Optical ground wire

Abstract: A magneto-optical sensor, using a dual quadrature polarimetric processing scheme, was evaluated for current metering and protection applications in high voltage lines. Sensor calibration and resolution were obtained in different operational conditions using illumination in the 1550-nm band. Results obtained indicated the feasibility of interrogating such sensor via the optical ground wire (OPGW) link installed in standard high power grids. The polarimetric bulk optical current sensor also was theoretically studied, and the effects of different sources of error considering practical deployment were evaluated. In particular, the interference from external magnetic fields in a tree-phase system was analyzed.

Abstract: A splice closure apparatus for a multi-layer combination ground and fiber optic cable, commonly called an optical ground cable, includes a weather impervious outer cylinder made of an impact and corrosion resistant material. The cylinder is open at both ends and is designed to hold a splicing assembly including a pair of sealing end caps, one for each end of the cylinder. Each end cap includes an elastomeric sealing material sandwiched between two rigid plates bolted together with the bolts extending through the elastomeric material. When the end cap bolts are tightened, the elastomeric material is expanded outward to sealingly engage the outer cylinder. At least one of the end caps includes cable through bores through which cables to be spliced are introduced into the splicing assembly and closure and each of the end cap plates include four cable slots leading from the outside thereof to respective cable through holes in the elastomeric layer. The elastomeric layer is segmented such that a pair of outer sections between respective slot pairs are removable and a pair of outer and inner cable clamps are separable such that a continuous multi-layer cable can be inserted and securely anchored without the need to first sever the cable.

Abstract: Round-trip transmission delays in a 128.5-km optical ground wire (OPGW) link and 12.5-km and 12-km overhead fiber-optic cable links were measured to clarify the effect of meteorological conditions, dominantly atmospheric temperature, on the delay variation. Transmission delays measured at 5 a.m. can be well expressed only in terms of atmospheric temperature along the links, while those at 1 p.m. can be expressed using four meteorological parameters of atmospheric temperature, sunshine duration or solar radiation, wind speed and precipitation. The coefficients of delay variation with respect to atmospheric temperature range approximately from 60 to 100 ps/km//spl deg/C where the cable links are more affected by temperature than the OPGW link, and delays in the daytime vary more than in the nighttime due to solar radiation. The results could be used for estimating the increase of cable temperature due to solar radiation and for designing fiber-optic time transfer networks effective for power system protection.