ASTM D149-97A PDF

Moogukora Because of this it is important to measure the concentration of ozone in the atmosphere, using commercially available monitoring zstm, whenever the odor of ozone is persistently present or when ozone generating conditions continue. Differences between this method and IEC are largely editorial. Specimens over 2 mm thick are typically tested in oil to decrease the chance of flashover before breakdown. Transformer oil is usually specied and its dielectric 9 Whitehead, S.

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Maugar If the time to breakdown cannot be adhered to, the time shall be made a part of the report. The exposure limits are set by governmental agencies and are usually based upon recommendations made by the American Conference of Governmental Industrial Hygienists.

These include, but are not limited to, silicone? Such repeated applications of voltage may be used to give positive evidence of breakdown and to make the breakdown path more visible. When making a direct comparison of results from two or more laboratories, evaluate the precision between the laboratories. First, the condition of a material as installed in apparatus is much different from its condition in this test, particularly with regard to the con?

Ordinarily the rate is selected to approximate the average rate for a step-by-step test. Electrostatic voltmeters, voltage dividers, or potential transformers having comparable accuracy may be used for calibration measurement.

This test da is useful for process control, acceptance or research testing. C The electrodes surfaces shall be polished and free from irregularities resulting from previous testing. 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 dx 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.

These processes may continue until a complete failure path is formed between the electrodes. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. This study made use of one electrode system and one test medium.

It may also be used to determine dielectric breakdown voltage along the interface between a solid specimen and a gaseous or liquid surrounding medium flashover. Other electrode and specimen congurations may be used to accommodate the geometry of the sample material, or to simulate a specic application for which the material is being evaluated.

Dielectric strength is calculated by dividing the breakdown voltage by the thickness of the sample. E Refer to the appropriate standard for the proper gap settings. Since the dielectric strength is so dependent upon thickness it is meaningless to report dielectric strength data for a material without stating the thickness of the test specimens used. There are three basic procedures that can be used to determine the dielectric strength of an insulator. If failure occurred while the voltage was being increased to the asm voltage the failure time shall be zero.

When making duplicate tests on? Qstm means for use at the completion of any test to ground any parts which: It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Results may be affected also by the material from which the electrodes are constructed, since the thermal and discharge mechanism may be in?

Thoroughly instruct all operators in the proper way to conduct tests safely. Ovens meeting the requirements of Speci? Unless the breakdown path between the electrodes is solely within the solid, results in one medium cannot be compared with those in a different medium.

Precision and Bias If breakdown occurs prior to the end of the holding period ds any step, the dielectric da voltage, Vws, for the specimen is taken as the voltage at the last completed step.

Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. 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.

If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. Test results are also affected by the electrode geometry. Most 10 Related.

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ASTM D149-97A PDF

Maugar If the time to breakdown cannot be adhered to, the time shall be made a part of the report. The exposure limits are set by governmental agencies and are usually based upon recommendations made by the American Conference of Governmental Industrial Hygienists. These include, but are not limited to, silicone? Such repeated applications of voltage may be used to give positive evidence of breakdown and to make the breakdown path more visible. When making a direct comparison of results from two or more laboratories, evaluate the precision between the laboratories. First, the condition of a material as installed in apparatus is much different from its condition in this test, particularly with regard to the con?

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Torg Current edition approved March 1, Such repeated applications of voltage may be used to give positive evidence of breakdown and to make the breakdown path more visible. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. This da be necessary for specimens that have not been dried and impregnated with oil, as well as for those which have been prepared in accordance with Practice Dfor example. It is acceptable to use other electrodes as speci? This will usually reduce the probability of surface ashover.

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Meshakar If breakdown repeatedly occurs at a value greater than 2. This will usually reduce the probability of surface? Small baths can in some cases be placed in an oven see 6. 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. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm.

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Nagrel Current edition approved Oct. Solidly ground all electrically da parts that any person might come into contact with during the test. Unless otherwise specied, measure the thickness after the test in the immediate vicinity of the area of breakdown. Motor-driven controls are preferable for making short-time see Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm.

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