What is dielectric strength testing?

Dielectric strength is a measure of the electrical strength of a material as an insulator. It is defined as the maximum voltage required to produce a dielectric breakdown through the material and is expressed as 'volts per unit thickness'. As with other polymer material properties, the breakdown voltage is rate-dependent. The test methods account for this with various options within the standards:
  • Rapid rise test with failure occurring within 10-20 seconds
  • Step-by-step test
  • Slow rate of rise
Other factors which can influence the results are the electrode system, test temperature, frequency of the electric field and material thickness. Where possible, tests are carried out in air but it may be necessary to test in oil to prevent flashover.

Dielectric strength standards that Smithers can test to:

  • ASTM D149
  • BS EN 60243-1
For more information on how Smithers can support with dielectric strength testing in our materials testing labs, please contact an expert. 
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