ASTM D149-97A PDF

Buy ASTM Da() Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at. Dielectric Strength ASTM D, IEC Scope: Dielectric Strength is a measure of the electrical strength of a material as an insulator. Dielectric strength is. ASTM DA – Designation: D – 97a (Reapproved ) An American National Standard Standa.

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If dissimilar electrodes are used such as Type 6 of Table 1 and only one surface is to be machined, the larger of the two electrodes shall be in contact with the machined surface. A number in parentheses indicates the year of last reapproval.

The nature of the insulating liquid and the degree of previous use may inuence 4 the test values. A number in parentheses indicates the year of last reapproval. Use appropriate means, such as exhaust vents, to reduce ozone concentrations to acceptable levels in working areas. Link to Active This link will always route to the current Active version of the standard. However, even materials that absorb little or no moisture may be affected because of greatly increased chemical effects of discharge in the presence of moisture.

If prolonged current follows breakdown it will result in unnecessary burning of the test specimens, pitting of the electrodes, and contamination of any liquid surrounding medium. Active view current version of standard. For such materials, the conditioning shall be included in the standard referencing this test method.

A number of different physical arrangements of voltage source, measuring equipment, baths or ovens, and electrodes are possible, but it is essential that 1 all gates or doors providing access to spaces in which there are electrically energized parts be interlocked to shut off the voltage source when opened; 2 clearances are sufficiently large that the eld in the area of the electrodes and specimen are not distorted and that ashovers and partial discharges corona do not occur except between the test electrodes; and 3 insertion and replacement of specimens between tests be as simple and convenient as possible.

Some of these effects can be incorporated in laboratory tests, and a better estimate of the material will result, but the? Second, in service there are deteriorating inuences, heat, mechanical stress, corona and its products, contaminants, and so forth, which may reduce the breakdown voltage far below its value as originally installed.

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The optimum current setting is not the same for all specimens and depending upon the intended use of the material and the purpose of the test, it is often desirable to make tests on a given sample at 3 more than one current setting. Whitehead10 that in order to avoid discharges in the surrounding medium prior to reaching the breakdown voltage of the solid test specimen, in alternating voltage tests it is necessary that Em?

Test results are also affected by the electrode geometry.

This technique is of particular value for research testing. For most materials, using electrodes similar to aetm shown in Table 1, an output current capacity of 40 mA is usually satisfactory.

Link to Active This link will always route to the current Active version of the standard. Molecular Structure and Electrical Behavior, Vol.

Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.

Molecular Structure and Electrical Behavior, Vol. It is acceptable to use other electrodes as speci?

Dielectric Strength ASTM D, IEC

In addition to the dielectric breakdown voltage, mentioned above, particulate contaminants are especially important when very thin specimens 25? This standard has been approved for use by agencies of the Department of Defense. Because of this it is important to measure the concentration of ozone in the atmosphere, using commercially available monitoring devices, whenever the odor of ozone is persistently present or when ozone generating conditions continue.

Differences between this method and IEC are largely editorial. Do not use another document, including those listed in this appendix, as a model for reference to this test method unless there is conformity with 5. References to this document should specify the particular options to be used see 5. D-7, Glenway Ave.

It shall have a dielectric breakdown voltage as determined by Test Method D of at least 26 kV. The dielectric withstand strength is to be calculated from the thickness and the dielectric withstand voltage, Vws.

Ovens meeting the requirements of Specication D and provided with means for introducing the test voltage will be suitable for use when only temperature is to be controlled. The material of the gaskets or seals around the electrodes has the potential to in?

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Dielectric Strength ASTM D149, IEC 60243

Repeated applications of voltage will sometimes result in failure at lower voltages sometimes unmeasurably lowusually with additional damage at the breakdown area. Use the short-time test unless otherwise speci?

Solidly ground all electrically conductive parts that any person might come into contact with during the test. In general, the dielectric strength will decrease with increasing temperatures, but the extent to which this is true depends upon the material under test.

This test method is useful for process control, acceptance or research testing. This standard does not purport to address all of the safety concerns, if any, associated with its use. If failure occurs at the third step or less, or in less than s, whichever is greater, on more than one specimen in ast, group, repeat the tests with a lower initial voltage.

Repeated applications of voltage will sometimes result in failure d149-97 lower voltages sometimes unmeasurably lowusually with additional damage at the breakdown area. This is to be expected because the thermal breakdown mechanism is time-dependent and the discharge mechanism is usually time-dependent, although in some cases the latter mechanism may cause rapid failure by producing critically high local eld intensitives.

Unless otherwise specied the upper electrodes shall be 50 6 2 g. B Electrodes are normally made from either brass or stainless steel. The power rating for most tests will vary from 0. When making duplicate tests on?

Some of these effects can be incorporated in laboratory tests, and a better estimate of the material will result, but the nal consideration must always be that of the performance of the material in actual service.

They astj less critical as to concentricity of the electrodes than are the Types 1 and 2 electrodes. E Refer to the appropriate standard for the proper gap settings. The test values are dependent upon specimen asym, electrodes, and other variable factors, in addition to the properties of the sample, so that it is not possible to make a statement of bias.

References to this document should specify the particular options to be used see 5.

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