Tokaido Shinkansen Power Outage Caused by Damaged Overhead Power Lines – JR East

On June 6th, JR Tokai announced that the cause of the power outage that occurred on the Tokaido Shinkansen Shizuoka section, resulting in approximately a 3-hour service disruption, was damage to the power supply cable on the top of a train that had stopped within the section. The power outage occurred on the afternoon of the 6th on the up-line section between Kakegawa Station and Shizuoka Station in Shizuoka Prefecture, leading to a suspension of service for about 3 hours on the up-line between Shin-Osaka and Tokyo and the down-line between Tokyo and Nagoya. According to JR Tokai's investigation, the power outage was caused by a 'ground fault,' where electricity flowed to the ground due to damage to the power supply cable located on the top of the 12th and 13th cars of the up-line 'Nozomi 12' train that had stopped in the Shizuoka Prefecture section. The power supply cable, with a diameter of about 5 cm, plays the role of drawing electricity from the pantograph and delivering it to each car. During a vehicle inspection on July 4th, no particular abnormalities were found. The cause of the power supply cable damage is currently under investigation, and JR Tokai is conducting inspections on all of its trains to ensure that there are no issues with the cables.

In addition to the power outage caused by the power supply cable damage, JR Tokai also disclosed that a trolley wire cut incident had occurred on the Tokaido Shinkansen on June 21, 2017. At that time, a trolley wire that supplies electricity to the train was cut on the Kyoto-Shin-Osaka section, where operations had been suspended due to heavy rain, resulting in delays of 172 to 365 minutes for a total of 63 trains on both up and down lines, affecting 51,000 passengers. The cause of the incident was attributed to the train stopping in the 'air section' where two trolley wires run in parallel.

On that day, operations were suspended for 3.5 hours due to heavy rain. Although operations resumed, there were significant delays. Prior to the incident, a line of trains had been stopped on the down-line in front of Shin-Osaka Station. One of them, the 'Nozomi 241' train, experienced the trolley wire cut at 7:48 PM from the pantograph location of the 12th car. At that time, JR Tokai was unaware of the trolley wire cut. At 7:53 PM, when the 'Nozomi 241' train began to move, the severed trolley wire touched the roof of the same train, causing a ground fault and leading to a power outage. Holes were created in the side walls on both sides of the pantograph due to the ground fault current.

Subsequently, whether the trolley wire detached from the train body or the power supply was restored, the cause of the power outage remained unclear, and operations resumed. However, when the subsequent train, 'Nozomi 391,' arrived at the scene, the severed trolley wire touched the area around the pantograph (the one closer to Shin-Osaka) of the 5th car, causing another ground fault and a power outage. Similarly, holes were created in the side walls.

It took 5 hours for staff to investigate the cause at the scene and restore the trolley wire. The direct cause of the trolley wire cut was considered to be the flow of a large electric current between the pantograph and the wire, resulting in Joule heating (ジュール熱) and arc discharge (アーク放電).

These incidents, both the recent one and the past trolley wire cut incident, have raised concerns about safety in high-speed rail operations within Japan. JR Tokai needs to prioritize safety, thoroughly inspect the power supply cables and trolley wires of all trains, and strengthen its preparedness for potential operational issues.