Super Tension (S.T.) Cables

 In solid type cables separate arrangement for avoiding void formation and increasing dielectric strength is not provided. Hence those cables are used maximum upto 66 kV level. The S.T. cables are intended for 132 kV to 275 kV voltage levels.

       In such cables, the following methods are specially used to eliminate the possibility of void formation :

1. Instead of solid type insulation, low viscosity oils under pressure is used for impregnation. The channels are used for oil circulation and oil is always kept under pressure. The pressure eliminates completely, the formation of voids.

2. Using inert gas at high pressure in between the lead sheath and dielectric.

      Such cables using oil or gas under pressure are called pressure cables and are of two types,

       a. Oil filled cables    b. Gas Pressure cables