测试流程，单个操作员的精度是近似的。但如果对来自不同实验室的结果进行比较，就必须评估不同实验室的精度。

9支撑数据已经归档在ASTM国际总部中，通过申请研究报告RR:D09-1026可获得这些数据。

15.4如果测试材料，试样厚度，电极结构，或环境介质不同于表1所列，或是测试设备中电流感应元件的击穿标准得不到严格控制，那么将无法达到15.2和15.3中所规定的精度，对于需要测试的材料来说，涉及本测试方法的标准应能确定该材料的精度适用范围。参见5.4~5.8以及6.1.6。

15.5使用特殊的技术和设备、使材料厚度的精度达到0.01in甚至更小。电极不能损坏试样的接触面。准确的测定击穿电压。

15.6偏差——该测试方法不能测定固有绝缘强度。测试结果取决于试样的几何形状，电极和其他可变参数，以及样品的性质，这使得很难描述偏差。

耐电压击穿试验仪

16. 关键词

16.1击穿，击穿电压，校准，击穿标淮，介电击穿电压，介电失效，介电强度，电极，闪络，电源频率，过程控制测试，验证测试，质量控制测试，快速增加，研究测试，取样，慢速，逐步，环境介质，耐压。

附录

（非强制信息）

Xl. 绝缘强度测试的意义

X1.1 介绍

Xl.1.1简要回顾了击穿的三种假定机制，分别是：（1）放电或电晕机制，（2）热机制，以及（3）固有机制，讨论了在原理上对实际电介质产生影响的因素，并对数据的解释提供帮助。击穿机制常常与其他机制相结合，而非单独发挥效用。随后的讨论仅针对固体和半固体材料。

Xl.2 介电击穿的假定机制

X1.2.1由放电造成的击穿——在对工业材料进行的许多测试中，都是由于放电造成了击穿，这通常造成较高的局部场。对于固体材料来说，放电常常发生在环境介质中，因此增加测试的区域将在电极边缘上或外侧产生击穿。放电也会发生在内部出现或生成的一些泡沫或气泡里。这会造成局部的侵蚀或化学分解。这些过程将一直持续到在电极间形成完全的失效通路为止。

X1.2.2热击穿——在置于高强度电场时，在许多材料内的局部路径上会积聚大量的热，这将造成电介质和离子导电性能的损失，进而迅速产生热量，所产生的热量将大于所能耗散掉的热量。由于材料的热不稳定性，导致了击穿的发生。

X1.2.3固有击穿——如果放电或热稳定性都不能造成击穿，那么在电场强度大到足以加速电子穿过材料时，仍将发生击穿。标准电场强度被称为固有绝缘强度。虽然机制本身也许已经涉及，但本测试法仍不能测试固有绝缘强度。

Xl.3 绝缘材料的性质

X1.3.1固态工业绝缘材料通常是非均匀的，且含有许多不同的电介质缺陷。试样上常常发生击穿的区域，并不是那些电场强度最大的区域，有时甚至是那些远离电极的区域。在应力下卷中的薄弱环节有时将决定测试的结果。

X1.4 测试和测试样状况的影响因素

X1.4.1电极——通常，随着电极区域的增加，击穿电压会降低，这种影响对于薄试样来说更为明显。电极的几何形状也会影响测试的结果。制作电极的材料也会对测试结果产生影响，这是因为电极材料的热导性和功函会对热机制和发电机制产生影响。通常来说，由于缺乏相关的实验数据，所以很难确定电极材料的影响。

X1.4.2试样厚度——固体工业绝缘材料的绝缘强度主要取决于试样的厚度。经验显示，对于固体和半固体材料来说，绝缘强度与以试样厚度为分母的分数成反比，更多的证据显示，对于相对均匀的固体来说，绝缘强度与厚度的平方根互为倒数。如果固体试样能熔化后倒入到固定电极之间并凝固下来，那么电极间距的影响将很难得到明确的定义。因为在这种情况下，可以随意固定电极间距，所以习惯在液体或可溶固体中进行绝缘强度测试，此时电极间具有标准的固定空间。因为绝缘强度取决于厚度，所以如果在报告绝缘强度数据时缺乏测试所用试样的起始厚度，那么这样的数据将毫无意义。

