1965: success in fabrication of silicon carbide varistors by R&D group of Panasonic company in Japan for protection against impulse voltages
November 1965: taking the responsibility of improvement of semiconductive varistors by Matsuoka
1967: success in obtaining zinc oxide varistors but with a low threshold voltage and one-directional electrical conduction
July 1967: damage of sintering furnace of one of the samples, occurrence of thermal runaway in it and increase of samples temperatures above the desired amount in test of overfired sample by Matsuoka
Symmetrical conduction with a higher threshold voltage in both positive and negative polarities in the overfired samples
1968: universal patent by Matsuoka’s team and production of metal oxide surge arresters
1972: joining of varistor-type semiconductors scientists to Matsuoka’s team and fabrication of industrial metal oxide varistors with voltage of 500V
1977: Addition of other metal oxides and obtaining high-voltage varistors
1980: achievement of this technology by Toshiba company, the largest manufacturer of surge arrester
1990: abandon of this business by the initial designers and manufacturers of surge arresters
1995: publication of one patent by Hubbell company and revolution of surge arrester
Technology variation from ceramic insulators to fiberglass bars coated by silicon coatings
Increase of surge arrester lifetime