Technologies offering a stable and efficient supply of electric energy are attracting greater attention as expectations grow for renewable energy that can replace nuclear power while also protecting the environment from global warming and other hazards. There is an increasing demand for space-saving, energy-saving and highly reliable electric distribution and supply systems for not only factories and production facilities, but also for office buildings and commercial facilities.
Fuji Electric is meeting these needs through extensive development and renewal activities based on cultivated technologies for our energy-saving system equipment, high-voltage equipment and compact devices optimized for electric distribution and supply systems and structure of various machines. As a result, we have established a reputation for releasing products in a timely manner that match the market needs of both Japan and countries around the world.
In this special issue, we will be introducing the latest electric distribution, switching and control technologies and devices that are contributing to secure and efficient power supply while also further advancing Fuji Electric's switching and breaking technologies.

Electric distribution, switching and control devices are indispensable components of electrical equipment and are expected to play a supporting role in the environmental and energy fields. Fuji Electric magnetic contactors have been fulfilling their part for 60 years, and the production has reached to 300 million units. Recently, our magnetic contactors have achieved a more compact size and higher performance, making them suitable for inverter and servo circuits and the control systems of new types of motors. Our control equipment meets the demands of strict safety requirements. As for low-voltage electric distribution devices and power monitoring equipment, we have developed DC high-voltage devices in correspondence to the needs of renewable energy. We have pursued life-cycle costs and ease-of-use in the production of our high-voltage electric distribution devices and have achieved specifications that provide our customers with added benefits when replacing their equipment.

A magnetic contactor is a control device that mainly starts and stops motors, and demand for them is increasing in the Chinese and Southeast Asian markets. Fuji Electric has expanded the economical magnetic contactor “FJ Series” product line intended for the markets and the compact-sized magnetic contactor “SK Series” product line ideal for inverters and servo amplifi ers. To the FJ Series, we have added products with 40 to 95A ratings and optimized the support sliding-portion design to ensure a small size and high reliability. For the SK Series, we have developed 18A and 22A products, which are higher ratings than the existing 6 to 12A, to successfully improve the limit performance of contact welding resistance for inrush current by 2.5 times that of the existing products.

Of operation switches used for various devices and machines, emergency stop pushbutton switches are very important ones intended for preventing disasters. In order to meet various customer demands for safety, Fuji Electric has released emergency stop pushbutton switches (φ22 and φ30) integrating the “Synchro Safe Contact,” which has the companyʼs proprietary structure. A separated contact block structure has been adopted to allow safe operation of the contact mechanism when the operation and contact parts are separated. In addition, to im-prove mechanical endurance and contact reliability, we have realized a contact part structure with excellent environmental endurance in the panel depth dimension of 47.5 mm.

6kV power systems in Japan, vacuum circuit breakers (VCBs) are widely used as the main circuit breakers. In particular, fixed-type VCBs are often used in CB-type cubicle high voltage power receiving facilities specified in JIS C 4620. These facilities are often used outdoors, and high performance under severe environmental conditions such as dust and high temperature/humidity is required. Fuji Electric has developed “MULTI.VCB” (fixed-type), which features improved environmental endurance and reduced life cycle costs realized by simplifying the mechanism and maintaining compatibility. We have also developed “Auto.V,” which combines this VCB with digital OCR and CT.

High-voltage distribution facilities have recently been increasingly demanded for applications including grid connection of solar power generation facilities and other distributed power sources, in addition to power supplies to buildings and factories. Fuji Electric has a track record of many deliveries of high-voltage air load break switches (LBSs), which is a major device of high-voltage distribution equipment. With the contactor integrating the functions of the existing two types of contactors, main circuit structure that does not require a fuse to be mov-able and the ensured arc extinguishing performance achieved by optimization of the arc extinguisher structure, a more compact and simpler structure than the conventional devices has been realized.

With photovoltaic power generation facilities for applications other than residential use, the voltage is being increased along with the increase in system capacity, and there is a demand for non-polarity breakers that are capable of safely interrupting currents in the opposite direction and handling high voltages. In order to realize such a breaker, Fuji Electric has improved the structure of the arc extinguishing chamber. We made two structural designs and then conducted a magnetic field analysis and an interrupting test for their verification. We have thereby achieved the improved structure that realizes stable interruption performance from small to large current. This has allowed us to realize the non-polarity of high-voltage direct current breakers while ensuring compatibility with the conventional devices by maintaining the same rated operational voltage, breaking capacity and dimensions.

Applications of Direct Current power distribution systems are expanding along with the expansion of renewable energy use, and this has created an urgent need to establish protection technology for their safe operation. Fuji Electric has verified and established short circuit and ground fault estimation technology as protection technology for direct current power distribution systems. We have built an equivalent circuit based on the impedance characteristics of a storage battery to estimate a short circuit fault in the vicinity of a storage battery. We have analyzed the ground fault current waveforms of grounded and ungrounded systems to estimate the ground fault. Moreover, based on the estimation technology, we have built our product line to make it easier for users to select the appropriate protection devices.

In the development process for distribution, switching and control equipment components, product evaluations encompassing many items are required to satisfy product specifications and meet market demands.
Fuji Electric builds product quality by implementing four kinds of evaluation: a screening evaluation on factors determining product performance, a reliability evaluation in view of a product use environment, an interface evaluation that considers handleability, and a charac-teristic evaluation based on product standards. With these evaluations, Fuji Electric makes our products meet their specifications to increase customer satisfaction while improving the efficiency of our overall development.

With distribution, switching and control equipment components, requirements for employed materials are becoming stricter year by year due to the tightening of environmental regulations such as the RoHS Directive and to address environmental issues including global warming.
Concerning metal materials, Fuji Electric has worked on eliminating Cd from contacts and realized it by achieving the wear resistance and temperature rise targets. For polymeric materials, we have successfully replaced thermosetting resin in insulating parts with thermoplas-tic resin and reduced waste in thermosetting resin.

With distribution, switching and control equipment components, finding a way to predict and control the behavior of the arc generated by contact switching is an important technological challenge. Fuji Electric has developed arc simulation technology that couples thermal fluid analysis with electromagnetic field analysis for further miniaturization of components, improvement of performance and accommodation of direct current devices. The arc simulation technology makes it possible to use structure of an actual device to visualize its behavior or arc for quantitative evaluation of gas flow and electromagnetic force.

The market environment of distribution, switching and control equipment components is rapidly changing due to globalization and widespread direct current power supply systems, and the marketʼs needs are becoming increasingly diversifi ed. In order to supply products with a guaranteed quality and delivery time that are better than before, it is necessary to construct a global supply chain system and develop new production technologies in manufacturing. As part of the construction of a global supply chain system, Fuji Electric is working to have local production for local consumption, establish an integrated system and adapt production lines to handle high-mix low-volume production. We are also developing new production technologies including parts supply technology, joining technology and robot utilization technology.