On the Earth-Current Disturbance at Haranomachi caused by the Leakage Current from the Electric Railway, Fukushima-Yonezawa
Yanagihara, K. & Osima, H.
Abstract
From April 1949，some strange but minor disturbanc of similar type have been recorded at nearly constant times on each electrogram at Haranomachi; we call it here“W-type" disturbance. (Fig.1，Fig. 4 and Fig.5) After some preliminary works those disturbances were supposed to be some artificial ones caused by the leakage current from the electric railway near Haranomachi，O-u Line from Fukushima to Yonezawa， or Fukushima Dentetsu Line(Pig.3)，and further examinations supported the estimation that the O-u Line affected predominantly the earth-currents at Haranomachi.
Then，in May 1952. quick-run recording of earth-current potentials at Haranomachi，observations of current supplied at Niwasaka, one of the transformer stations，and those of distance-time and current-time curves for each train were performed for several trains of usual service，including the express "Chokai". (Fig. 11) And thus it was confirmed that the “W-type" disturbances were
due to the leakage current from the electric railway， O-u Line， and that the first half of W-variation was appeared only when the train run from Fukushima to Sasakino，and the other half did from Sasakino to Niwasaka. Some detailed numerical discussions were done in S 4，5. If it is assumed that leakage coefficient of rails， α=0.153km-1，total current supplied， I = 1000 ampere， electric conductivity of the earth，σ=6X10-5 ohm-1 cm-1, the earth-current potential gradients at Haranomachi， E， for each position of train can be given as in Table 1， 2.
By this calculation，numerical values of the“W-type" disturbance can be deduced fairly well. (dotted line in Fig. 11) And furthermore，it can be justified that there are predominant effects when the train or locomotive only runs near Fukushima，while none when the train runs further away from Niwasaka.
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