Tan Delta testing is a method of assessing the quality of cable insulation. This allows technicians to determine the cable’s remaining life expectancy and when a cable should be replaced. This test is carried out using a Tan Delta bridge and a high potential tester.
If a cable is free from damages, the insulator and conductor form a perfect capacitor. The central conductor acts as one of the plates and the insulator as the dielectric. Ideally, if you pass an alternating current through a capacitor, the current will be shifted by 90 degrees. However, if there are contaminants like dirt, oil, moisture and other conductive materials, the resistance of the insulator decreases. This allows resistive currents to flow through the insulator and causes a lesser phase shift.
The HV Diagnostics TD30 is a Tan Delta bridge that allows you to measure loss angle in cables. It has a solid-state and battery operated design that allows portable operation. It also comes with an analysis software for enhanced cable insulation diagnostics.