Tan Delta Testing Determines Insulation Problems

  • Uncategorized

Insulation quality should be tested regularly to determine signs of aging. Impurities, vibration, moisture and electrical stress all contribute to the deterioration of the insulation. The tangent delta is measured and compared to the factory baseline data to detect problems in the insulation.


Tan delta has many applications in testing high voltage insulators like cable insulation, insulating oils and bushings. This allows the engineer to find issues and prevent further deterioration. It allows the engineer to repair the issues and prevent insulation breakdowns.

VLF hipot is used to apply AC current to the conductor and the phase angle loss is measured. An ideal insulator should shift the current at 90 degrees. However, impurities lower the resistance of the insulator. This allows current to directly flow to the tan delta bridge resulting to a lesser phase shift of the current. The lowered resistance can allow high voltages to flow and short out the device.

You can rent equipment for conducting this type of test and other tests from Protec. We have a wide selection of high voltage test equipment to meet your electrical testing needs. Call us at 866-352-5550 and enjoy affordable rental rates on test equipment.