| Popis: |
KESC is an electrical utility company involved in generation, transmission and distribution of electric energy in Karachi, Pakistan. The total number of consumers of KESC to date is around 2.0 million. KESC started installing OPGW for providing data to the SCADA system in 1998 and till year 2006 around 151 km OPGW is installed. These OPGW cables connect the SCADA system to 8 power generating stations including the KESC generation stations and 56 grid stations of IPPs. In the course of testing and monitoring the installed OPGW, it was revealed that the OPGW installed at various transmission lines have been damaged. On close inspection of the samples taken from the damaged OPGW, it is found that the outer OPGW layer was almost melted and strings were broken. The optical fiber cable inside OPGW was also tested with the OTDR and it was also found broken. Therefore, it is concluded that the outer OPGW layer could not stand the voltage introduced due to the lighting strokes. In addition, the distance between the hanging OPGW was not enough to withstand the million of volts and a flash occur between OPGW. In this paper, the selection criteria of OPGW cables based on engineering specification are discussed. This paper also discusses the methods and standardized test procedures for OPGW cables. Finally, the replacement strategy of the conventional ground wire by OPGW is presented. |
