The structure of electricity demand has been changing as the priority of technical innovation transfered from heavy industrial fields to high technological fields being represented by electronics. Consequently, the high quality power supply for buildings and equipment has become more important. This paper includes the following: (1) Power distribution (2) Non-utility generation (3) Stabilized power supply and high-frequency power source utilized inverter technology. Further, it introduces that, besides the above long-term viewpoints, Fuji Electric is a aiming at (1) Higher level circuit system, (2) Development of uninflammable equipment, (3) Introduction of co-generation system,(4) Application of high frequency with new power devices, and (5) Higher function using digital control.

Various requirements have been recently brought up concerning the power generating and distributing equipment for building services including public installations, to realize economical price level, smaller size, fireproof property, lower noise level, better quality of supply and proper mainteinability. Besides, power consumption for building service also has been increased. Thus several supervising systems for building services to save energy and labor are being adopted.
The paper outlines features and constructions of such electrical equipment to meet above requirements as 60 and 70kV-class C-GIS, gas-insulated transformers, 20 and 30kV-class switchgears, C-GIS, molded transformers, medium-voltage switchgears of short depth type, generator packages and so-called"building automation systems".

Uninterruptible power supply units UTP series have been developed to cope with the increase of computerized branches of banking facilities. A Diesel generator, UPS, and other necessary devices are packed in a soundproof package. It is possible to combine one of the CVCF outputs for terminal computers, 3, 5, 7.5, or 10kVA, with one of the outputs for auxiliary equipment, 5 or 7.5kVA. Moreover, they have such features as low noise(75 phone) during the Diesel-generator operation, easy installation with small size and light weight, etc.

With the progress of electronic equipment represented by computer, the quality of commercial electric power source has become more important. To supply electric power stably to such loads, UPS and AVR are employed. This paper describes the circuit configuration, features and standard specifications of the newest UPS and AVR by Fuji Electric, with an eye to explaining important points to get good coordination with computer load.

Recently, small size and low-cost computer application equipments has been advanced, and UPS is strongly demanded to be low-cost besides small size. Fuji Electric developed new type mini-UPS series with 1 to 3kVA output. Power MOS FET and custom-made LSI is used to the main circuit and to the control circuit, respectively. The circuit is simplified, and compactness and low cost are realized. This paper introduces their specifications, features, circuit configuration, structures and characteristics. By applying high-frequency technology and instanteneous voltage control method, the output voltage regulation less than 3% at 100% sudden load change and the output voltage distortion factor of 2.8% at rectified load are achieved.

The superior performance of SF₆ gas-insulated switchgears has led to their increasingly wide use over the last ten years. The increasingly widespread use such switchgears has contributed to reductions in the size of whole substation systems.
A number of C-CIS's, developed by Fuji Electric have been delivered to non-utility customers since 1983, and have operated satisfactorily at the customers' substation to receive and distribute power from utility systems.
This article describes Fuji's C-GIS's and their application to non-utility customers' high-voltage substation systems.

The House substation equipment for building services is extremely important one as a power source for such essential units provided in buildings as air-conditioners, lighting apparatus, computers, etc. the reliability of the equipment related to power supplying performance must be exceedingly high above all. It is important to attain higher overall reliability of the substation operation with higher reliability level of each component, including quality improvement of installation work at site. Introducing several recently delivered products, authors give a summary of system planning and consideration for the installation work to improve the overall reliability of the house substation operation.

The construction of so-called "intelligent buildings" and the remodeling of old buildings to make them "intelligent" is becoming more common, owing to the increased use of office-automation equipment and advanced information networks.
Attempts are being made to improve the productivity of the manufacturing process at factories through automation and energy-saving measures. The reliability and safety of power distribution systems and their components must be improved in order to allow such systems to properly fulfil their functions. Several such improvements are discussed in this paper.

The renovation of electrical equipment in existing buildings and the addition of supplemental equipment to existing distribution systems have increased recently, mainly because of the deterioration of older equipment, changes in building use and the increasing number of functions required by intelligent buildings. This paper introduces suggestions for planning such renovation additions, given the restrictions imposed by existing buildings, and brief descriptions of recent examples of the renovation of extra-high-voltage distribution systems.

The co-generation system (a system for supplying both electricity and heat) has been noticed recently and seem to come into wide use rapidly under the support of Ministry of International Trade and Industry. This paper introduces the basic plans of the application to general users, consisting of an outline of co-generation systems, system configuration, study of economical efficiency, parallel operation with purchased power, application of synchronous generators and induction generators, and so on.

Computers have beeen introduced in various ways as the information-oriented society rose to a higher level. Usually medium-sized computer systems have their own rooms and are provided with ancillary facilities to secure stable computer operation and safety. Ancillary facilities should satisfy the requirements for computer specifications and system importance. This paper describes an outline of planning for computer ancillary facilities such as air conditioning, power supply, disaster and crime prevention, lighting, flooring work and integrated management system, and some suggestions as well.

The present age is called the age of information and communication utilizing high-technology, and information transmission is performed with on-line real time systems, which must not be stopped in any circumstances. UPS applying CVCF inverter has been utilized for such very important systems. Recently, UPS has been applied to various uses such as motor load with large rush currents, process control with rich harmonic current components, broadcasting, and electric lighting. CVCF is also used foe the testing power source independently. This paper introduces various application examples of CVCF inverters.

Lead acid batteries and alkaline batteries are utilized for UPS. There is a recent technical trend toward maintenance-free construction. This paper explains the battery with catalizer plug and the seal battery of gas absorbing type at cathode, laying weight on their action, and as future trends describes an outline of application examples of new kind batteries and alkaline fuel cells to UPS.

New semiconductor power devices such as bipolar transistors and SIT(Static Induction Transistors) were applied to high-frequency power system, which have been made fit for practical use recently.
This paper introduces an outline of the power supply equipment of 50kHz-class output frequency including bipolar transistors for inductive load use and those of 100kHz-class output frequency including SIT for capacitive load use, and their circuits and characteristics as well.