ASTM D149, IEC 60243 Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials

Get Certified ASTM D149 Testing of Solid Electrical Insulating Materials

ASTM D149 is the standard test for the electrical breakdown characteristics of solid insulating materials. The technician prepares the specimens, places them between the appropriate electrodes, applies the required alternating voltage, and records the breakdown voltage and relevant test conditions. The results are used in quality control, material qualification, research, and for comparison with product specifications. If testing is required, then it is essential to verify the qualifications and scope of accreditation of the testing provider.

• Material type: Solid electrical insulating materials, such as appropriate plastics, sheets, films, laminates, etc., and other solid insulation.
• Purpose: Evaluate an insulating material’s ability to withstand electrical stress.
• Properties measured: Dielectric breakdown voltage and dielectric strength.
• Test method: Apply electrical pressure to a specimen of insulating material.
• Result: Breakdown voltage in volts (V) or kilovolts (kV); dielectric strength commonly expressed in kilovolts per millimeter (kV/mm) when calculated using specimen thickness.
• Test conditions: Electrode arrangement, specimen dimensions, surrounding medium, conditioning, and voltage application procedure influence the result.
• Limitations: Results are for the test conditions and do not necessarily reflect long-term electrical endurance or performance of the finished product.

What are the uses of ASTM D149 testing?

The test classifies the material’s recovery capability, a manifestation of its mechanical performance. It may help detect changes in material performance due to the manufacturing process, aging, or the environment. Engineers use the data to gain an understanding of the control process and to compare the performance of various types of insulation under the same test conditions. It is also used for research.

• Electrical insulation quality control: Check consistency of production batches. 
• Selection of materials: Make a comparison of appropriate insulating materials for electrical equipment and components. 
• Product Development: Investigate effects of formulation and process modifications on dielectric properties. 
• Manufacturing verification: Detect deviations related to the process or material aging. 
• Electrical equipment design: Furnish data for insulation design and material qualification. 
• To research and test: Study the failure modes under certain electrical and environmental conditions.

Which Materials Can Be Tested According to ASTM D149?

This method applies to solid electrical insulating materials that can be prepared and tested this way. The material can be tested in a suitable surrounding medium, such as a gas or a liquid, and at certain temperatures. The test can measure breakdown over the thickness of the specimens (puncture) or breakdown in the region between the solid specimen and the medium in which it is embedded (flashover). 

• Electrical laminates: Appropriate laminated insulating boards and sheets. 
• Elastomeric insulation: Solid insulating rubber and other appropriate elastomers. 
• Film and sheet insulation: Specimens prepared to comply with the film and sheet insulation method, and conforming to the dimensional requirements of the method. 
• Composite insulating materials: Appropriate solid insulating composites for the designated electrode structure. 
• Other solid dielectrics: Other solid electrical insulation materials that meet the test requirements.

Why is ASTM D149 testing important?

Electrical insulating material must withstand electrical stress without unwanted breakdown. ASTM D149 is a standard to measure the breakdown properties and compare materials under controlled conditions. Manufacturers can use the results to assess material uniformity and qualify their products, but they also need additional functional and application-specific data to predict material performance in actual equipment use. 

ASTM D149 Testing Process and Data Collection

In ASTM D149, technicians prepare and condition specimens, place them between the specified electrodes, and apply alternating voltage in accordance with the selected procedure. They monitor the electrical response until breakdown occurs or until a specified test endpoint. When applicable, we measure breakdown voltages and specimen thicknesses and use them to calculate dielectric strength. Technicians document the sample identification, material type, specimen dimensions, and thickness (mm). Analysts record the voltage application method, test frequency (hertz), medium surrounding the test item, and the test temperature (℃). The breakdown voltage (V or kV) is recorded by the technicians. Furthermore, they determine whether the failure occurred through the specimen or through the specimen’s surface.  The analysts calculate the dielectric strength in kV/mm using the required voltage and thickness, as needed. Record the electrode configuration, equipment information, failure criteria, and any deviations from procedure. The final report contains the ASTM D149 (specimen details), test conditions, individual results, and references to the applicable specification.

Common Challenges and Troubleshooting

The ASTM D149 specification result is dependable only when the sample preparation, the electrode configuration, moisture content, and the application of voltage are under the control of the technician. Repeatability depends on careful setup and consistent procedures. Take measurements at appropriate points throughout the specimen and record any thickness variations which could influence the electric field. Check contact and position of electrodes before applying high voltage. Minimize unwanted effects on breakdown behavior by controlling the condition of specimens and surface cleanliness. Apply the given voltage by the specified method, and ensure the correct rate of rise or step sequence.

• Technicians record the specimen’s identification, material specification, thickness (mm), and preparation information. The analyst reports the dielectric breakdown voltage of each specimen in V or kV. If dielectric strength needs to be determined, evaluators perform the test and report it in kV/mm (kilovolts per mm of specimen thickness) to help estimate breakdown voltage and specimen thickness.
• The technicians document the test frequency, voltage application method, electrode configuration, surrounding medium, and test temperature. Analysts check if the test concluded with puncture versus flashover and make note of any relevant comments. 
• The report includes the ASTM method, specimen details, test conditions, measured values, calculated results, and relevant deviations.
• Engineers evaluate results with appropriate material specifications or other functional test results. They do not rely on any single key failure point to forecast performance over time in actual equipment.

Do you serve international clients for ASTM D149 testing?

Please check with the provider whether international service is available, shipment requirements, and, if appropriate, customs/documentation requirements for samples.

Link to ASTM D149