The higher the dielectric strength of a material the better its quality as an insulator. Each of these three methods has the same basic set-up, which consists of the test specimen placed between two electrodes. For the most common test, the short-time method, voltage is applied across the two electrodes and raised from zero to dielectric breakdown at a uniform rate. Breakdown is when an electrical burn-through punctures the sample, or decomposition occurs in the specimen. The test is sometimes performed in oil to prevent arcing from the electrode to the ground.
Dielectric strength is calculated by dividing the breakdown voltage by the thickness of the sample.
A higher dielectric strength represents a better quality of insulator. Links Entire contents 1996-2001 Plastics Technology Laboratories, Inc.