Lightning protection, earthing and surge protection of base transmission stations
An effective lightning protection design for a telecommunication facility requires an integrated approach to a number of key factors: • Protection against direct lightning strikes • Effective earth termination network for discharge of lightning current • Integration of power supply and lightning protection earthing systems • Extensive equipotential bonding to prevent electric shock • Mitigation for ground potential rise • Prevention of conducted surges to equipment cabin • Mitigation of LEMP This paper examines the challenges and solutions in the integration of lightning protection, earthing and surge protection for a base transmission station comprising a telecom tower and an equipment cabin, taking into consideration external power source via overhead lines.
Lightning Effect on Copper and Optical Fiber (FTTN) Access Networks of Telecommunication Systems
This paper presents a study of lightning effect on copper and optical fiber (fiber to the node) public switched telephone network (PSTN) in Sri Lanka. The study covers, firstly modeling and simulation of each PSTNs, secondly development and testing of PSTN laboratory prototypes and finally a case study for a selected real network. The individual PSTNs were modeled by PSCAD/EMTDC software and were verified in the laboratory by applying lightning surges to the developed prototypes. The study was extended by considering the effects of typical earth resistances in the PSTN and possible multiple reflections. In the case study, first the RLC parameters of the PSTN were estimated by field and laboratory measurements. Then, the PSTN was modeled and analyzed in PSCAD/EMTDC software. It was found that significant components of lightning surges may transfer to the consumer side unless proper surge protective devices are used. Further, this effect may be higher in the optical fiber network compared to the copper network. A significant effect may also appear at the subscriber side due to multiple reflections and the earth resistances characterized by high soil resistivity.
Atmospheric drag effects on the KOMPSAT-1 satellite during geomagnetic superstorms
We examine the atmospheric drag on the low earth-orbiting satellite, KOMPSAT-1 in a sun-synchronous orbit at ~685-km altitude starting in 1999, during a 3-month (October-December) period in 2003. This 3-month interval includes the October 29-30 and November 20 magnetic superstorms and weak to moderate storms. We observed that the daily KOMPSAT-1 drag acceleration transiently responses to transient storm-time disturbances. That is, there is an one-to-one correspondence between the KOMPSAT-1 drag accelerations and the storm events. We find that the drag acceleration correlates strongly with the level of geomagnetic disturbance. This indicates that the trajectory of KOMPSAT-1 is significantly perturbed during extremely disturbed intervals because of atmospheric density increase. The main contributor to the density increase is Joule heating associated with the geomagnetic activity rather than the solar EUV radiation, as reported by previous studies. We suggest that understanding how the upper atmosphere responses to the geomagnetic-associated heating is important to predict space weather impacts on low earth-orbiting satellites.