Sunday, May 23, 2010

Classification of cables

Classification of cables:-

4 - 1Classification of cables: cables are usually classified according to the voltage for which they are manufactured accordingly they are classified as:
* Low voltage cables, up to and including 1000 volts.
* Medium voltage cables, starting 2000 volts up to and including 33kv.
* High voltage cables, above 33kv up to and including 150kv.
* Extra high voltage cables, 220kv, 400kv and 500kv.

4 - 2 Requirements for the cables: the followings are the necessary items required for the cables:
-the copper or aluminum conductor should be of correct size suitable for the cable to carry the specified load without overheating the cable, and giving voltage drop within the limits.
-the cores of the cable must have the proper insulation thickness to give high reliability and safety at the voltage for which it is designed.
-the cable must have a mechanical protection so as to withstand the worst conditions of laying and installations.
-all materials used in manufacturing the cable should be stable chemically and physically through out the cable life.