X1.4.3温度——试样和环境介质的温度将影响绝缘强度，虽然对于大多数材料来说，微小的环境温度变化对材料造成影响可以忽略不计。通常，绝缘强度随温度的升高而降低，但其强度的极限取决于被测材料。众所周知，由于材料需要室温以外的条件下发挥作用，所以有必要在比期望操作温度更大的范围里，对绝缘强度与温度的关系进行确定。

X1.4.4时间——电压应用的速率也会影响测试结果。通常，击穿电压随电压应用速率的增加而提高。这是预料之中的，因为热击穿机制有赖于时间，而放电机制也有赖于时间，虽然在一些情况下，后一种机制通过产生局部电场高临界强度造成快速失效。

X1.4.5波形——通常，应用电压的波形也会影响绝缘强度。在本测试方法的限制说明中，波形的影响是不显著的。

X1.4.6频率——对于本测试法，在工业用电频率范围内，频率的变化对绝缘强度的影响将不是那么显著。但是，不能从本测试法所得结果中推断出其他非工业用电频率（50到60HHz）对绝缘强度的影响。

X1.4.7环境介质——通常测试具有高击穿电压的固体绝缘材料，是将试样浸入到液体介质中，例如变压器油，硅油，或是氟利昂中，以减小击穿前表面放电的影响。这已经由S.Whitehead10所揭示，为了避免固体试样在达到击穿电压前在环境介质中发生放电现象，在交流电测试中，有必要确保：

（X1.1）

如果浸入的液体介质是一种低损耗材料，该公式可以简化为：

（X1.2）

如果浸入的液体介质是一种半导体材料，那么该公式可以变为：

（X1.3）

式中：

E=绝缘强度；

f=频率；

ε和ε′=介电常数；

D=耗散因数；

o=电导率（S/m）；

下标：

m指浸入介质；

r指相对值；

O指自由空间；

（εO=8.854×10-12F/m）

s指固体电介质。

X1.4.7.1Whitehead指出，要避免表面放电，则应提高Em和εm或是提高σm。通常规定使用变压器油，其介电性能是这样的，如果电场强度Es达到以下水平，则会发生边缘击穿：

（X1.4）

如果测试样很厚，且其介电常数很小，那么含有ts的量将成为相对影响因数，介电常数与电场强度的乘积将近似于一个常数。11Whitehead也指出（p. 261）使用潮湿的半导体油将能有效减少边缘放电的现象。如果电极间的击穿路径仅在固体中出现，那么此介质将不能与其他介质进行比较。也应该注意到如果固体是多孔的或是能够被浸入介质充满，固体的击穿强度将受到浸入介质电气性质的直接影响。

X1.4.8相对湿度——相对湿度影响绝缘强度是因为测试材料吸收的水分或表面吸附的水分将影响介质损耗和表面电导率。因此，它的重要性很大程度上有赖于测试材料的性质。但是，即使材料只吸收了一点甚至没有吸收水分，仍会受到影响，因为在有水的情况下，将大大提高放电的化学效应。除此之外，还应调查暴露在电场强度中的影响，通常通过标准的调节流程来控制或限制相对湿度的影响。

10文献：Whitehead, S., 固体介电击穿, Oxford University Press, 1951.

X1.5 评估

X1.5.1通电设备绝缘的一个基本要求就是它应能承受得住在服务中施加于它的电压。因此很有必要对测试进行评价，以评价处于高压应力条件下的材料性能。介质击穿电压测试是一种测定材料是否需要进一步考察的初步测试，但是它无法就两个重要方面进行全部评估。首先，安装在设备上的材料条件与测试条件大为不同，尤其在考虑了电场结构和暴露在电场中的材料面积，电晕，机械应力，周围介质以及与其他材料的连接之后，更是如此。第二，在服务时，会出现很多恶劣的影响，例如热，机械应力，电晕及其产物，污染物等等，都会使击穿电压远低于最初安装时的击穿电压值。在实验室测试中，可以合并其中的一些影响，进而对该材料做出更准确的估计，但是最终考察的仍然是那些处于实际服务的材料性质。

X1.5.2介质击穿测试能作为材料检测或是质量控制测试，作为一种推测其他条件的手段，例如变率，或是指明恶化的过程，如热老化。在使用本测试法时，击穿电压的相对值比绝对值更重要。

X2. D149测试法所涉及的标准