The puffer type GCBs are now widely used in many power transmission lines to switch or to protect those lines from various electrical faults. This type GCB was developed at first as medium capacity GCB with a limited short circuit interrupting capacity. Engineers in Hitachi Ltd. had been continuing challenges to develop high capacity puffer type GCB by their own ability, as Namihei Odaira established the company with a philosophy to develop electrical apparatus by the Japanese ability. This paper describes the situation of Hitachi at the starting point and efforts to have made a success in developing the world first 2-cycle high capacity puffer type GCB without any available engineering data on SF6 and GCB.
This paper describes historical trends of electric power system simulation technology. The first paper concerning power system simulation study was published in 1916, sixteen years later after the year 1900 when a practical high voltage three-phase ac power transmission line was constructed and put into operation in USA. Historical trends of power system simulation technology can be divided into three stages from the viewpoint of epoch-making progress. The first stage is to simulate the power system behaviors by using a miniature power system circuit called as artificial transmission line. The second stage started from simulations of transient behaviors by the differential analyzer which enables to simulate transient behaviors by calculating mathematical representation model without using miniature machines and circuits. Many simulation tools were developed for calculating the transient and dynamic behaviors by mathematical models. The third stage is the digital simulation technology. This paper introduces the developed simulation technologies and describes the background and needs of the developed technology, furthermore observes on simulation technologies to be developed in the future from the viewpoint of historical trends of simulation technology.
This paper reviews historical trends of electric power system simulation technology focusing on the method of symmetrical coordinates and ac network analyzer. The method of symmetrical coordinates was proposed by C. L. Fortescue in 1918. The method of symmetrical coordinates was refined from the original usage and became very easy application form for ac network analyses by S. Bekku in Japan. The origin of ac network analyzer was invented in 1925. Ac network analyzer was improved greatly in its operation by applying the method of symmetrical coordinates particularly in analyses of power networks under unsymmetrical conditions. On the other hand, the method of symmetrical coordinates was improved by the idea of equivalent circuit which was born from application of the method to ac network analyzer. This paper describes historical interactive relationship in establishment of the method of symmetrical coordinates and ac network analyzer.
The power electronics apparatuses in the fields of transmission & distribution, industry and electric railway have made a very radical progress since 1960s, when the semiconductor power devices started to be applied practically. This paper presents the history of development in each field from the aspects of power device, main circuit and control method. Technical trends common to those fields are the concentration of main circuit to the voltage source inverter with MOS gate power devices, and high performance digital control circuit with micro processors. Tasks for the growth are the R&Ds aimed to overcome the demerits of power electronics, for examples, voltage surge, EMI and so on, to develop power electronics apparatuses applied to various power supply systems, and to harmonize stress with timing in R&D process.
Surge arresters have contributed to supply electric power suppressing lightning surge on transmission lines in case of the occurrence of lightning phenomena.Surge arresters using zinc oxide (ZnO) elements are suitable for insulation coordination, and are enable to reduce LIWV (Lightning Impulse Withstand Voltage) and construction cost of power systems. This paper describes transitions of developments, applications and standard of surge arresters for power systems.
In 1953, the study committee on restriking voltage was organized by Electric Technology Research Association of Japan. The result of researches made by the committee was reported in 1956 CIGRE. The report pointed out the case of severe restriking voltage which is realized at some occasion of transmission line fault. That phenomenon was not so seriously noticed by the contemporary engineering circle, but a few years later, it was keenly discussed and recognized as “kilometric fault" or “short line fault" (SLF). Authors carried out intensive studies on the arc dynamics around current zero and had realized demerit of air blast circuit breakers and excellence of SF6 gas circuit breakers in case of SLF. This conclusion led to the development of original gas circuit breakers, and finally to the best and most reliable puffer type GCB, at that time. That was a big step to the age of SF6.
The history of traction drive elevators in Japan is described. The electrical technologies such as the microprocessor car control and the VVVF motor control made remarkable progress leading to higher reliability and energy savings. Then, the various machine-room-less elevators have been developed and the space saving technology, such as the shuttle and the double-deck elevators become important, too. The elevators used for evacuation in case of emergencies are also discussed.
This paper studies the history of high voltage circuit breaker engineering. Methods of analysis are (1) to collect facts in regard to its development, (2) to review the history in order to find essential factors and (3) to identify its pros and cons from engineering point of view. The amount of electric power consumption has increased and gradually the circuit breaker concept was developed. At first the oil circuit breakers were developed in Europe and the air circuit breaker and vacuum circuit breaker were developed. Finally the SF6gas circuit breakers are developed together with the gas insulated switchgear and what is next? The future research and development policy is also discussed.
The report provides a relevant explanation about the advance of the television technology, especially about the systems and the receivers, from the beginning of the television development. (1) From the beginning of TV development to World War II. (2) Resumption of TV development by the end of war. (3) Monochrome TV to color TV. (4) Television technology in New Media, Multimedia and IT era.
