Issues associated with GSM installations on power line towers

摘要

In recent years, power line towers havernbeen increasingly used for the installation of mobilerntelecommunication stations and antennae (‘GSM’).rnSuch additions to the power network have raised manyrnquestions related to the earthing arrangements of therntwo systems; these effects include the effect of faultrncurrent level, step and touch potentials in the vicinityrnof the structures and transferred potentials to thernfeeding lower voltage circuits. In this paper, arncomprehensive study of the chain impedance ofrn275kV and 400kV tower lines is presented. Both d.c.rnAnd 50Hz a.c. conditions are examined and the effectrnof line length and variations in soil resistivityrnquantified. The calculated impedance of operationalrntower lines is compared with results obtained fromrnfield tests. The study was extended to consider faultrnconditions on an interconnected transmission linernsystem in order to evaluate the rise of earth potentialrnat tower bases. Finally, step and touch voltages werernevaluated for worse case conditions. Comparativernstudies including the GSM station were alsornconducted.