As international competition got serious, necessity for the efficient and safe operation of production equipment has more and more increased.
This paper describes preventive maintenance technology such as methods for production equipment diagnosis, maintenance, and improvement in performance and reliability, including the details of Fuji Electric's development. In addition, it refers to basic technology and maintenance systems required from a viewpoint of life cycle costs, the current trend of preventive maintenance technology.

To maintain a plant control system, an integrated maintenance system taking into account the system life cycle is indispensable. This paper introduced Fuji Electric's integrated maintenance system "COMET" and describes the remote maintenance and CE database systems as the core of this system as well as economical effects due to its introduction. Also it refers to a method of solving the problem of operations in maintenance work in general.

Not only a function of human communication but also various functions of supporting the operation and maintenance have been required by operation monitoring and supporting systems in industrial substations. This paper outlines an advanced operation monitoring and supporting system, their components such as multifunction digital relays, multifunction digital controllers and local monitors, and a monitoring and supporting system for emergency power generating equipment.

Oil-immersed transformers used for 20 to 30 years since the start of operation are increasing. To supply electric power stably, it is an important subject to carry out the degradation diagnosis of transformers, principal equipment in substations, to ensure reliability and predict the time of replacement. This paper introduces the concept of degradation by aging, the status of investigations, into methods for degradation diagnosis, and actual application examples of CO₂ + CO analysis with an automatic gas-in-oil (GIO) analyzer and measurement of furfural in oil.

Maintenance is essential for the stable operation of equipment, so equipment diagnosis is indispensable. Fuji Electric has developed new diagnostic cars for rotating electric machines and substation equipment. The superiority of the one for rotating machines is automatic measurement, recording, characteristics calculation and evaluation, which has doubled the former capacity. The one for substation equipment is equipped with various latest measuring instruments capable of diagnosing equipment such as transformers, switchgears and switchboards by one car. The system can automatically output diagnostic results of various measured data processed by a computer.

This paper introduces the thermal aging diagnosis of the insulating materials of rotating machines using a physicochemical technique. This diagnosis can examine coil end spacers, which were difficult by conventional electrical characteristics tests, and other reinforcing parts with a sample of very small amount. When the diagnostic data of materials is available, this diagnosis can be applied to any of DC machines and thermal power generators, and when combined with the conventional characteristics tests, it is effective in grasping the degradation of a whole insulation system.

Partial discharge measuring technique is used in the research and development of power equipment such as gas-insulated switchgears and transformers and the evaluation of insulation reliability on factory tests and field operation. Preventive maintenance technology in the field is required to detect a trouble indication at an initial stage. This paper describes the typical partial discharge measuring technique which Fuji Electric already applied to power equipment, new measuring technique under development for application in the field and for low-voltage devices which will be a future field.

Recent thermal power plants are subjected to severe operation because of increase in starts, stops, and load fluctuations, so equipment diagnosis and maintenance are essential to ensure stable operation. Fuji Electric constructed and began to operate maintenance supporting systems for turbines which prepare a report by collecting and analyzing the maintenance records of existing power plants and date obtained in inspection using a personal computer and gives diagnosis and maintenance. This paper introduces an outline of the system.

Considering the importance of existing overage thermal power plants and the fear of trouble occurrence due to deterioration, for users to use them still for 15 to 20 years, Fuji Electric actively put forward a proposal for measures to lengthen the span of life, combining long accumulated maintenance know-how and the latest technology.
This paper introduces Fuji Electric's measures for the extension of life, the method of approaching for execution, and concrete technologies applied to them.

Fuji Electric has developed new innovation technologies for overage turbine generators and put forward a plan for improving the reliability of equipment and extending their life. With these technologies, the existing turbine-generator foundation can be reused and time required for innovation work can be shortened.
This paper introduces part of the technologies.

Overage thermal power plants, which are compelled to be subjected to severe operation, are required to be more reliable. Focusing on the improvement of reliability, Fuji Electric is positively tackling the innovation of these overage equipment. This paper describes the recent requirements of electrical and control equipment and an outline of the contents of Fuji Electric's carefully thought out proposals meeting these requirements, citing examples of the proposals.

The history of Japan's hydroelectric equipment is long and there are still a large number of overage equipment. The renewal of these overage equipment is in progress, while changes in the environment around hydroelectric equipment and recent technical developments have diversified the requirements of a repair or renewal as well as technologies to meet them.
This paper introduces recent technical requirements in existing hydroelectric stations and characteristic examples of modernization technologies for overage equipment.

Aiming to reduce the construction period and labor of on-site work in overhauling hydroelectric stations, Fuji Electric tackles the development of on-site machining technology and automated testing technology for water turbines. This paper introduces the technology of machining water turbine discharge rings and the testing equipment "Challenger-H" that automates measurement and date processing in load rejection tests.

The replacement of the semi-automatic control panels with full automatic ones in the fuel handling system of the advanced thermal reactor "FUGEN" was carried out and resulted in good follow-up phenomena with the existing machinery and a noticeable effect of the renewal. The radioactive solid waste handling manipulator has both functions of putting waste in order in a bunker and discharging waste in another bunker, which is described in the paper. In the planning of dismantling work, the application of three-dimensional CAE, the establishment of a data base, and the development of software for dismantling work management are referred to.