Tomonori Iino

A study of the safety of the DC 400 V distribution system

Recently, higher voltage (here we assume about 400 V DC) direct current (HVDC) distribution systems have been recommended to reduce the power consumption of telecommunications buildings and datacenters. However, safety measures for these systems have not yet been established. There are many potential hazards with electricity, such as electric shocks, burns, and fires. Ventricular fibrillation caused by electric shocks is especially dangerous. Preventing electric shocks is important for any HVDC distribution system. We report the effect of “direct current” and “higher voltage”, characteristics of HVDC systems, on the human body via electric shocks.

Degradation of Output Characteristics of a Small Photovoltaic Module Due to Dirt Spots

This paper reports the output degradation characteristics of a small photovoltaic cell when a dirt spot adheres to the surface. The 11 W photovoltaic module GT434 was applied to various electric systems. The module consists of 34 cells, cut to 1/4 the silicon single crystal photovoltaic cell of a square with one side measuring 103 mm. The photovoltaic output power was found to be reduced by 50% when a 3% dirt area was applied to the small module. The decrease in output power was shown to improve when the shape of the photovoltaic cell was changed

Characteristics of 400 V dc plug and socket-outlet for DC distribution systems

This paper reports test results and reviews for the developed plug and socket-outlet applied to the 400 V dc power systems expected to improve energy efficiency in communication sites, data centers, commercial buildings, and smart energy systems. However, there are some safety issues to use 400 V dc power. The plug and socket-outlet has a unique mechanism based on combination of a permanent magnet and mechanical contacts in the limited small space. The mechanism should solve the problems such as both arc extinguishing and protection against electric shock known as critical DC power issue for a long time. The results of an investigation of inrush current also are reported, including current size, effects and testing methods, as one problem in the construction and operation of 400 V dc power distribution circuit.

Development of 400 Vdc plug and socket-outlet for DC distribution system

This paper reports test results and reviews for the developed plug and socket-outlet applied to the 400 Vdc power systems expected to improve energy efficiency in communication sites, data centers, commercial buildings, and smart energy systems. However, there are some safety issues to use 400 Vdc power. The plug and socket outlet has a unique mechanism based on combination of a permanent magnet and mechanical contacts in the limited small space. The mechanism should solve the problems such as both arc extinguishing and protection against electric shock known as critical DC power issue for a long time.

Small Photovoltaic Module with Rectangular Cells for Reducing Output Degradation Caused by Spot Dirt

This paper reports the output degradation reduction when spot dirt adheres to a small photovoltaic module with rectangular cells. A small photovoltaic module of 13 W was applied to various electric systems. The module consisted of single crystal silicon photovoltaic cells. The effect of the output degradation was studied by changing the aspect ratio of the photovoltaic cell. It was also studied the effect by changing the photovoltaic cell connection applied to the module. Changing the aspect ratio of the photovoltaic cell used for the photovoltaic module results in suppression of the output degradation by 80% or less with 3% of spot dirt on the module area

Shared Distribution Fuel Cells for Community Center and Many Houses

We have studied the characteristics of a shared distribution fuel cells system which is shared by a community center and many houses surrounding it. The system was confirmed to be effective. The utilization factor of the fuel cells was improved by about 20%, decreasing the generation cost of fuel cells and the environmental burden

Reducing Cost and Decreasing CO2 Emission Using a Shared-Distribution Fuel Cell System

We studied the characteristics of a shared-distribution fuel cell system that supplied a community center and several houses. The system was confirmed to be effective. Compared to costs estimated before the proposed system was installed, this is projected to become economically viable after 9 years with low CO2 from the first year