No. 1090
	Present State and Trend of Technologies for Improving Non-Flammability and Less-Flammability of Power Transformers
	Investigating R&D Committee on Technologies for Improving Non-Flammability and Less-Flammability of Power Transformers
	The Investigation R&D Committee on Non-flammable and Less-flammable Transformers was constituted in 1990 and the investigation result was reported on mold transformers and gas-insulated transformers. Since then, the technology on non-flammable and less-flammable transformers shows some movements such as the developments of less-flammable liquid-filled transformers and the regulation of SF6 gas emission. In this context, the Investigation R&D Committee on Technologies for Improving Non-Flammability and Less-Flammability of Power Transformers was constituted on June 2004 and has been at research activities for two years. This report deals with the research results of the committee; the present state of operation and improving technologies of mold transformers, gas-insulated transformers and less-flammable liquid-filled transformers. Mold transformers are main products in indoor distribution transformers under 33kV and new technologies such as outdoor-use, recycling and loss reduction have been under development. In the near future, less-flammable liquid-filled transformers, using silicone fluids or vegetable oils, are estimated to be applied largely to power transformers in the standpoint of environmentally friendliness. On the other hand, in recent years, high-voltage large-capacity gas-cooled gas-insulated transformers have been developed and their applications to underground substations, which require high reliability for non-flammability, are expected to be increased.
	©2007. The Institute of Electrical Engineers of Japan