After the Tohoku-Pacific Ocean earthquake, all Japanese railway operating companies had to tackle the problem of energy saving, since Japan lost a major part of its electric power resources. It followed that RTRI R&D on power supply technologies should adopt a similar focus. In addition, in the first half of this 21st century Japan is being confronted with falling birthrates, an aging society, and a shrinking population, causing a rapid decrease in the labor population. Given these circumstances, maintenance-free technology is another priority for RTRI. This paper describes recent topics related to power supply technologies.

This paper outlines problems relating to the joint application of railway operation information and recent research and development into information networks, train operation control and telecommunication systems. This paper presents the basic concept underlying a network platform for railway operation and its benefits for train operation control, maintenance of facilities, etc. It also describes how the network platform will enable the integration of various types of data from relevant fields, and increase efficiency of maintenance thereby creating new value drawn from big data analysis or computer simulation. Finally, the paper introduces recent research into precise and adaptable train operation control methods and applications using millimeter wave radio.

RTRI is advancing the fundamental research and development concerning superconducting maglev. The topics of this issue are characteristics of maglev vehicle dynamics, experimental production and evaluation of REBCO high-temperature superconducting coils. RTRI is also promoting the applied research based on maglev technology to the conventional railway system. The topics of this issue are the LIM-type eddy-current rail brakes and the flywheel energy storage system.

This paper proposes an electric contact model considering film resistance, such as an oxide layer, and describes a method for analyzing electric potential distribution and temperature distribution around a contact spot. As a result of the analysis, several laws governing the relationship between electric potential and temperature have been found, and a formula to calculate rising temperature was established using a factor calculated from contact resistance and film resistance. Finally, this paper proposes a map quantitatively showing transition conditions between wear modes.

Concrete catenary poles for electric railways are load-supporting members which support overhead contact lines and their fittings, etc., and their required mechanical strength is determined in consideration of the load which in turn depends on in-service conditions. To determine during maintenance whether a pole needs to be replaced due to deterioration it is important to be able to estimate its retained strength. Concrete catenary poles have been used on the railways on a wide scale for over 50 years. Therefore, there is a desire to determine criteria and standards that can be used to plan their replacement according to level of deterioration. This paper clarifies the main deterioration processes affecting concrete poles based on the results of field surveys on commercial lines, and bending and material tests on disused poles. This paper also proposes a method to determine whether a pole needs to be replaced or not.

In order to prevent damage and to extend the lifespan of equipment in railway power systems, it is necessary to detect early on any deterioration and to assess the residual lifespan of feeder transformers. As such a database containing information about the three main conditions affecting feeder transformers was constructed. First, load characteristics were researched to evaluate thermal deterioration. Second, analytical data of dissolved gas-in-oil was examined to evaluate damage from partial electric discharge. Third, the amount of furfural was investigated to evaluate the deterioration characteristics of insulating paper for feeder transformers. Based on the results of these investigations a lifespan estimation method for feeder transformers was developed. The validity of the estimation method was verified comparing experimental values with estimated values.

Wireless sensor networks have been used over recent years to monitor the condition of railway facilities. This paper focuses on wireless sensor networks designed to monitor the condition of train vehicles. To collect measurement data from sensors installed on each vehicle a network needs to be created between vehicles so that data in the sensors can be transmitted to the collection device via an appropriate route. However, coupling or decoupling raises the issue of how to modify networks when train composition is changed. As such, this paper proposes a two-tiered network composed of a single vehicle network and a multiple vehicle network, and describes the development of a method for creating multiple vehicle networks. This paper reports test results on a prototype system and results from a simulation using the proposed method.

Railway signalling systems have been damaged by lightning. Therefore, effective and economical lightning protection measures are necessary for railway signalling systems. To analyze lightning risk and study countermeasures against lightning damage, the authors therefore observed lightning overvoltage in electrified railway signal cables, electrical power lines and rails. Based on the result of these observations, the correlation between lightning overvoltage and lightning conditions was clarified, a methodology for estimating the probability of lightning hazards occurring was proposed, and it was found that according to statistics, there was no significant variation in overvoltage observed between electrified and non-electrified sections of railway.

Systems such as Automatic Train Protection and moving block sections help prevent trains colliding, however collisions with unexpected obstacles in front of a train can only be avoided if seen by the driver. In an effort to reduce the possibility of this type of collision and to improve passenger safety, an obstacle detection method has been proposed using a monocular camera and image processing. The proposed method can detect obstacles by comparing live images from the camera with images obtained by other trains operating earlier along the same route. The difference between the two sets of images are defined as obstacles. The performance of the method was verified by conducting experiments using rolling stock and imitation obstacles.

Flywheel energy storage systems (FESS) can moderate fluctuations in output from renewable energy such as solar photovoltaic power or wind power generation systems. A FESS was developed as a joint project involving five enterprises with financial support from the New Energy and Industrial Technology Development Organization (NEDO). The key technology used in FESS is the high temperature superconducting magnetic bearing (SMB). It consists of high temperature superconducting coils used for its stator and high temperature superconducting bulks used for its rotor. A FESS prototype was installed in the power plant, and its charge/discharge of solar photovoltaic power was monitored. Results from tests using a SMB subjected to a levitation time of 3,000 hours, 120 current value increase and decrease cycles and 24 heat cycles verified the reliability of the SMB.

To apply LIM-type eddy-current rail brakes to high-speed trains, it is necessary to miniaturize and reduce the weight of their armature mounted on bogies. This paper therefore considers reducing the volume of the iron core, taking into account the need to maintain braking performance at high speed, which has a great effect on braking distance. Electromagnetic field analysis was then used to verify the braking performance of the miniaturized armature by comparing it with armatures developed to perform well at low speed.

REBCO (Rare-Earth Barium Copper Oxide) is a high temperature superconducting material and allows on-board superconducting magnets on maglev trains to operate at higher temperatures. Because of the high operating temperature, the magnet can be cooled without liquid helium, reducing the magnet's energy consumption by nearly half. The basic technologies for making the magnet using REBCO coated conductors are still under development. A real-scale REBCO coil for application to maglev trains was therefore built. When excited at 35 K the real-scale coil demonstrated it had a magnetomotive force of 700 kA, which is the same as existing on-board magnets. This paper describes the manufacturing process of the coil and gives details of the excitation test.