The history of electrical rotating machines such as generators and motors in Japan is around one hundred years. At early stage, all machines were imported from foreign countries, but now domestic industries introduce new concept of machines and are leading these kinds of technology. Reviewing of history and development and foresight seems meaningful for further development.
This paper presents historical progress on technology evolution of the electric and electronic household appliances using the inverter, especially for Induction-Heating applications, which have been put in practical use as the desk-top cooker for the first time at home in 1974 until being applied to the rice cooker and the multi-burner cooking heater. It also describes the future innovative evolution of the power semiconductor switching devices and the inverter circuit topologies supporting its progressive developments. Looking back its progress, the future trends on consumer power electronics is discussed on the practical problem in the future.
Switching theory was developed as a theory for relay circuits in early days. In September 1935 Akira Nakashima of NEC delivered his invited speech on synthesis theory of relay networks including de Morgan’s theorem at the technical meeting of the Telegraph and Telephone Society in Tokyo. Since 1934 he had published his ideas in a series of papers “Theory and practice of relay circuits." Akira Nakashima and Masao Hanzawa formulated the design method for switching networks by using algebra in 1936. This is the first paper on switching theory that was applied to the analysis of digital circuits. It was in 1938 that the paper on switching theory was published by Claude E. Shannon. Following Nakashima’s research Kan-ichi Ohashi, Mochinori Goto and Yasuo Komamiya of Electrotechnical Laboratory (ETL) extended the theory to apply to sequential circuits.
This paper has been developed on the base of a presentation and its discussion made in the HEE (Technical Committee on History of Electrical Engineering) study meeting, in which authors showed their experiences in the construction work of pumped storage power stations in Japan. History study on these experiences will provide us with several important suggestions to understand the essence of engineering so that we will find the key to the successful technological innovation. This paper reviews the history and experiences of pumped storage power stations construction in Japan to analyze the key to the success in applying the innovative technology to practical engineering and to commercial plant construction, taking some actual cases into account. One of the most important suggestions is that “common sense” will sometimes be an obstacle to the successful innovation.
Propagation characteristics of seven lowest modes of leaky Lamb waves in a layered substrate composedof a piezoelectric ceramic plate and an acrylic plate, under the condition of a liquid-solid boundaryat the acrylic plate side, are described in the relationshipwith operation performances of an interdigital transducer (IDT) for underwater ultrasound. The IDT operates effectively for radiating or detecting via a mode conversionfrom the leaky Lamb wave to a longitudinal wave in a liquid. The incorporation of a layered substrate is useful for multiple-modes operations with higher transducer efficiencies, while retaining sufficient mechanical strength. It is noticeable that the cross points of the velocity curves of the leaky Lamb wave modes and the longitudinal wave modes in two kinds of thin plates for the layered substrate are unique for the transducer operations. The transducer operations are examined in the construction of a liquid delay line. The transducers designed for operating on the cross points of three modes are well explained in comparisonbetween the calculated and experimental results.
Non-thermal plasma produced by pulsed power discharge in atmospheric pressure gases has been studied for high-efficiency treatment of exhaust gases. In this paper, a short duration of 40 ns pulsed power has been applied to a mixture of nitrogen, oxygen, and water vapor, simulating flue gases to remove nitric oxide (NO). The effects of NO initial concentration and the pulsed repetition rate on the percentage of NO removal are reported. The results showed that all NO could be removed completely at different pulse repetition rates for different NO initial concentrations. The NOX removal ratio has a peak for a certain input energy. The removal of NO increased with increasing input energy density to NO (J/NO) at different NO initial concentrations.
This paper has discussed area effect on breakdown field strength in vacuum gaps under non-uniform field. To identify whether the common area effect can be found between uniform and non-uniform field gaps or not, 50 % breakdown field strength (E50) vs. electrode area more than 90 % of maximum fields strength on cathode (S90) was compared among four kinds of plate-plate gaps, three kinds of ring-plate gaps, and two kinds of sphere-plate gaps. As a result, E50 vs. S90 for plate-plate gaps shows different characteristics from the other kinds of gap arrangements when radial curvature of edge is large and gap length is short. We discussed the reason and how to conduct the insulation design for actual high voltage conductors, consist of some curved surfaces and plane surfaces.
For the purpose of improving the speed of the charging process of electrophotography, a new electrode system was investigated. The system consists of a blade electrode and a metal drum coated with a polymer film. The sharp edge of the blade electrode was retained perpendicularly for the drum surface by opening 2 to 6 mm gap. In order to prevent spark discharge, an 8 MΩ resistor was inserted between the blade and a dc high voltage source, and a glow-like discharge was observed in the space between the blade edge and the surface of the polymer film. As the discharge current obtained by the present electrode system was much higher than that obtained by a single wire corona charger, the charging speed attained by the present system was 7.2 times as fast as the case of the corona charging system.