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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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Fig. . The conceptual figure of the measurement of
the current by the power line system.
km km
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Fig. . The figure shows the daily variations of the neutral current observed at the Higashi Yamanashi substation
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Fig. . The neutral currents at each substation and the electric potential di erences at Atsugi station observed
from June , to June , . The geomagnetic variation at Kakioka, the temperature and rain fall at
Atsugi station are also shown.
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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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