Abstract: Apparatus for directly monitoring the conductor temperature or other parameters of an energized electric power line conductor, or of the medium adjacent the conductor, on a real time basis, and transmitting a signal indicative of that parameter to a remote location such as to facilitate data processing by computer. The apparatus is powered by the electric or electromagnetic field of the electric power line conductor.Various embodiments are described for sensing the temperature or other parameter being monitored. Furthermore two techniques are described for transmitting the signal to a remote location. The first such technique is the use of air as the transmission medium and the second technique uses the power line conductor itself as the transmission medium.