Application of the Global Positioning System to the measurement of overhead power transmission conductor sag

This paper describes a method to directly measure the physical sag of overhead electric power transmission conductors. The method used relies on the Global Positioning System (GPS) used in the differential mode. The direct measurement of sag is a main advantage of the concept. The digital signal processing required is described in detail in a four-level configuration. The typical accuracy, response time, problems, strengths and weaknesses of the method are also described.