Zero phase current measurements at neutral earth of transformer by EM propagation for possible earthquake prediction

The VAN method of measuring telluric current has resulted in successful earthquake prediction. Such experiments in Japan and abroad, have revealed electromagnetic variations in the earth depending on crust distortion stress. Building a large-scale extensive information-processing network of observation points may enable detection of abnormal telluric current and spatial electromagnetic waves as signs of earthquakes. Successful detection should improve prediction reliability. In substations, located at both ends of a long-distance power transmission line, the electric power company grounds the neutral earth lines of the three-phase transformers in order to protect the power transmission system and to prevent injury to workers. The power transmission line, the earth, and the neutral earth lines of transformers compose a large loop circuit. Measurements were made to assist the detection of the telluric current that circulates deep in the earth. An impulse generator (IG) was used as an artificial lightning generator to input pulse current to the earth. A simulated transformer earth line was tested for electromagnetic-wave detection. It has been reported that at 300 kHz or less, electromagnetic waves are transmitted through the transformer neutral earth line without damping. We estimate that seismic information can be obtained from the transformer neutral earth line. If electromagnetic waves emit from the surface or topsoil, it is possible to locate the electromagnetic wave source from its arrival time and the difference between the spatial electromagnetic waves and the earth current.