Testing Equipment:-
1. Testrano 600 Omicron
2. CP TD1 Omicron
Principle of Tan Delta Test:- When a pure insulator is connected between the line and earth, it acts like a capacitor.
Ideally, if the insulating material, also serving as a dielectric, is 100% pure, the electric current passing through would only have a capacitive component, with no resistive component, due to zero impurities.
In a pure capacitor, the capacitive electric current leads the applied voltage by 90°.
In reality, it’s impossible to achieve 100% purity in insulators. Over time, aging insulators accumulate impurities such as dirt and moisture.
These impurities create a conductive path, introducing a resistive component to the leakage current from the line to earth.
Therefore, a low resistive component of leakage current indicates a good insulator.
The health of an electrical insulator is gauged by the low ratio of resistive to capacitive components, known as tan delta or dissipation factor.
Image by fiaz