Semiconductor tape

[vinod]

Hai
can you explain the use of "semiconductor" tapes in electrical joints (MV or HV)

 

[don_resqcapt19]

The semi-conductive layer between conductor and insulation which compensates for air voids that exist between conductor and insulation.
Air is a poor insulation, having a nominal dielectric strength of only 76 volts per mil, while most cable insulation have dielectric strengths over 700 volts/mil. Without strand shielding an electrical potential exists that will over-stress these air voids.
As air breaks down or ionizes, it goes into corona (partial discharges). This forms ozone which chemically deteriorates cable insulation. The semi-conductive strand shielding eliminates this potential by simply “shorting out” the air.

Insulation Shield System
The outer shielding which is com-prised of two conductive components: a semi-conductive layer (semi-con) under a metallic layer (see cable types for common shield varieties). The principal functions of the insulation shield system are to:
1. Confine the dielectric field within the cable
2. Obtain a symmetrical radial distribution of voltage stress within the dielectric
3. Protect the cable from induced potentials
4. Limit radio interference
5. Reduce the hazard of shock
6. Provide a ground path for leakage and fault currents.

The cable’s two shielding systems (strand shield and insulation shield system) must be rebuilt when constructing a splice. The same two methods are used as outlined in the reinsulation process: tape and molded rubber.
For a tape splice, the cable strand shielding is replaced by a semiconductive tape. This tape is wrapped over the connector area to smooth the crimp indents and connector edges.

All of the above is from this 3M document.
Don

 

[vinod]

thanks

thanks

thanks Mr. Don for your information