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265

Bull. Earthq. Res. Inst.

Univ. Tokyo

Vol. pp.

* e-mail : [email protected]

Earth Watch - Safety Net Research Center, Chubu University

Earthquake Prediction Research Center, Tokai University

Tokyo Electric Power Co., Inc.

We propose a new monitoring system by using the neutral current of transformers at substa-

tions of an electric power company named “neutral current monitoring”. It means that we have

been measuring the telluric field by using the power line system in order to monitor the electromag-

netic state of the underground over an extended time period. The principle of this system is as

follow : the neutral points of the transformers in the substations are grounded to the earth and

power lines connect them. If the neutral points of the transformers correspond to the grounded

electrodes and the power line between substations corresponds to the electric wire between the

electrodes, we can observe the telluric field and change of the electromagnetic structure of the

underground between substations by measuring the current which flows at the neutral point of the

transformer to some extent.

We found that the neutral current is a ected by various factors such as the geomagnetic

changes and artificial noises like as the conventional telluric field observations. We would be able

to investigate the underground electric conductivities near the substations by calculated response

function between geomagnetic field data and neutral current data.

: neutral current of transformers, telluric field observation, geomagnetic variation

Jun Izutsu , Makoto Harada , Takeshi Terayama , Tomiichi Uetake and Toshiyasu Nagao *

*

Abstract

Key words

A Preliminary Report

An Approach of the Continuous Electrical State Moni-toring by Using the Ground Wire of Neutral Point atExtra-high Voltage Substations

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272

GIC No.

Uyeshima, M., , EM Monitoring of Crustal Processes In-

.

Izutsu, J., T. Ochi, T. Uetake and T. Mutakamihigashi, The

relationship between the current through the trans-

former neutral point and natural phenomena, IEEJ

Transactions on Fundamentals and Materials, ,

No. , , .

Lundby, S., B.E. Chapel, D.H. Boteler, T. Watanabe, and R.E.

Horita, , Occurrence Frequency of Geomagnetically

Induced Currents : A Case Study on a B.C. Hydro kV

Power Line, Journal of Geomagnetism and Geoelectric-

ity, , .

:

.

.

Albertson, V.D., J.M. Thorson Jr. and S.A. Miske Jr., ,

The E ects of Geomagnetic Storms on Electrical Power

Systems, IEEE Transactions on Power Apparatus and

Systems, , No. , . .Allen, J., L. Frank, H. Saver, and P. Reif, , E ects of the Tanbo, T., Nagao, T. and Sakai, H., , Geoelectromagnetic

March Solar Activity, EOS, , No. , . study using the leak current from railroad as a signal.Boteler, D.H., R. J. Pirjola and H. Nevanlinna, , The Application to Ohtawa Station, Gifu Prefecture, Ja-

E ects of Geomagnetic Disturbances on Electrical Sys- pan , Proc. Japan Acad., , Ser. B, .tems at the Earth’s Surface, Advances in Space Re-

search, , No. , .

Harada, M., Hattori, K. and Isezaki, N. : ”Transfer Function .Approach to Signal Discrimination of ULF Geomag-

netic Data”, Phys. Chem. Earth, , pp. , . cluding the Use of the Network-MT Observations, Surv.

Geophys, , , DOI . /s - - -x.HV- - .

.

Received June ,

Accepted February ,

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