HV Switch Gear

A pure insulator when is connected across line and earth, it behaves as a capacitor and the capacitive electric current always leads the applied voltage by 90o. In practice, due to the aging of insulators, the impurities like dirt and the presence of the moisture in the insulators, the insulator cannot be made 100% pure. Those things provide the conductive path to the current. Consequently, an electric leakage current flowing from line to earth throughout the insulator has a resistive component.

Hence, the healthiness of an electrical insulator can be determined by the ratio of the resistive component to the capacitive component which this ratio commonly known as tan δ or tan delta and sometimes referred as dissipation factor. We perform this test for all insulated electrical equipment. For instance;

• Power Transformer & Bushings
• Cable
• Rotating Machine
• Outdoor Switchyard HV Equipment
– CTs, Capacitive VTs, Inductive VTs, Surge Arresters and Circuit Breakers