The size of the electronic and electrical equipment is decreasing day by day bringing in the need of wires of smaller size so that they can be accommodated in reduced space in the equipment. In high voltage applications if size of conductor is reduced the corona (ionized discharge) is produced. This corona attacks the insulation and greatly reduces the life of insulating material. Hence to avoid the damage of insulation the conductor size has to be kept big which in turn limits the miniaturization process of the equipment. High voltage corona resistant (HVCR) cables remove this problem.
These cables are made by insulating the conductor with specially made corona resistant (CR) PTFE tape. CR PTFE tape has increased resistance to corona discharge which helps in making high voltage cables in reduced sizes.
The HVCR cables are available for voltages as high as 22 KV AC or 50 KV DC both with screen and without screen. Screened HVCR cables are recommended where electrical circuit in proximity of HVCR cable needs to be protected from corona..
In the wiring of electronic equipments used for transmission of electronic signals, it is observed that the signals get disturbed by external electric and electromagnetic noises produced by equipment, motors etc in close proximity with the wire which results in poor transmitted signal quality.
This problem is tackled by shielding/screening the equipment with a metal wire braid or aluminum/mylar tape serv shield or both and then finally covering it with protective jacket. The Shield is grounded and this helps in keeping the signals inside the inner conductor to be protected from outside noises. Single core shielded wires are available in various sizes generally ranging from 0.5 Sq mm to 4.0 Sq mm and above.