IEEE Electrification Magazine - September 2013 - 12

JR companies need to keep punctuality,
reliability, and availability at a high
level to guarantee effective operation.
To keep a mass transit system like the
Japanese system running, some
redundancy for fixed installations
is required.

Variety of Systems

The world's first
dedicated highspeed rail line-
the Shinkansen-
was built between
Tokyo and Osaka.

Japan is a country of islands and has
no land borders. However, in the early
20th century, several railway companies and electric power companies imported from both
Europe and the United States. The Japanese government
wanted to unite the systems but failed. Hence, JR run on
various systems:
 the frequencies 50 Hz (eastern Japan) and 60 Hz (western Japan)
 the gauges 1,435 mm (Shinkansen and some commuter lines) and 1,067 mm (conventional lines)
 three power types-ac 25 kV (Shinkansen), ac 20 kV
(conventional), and dc 1.5 kV (conventional).
In Tokyo Station, several types of power supply meet
each other. The Tokaido and Tohoku Shinkansen use
25 kV, 60 Hz, 1,435-mm gauge, and 60 and 50 Hz,
respectively. Commuter lines use dc 1.5 kV and
1,067-mm gauge. The Metro supplied by dc 600 V via
third rails running on 1,435-mm tracks should also be
mentioned.

History and statistics
DC Traction, History, and Today
Table 2 shows a brief history of Japanese electrification.
The electrification of the former Japanese National Railways (JNR) started with dc 600 V in 1904 and was

upgraded to 1.2 kV in 1914. Then, JNR
decided on dc 1.5-kV traction as
standard in 1925. In the early days, all
electrification-related devices needed to
be imported from Europe or the United
States and were very expensive. Therefore, JNR and Japanese electric industries began to manufacture devices in
Japan. Before World War II, JNR and
many private railway companies had
about 6,000 km of electrified lines. After
the war, JNR began to electrify all trunk
and commuter lines around big cities. Also, many cities
expanded metro rail lines in their area.
As of April 2013, JR commuter lines in Tokyo, Osaka,
and the Nagoya area and the trunk line from Tokyo to
Osaka and other lines use dc 1.5 kV on a total length of
6,363.7 km. Bigger private railways with approximately
2,600 km of dc 1.5-kV lines convey many commuters
from suburban areas to city centers, and ten cities
have a total combined metro line length of 857 km.
About 1,650 substations with about 2,700 rectifiers
support 49,000 electrical multiple unit (EMU) cars for
all JR.
Beginning in the 1970s, Japanese dc EMUs used
chopper control technology for dc traction motors,
enabling regenerative braking. After the 1980s,
asynchronous traction motors with voltage-fed inverter
technology were adopted. Now, more than 80% of
Japanese EMUs can use regenerative braking. New
materials such as aluminum and stainless steel help to
save weight in the bodies. After the Tohoku Earthquake off
the Pacific coast on 11 March 2011 and the resulting power
shortages, JR had to save more energy. Thus, several
railway companies installed energy-storage systems with
lithium-ion batteries, supercapacitors, or flywheels.

AC Traction

Figure 1. The departure of the first Shinkansen in 1964.

I E E E E l e c t r i f i c atio n Magaz ine / september 2013

In 1953, Sounosuke Nagasaki, the president of JNR, went to France to learn the
state of the art of ac traction from the
Société Nationale des Chemins de Fer
Français. After that, he decided to test
commercial frequency ac traction as a
more economical and powerful electrification scheme than dc. The first experimental ac feeding circuit was electrified
in 1954 on the Senzan line in the north
of Japan. The equipment such as rolling
stock and fixed installations were developed in Japan. JNR's conventional lines
use a narrower gauge (1,067 mm) and
smaller infrastructure gauges compared
with those of Europe, especially in tunnels. Most power lines used 20 kV in
those days. So, JNR adopted 20 kV.

Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2013